sample of search strategy for literature review

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How to write a search strategy for your systematic review

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Practical tips to write a search strategy for your systematic review

With a great review question and a clear set of eligibility criteria already mapped out, it’s now time to plan the search strategy. The medical literature is vast. Your team plans a thorough and methodical search, but you also know that resources and interest in the project are finite. At this stage it might feel like you have a mountain to climb.

The bottom line? You will have to sift through some irrelevant search results to find the studies that you need for your review. Capturing a proportion of irrelevant records in your search is necessary to ensure that it identifies as many relevant records as possible. This is the trade-off of precision versus sensitivity and, because systematic reviews aim to be as comprehensive as possible, it is best to favour sensitivity – more is more.

By now, the size of this task might be sounding alarm bells. The good news is that a range of techniques and web-based tools can help to make searching more efficient and save you time. We’ll look at some of them as we walk through the four main steps of searching for studies:

• Decide where to search
• Write and refine the search
• Run and record the search
• Manage the search results

Searching is a specialist discipline and the information given here is not intended to replace the advice of a skilled professional. Before we look at each of the steps in turn, the most important systematic reviewer pro-tip for searching is:

 Pro Tip – Talk to your librarian and do it early!

1. decide where to search .

It’s important to come up with a comprehensive list of sources to search so that you don’t miss anything potentially relevant. In clinical medicine, your first stop will likely be the databases MEDLINE , Embase , and CENTRAL . Depending on the subject of the review, it might also be appropriate to run the search in databases that cover specific geographical regions or specialist areas, such as traditional Chinese medicine.

In addition to these databases, you’ll also search for grey literature (essentially, research that was not published in journals). That’s because your search of bibliographic databases will not find relevant information if it is part of, for example:

• a trials register
• a study that is ongoing
• a thesis or dissertation
• a conference abstract.

Over-reliance on published data introduces bias in favour of positive results. Studies with positive results are more likely to be submitted to journals, published in journals, and therefore indexed in databases. This is publication bias and systematic reviews seek to minimise its effects by searching for grey literature.

2. Write and refine the search 

Search terms are derived from key concepts in the review question and from the inclusion and exclusion criteria that are specified in the protocol or research plan.

Keywords will be searched for in the title or abstract of the records in the database. They are often truncated (for example, a search for therap* to find therapy, therapies, therapist). They might also use wildcards to allow for spelling variants and plurals (for example, wom#n to find woman and women). The symbols used to perform truncation and wildcard searches vary by database.

Index terms  

Using index terms such as MeSH and Emtree in a search can improve its performance. Indexers with subject area expertise work through databases and tag each record with subject terms from a prespecified controlled vocabulary.

This indexing can save review teams a lot of time that would otherwise be spent sifting through irrelevant records. Using index terms in your search, for example, can help you find the records that are actually about the topic of interest (tagged with the index term) but ignore those that contain only a brief mention of it (not tagged with the index term).

Indexers assign terms based on a careful read of each study, rather than whether or not the study contains certain words. So the index terms enable the retrieval of relevant records that cannot be captured by a simple search for the keyword or phrase.

Use a combination

Relying solely on index terms is not advisable. Doing so could miss a relevant record that for some reason (indexer’s judgment, time lag between a record being listed in a database and being indexed) has not been tagged with an index term that would enable you to retrieve it. Good search strategies include both index terms and keywords.

Let’s see how this works in a real review! Figure 2 shows the search strategy for the review ‘Wheat flour fortification with iron and other micronutrients for reducing anaemia and improving iron status in populations’. This strategy combines index terms and keywords using the Boolean operators AND, OR, and NOT. OR is used first to reach as many records as possible before AND and NOT are used to narrow them down.

• Lines 1 and 2: contain MeSH terms (denoted by the initial capitals and the slash at the end).
• Line 3: contains truncated keywords (‘tw’ in this context is an instruction to search the title and abstract fields of the record).
• Line 4: combines the three previous lines using Boolean OR to broaden the search.
• Line 11: combines previous lines using Boolean AND to narrow the search.
• Lines 12 and 13: further narrow the search using Boolean NOT to exclude records of studies with no human subjects.

Writing a search strategy is an iterative process. A good plan is  to try out a new strategy and check that it has picked up the key studies that you would expect it to find based on your existing knowledge of the topic area. If it hasn’t, you can explore the reasons for this, revise the strategy, check it for errors, and try it again!

3. Run and record the search

Because of the different ways that individual databases are structured and indexed, a separate search strategy is needed for each database. This adds complexity to the search process, and it is important to keep a careful record of each search strategy as you run it. Search strategies can often be saved in the databases themselves, but it is a good idea to keep an offline copy as a back-up; Covidence allows you to store your search strategies online in your review settings.

The reporting of the search will be included in the methods section of your review and should follow the PRISMA guidelines. You can download a flow diagram from PRISMA’s website to help you log the number of records retrieved from the search and the subsequent decisions about the inclusion or exclusion of studies. The PRISMA-S extension provides guidance on reporting literature searches.

It is very important that search strategies are reproduced in their entirety (preferably using copy and paste to avoid typos) as part of the published review so that they can be studied and replicated by other researchers. Search strategies are often made available as an appendix because they are long and might otherwise interrupt the flow of the text in the methods section.

4. Manage the search results 

Once the search is done and you have recorded the process in enough detail to write up a thorough description in the methods section, you will move on to screening the results. This is an exciting stage in any review because it’s the first glimpse of what the search strategies have found. A large volume of results may be daunting but your search is very likely to have captured some irrelevant studies because of its high sensitivity, as we have already seen. Fortunately, it will be possible to exclude many of these irrelevant studies at the screening stage on the basis of the title and abstract alone 😅.

Search results from multiple databases can be collated in a single spreadsheet for screening. To benefit from process efficiencies, time-saving and easy collaboration with your team, you can import search results into a specialist tool such as Covidence. A key benefit of Covidence is that you can track decisions made about the inclusion or exclusion of studies in a simple workflow and resolve conflicting decisions quickly and transparently. Covidence currently supports three formats for file imports of search results:

• EndNote XML
• PubMed text format
• RIS text format

If you’d like to try this feature of Covidence but don’t have any data yet, you can download some ready-made sample data .

And you’re done!

There is a lot to think about when planning a search strategy. With practice, expert help, and the right tools your team can complete the search process with confidence.

This blog post is part of the Covidence series on how to write a systematic review.

Sign up for a free trial of Covidence today!

[1] Witt  KG, Hetrick  SE, Rajaram  G, Hazell  P, Taylor Salisbury  TL, Townsend  E, Hawton  K. Pharmacological interventions for self‐harm in adults . Cochrane Database of Systematic Reviews 2020, Issue 12. Art. No.: CD013669. DOI: 10.1002/14651858.CD013669.pub2. Accessed 02 February 2021

Laura Mellor. Portsmouth, UK

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Literature Reviews: systematic searching at various levels

• for assignments
• for dissertations / theses
• Search strategy and searching
• Boolean Operators

Search strategy template

• Screening & critiquing
• Citation Searching
• Google Scholar (with Lean Library)
• Resources for literature reviews
• Adding a referencing style to EndNote
• Exporting from different databases
• PRISMA Flow Diagram
• Grey Literature

You can map out your search strategy in whatever way works for you.

Some people like lists and so plan their search strategy out in a grid-box or table format. Some people are more visual and like to draw their strategy out using a mind-map approach (either on paper or using mind-mapping software). Some people use sticky notes or Trello or a spreadsheet.

If it works for you then as long as it enables you to search systematically and thoroughly there's no need to change the way you work. 

If your search strategies are not very developed, the method you use doesn't lead to a good search, then consider using one of the other methods to see if changing your approach helps.

• Search Strategy Document
• << Previous: Boolean Operators
• Next: Screening & critiquing >>
• Last Updated: Apr 12, 2024 11:57 AM
• URL: https://libguides.derby.ac.uk/literature-reviews

• University of Wisconsin–Madison
• University of Wisconsin-Madison
• Research Guides
• Evidence Synthesis, Systematic Review Services
• Write a Search Strategy

Evidence Synthesis, Systematic Review Services : Write a Search Strategy

• Literature Review Types, Taxonomies
• Develop a Protocol
• Develop Your Research Question
• Select Databases
• Select Gray Literature Sources
• Manage Your Search Process
• Register Your Protocol
• Citation Management
• Article Screening
• Risk of Bias Assessment
• Synthesize, Map, or Describe the Results
• Find Guidance by Discipline
• Manage Your Research Data
• Browse Evidence Portals by Discipline
• Automate the Process, Tools & Technologies
• Additional Resources

Searching Strategies, Search Syntax

While constructing a precise and productive search for the literature will take time and testing (or scoping), here are some useful tips on the mechanics for constructing search expressions that can be interpreted by database search engines. Search terms (keywords), operators, wildcards, and more!

• Be sure to visit the database "Help" files to learn about the special features, operators and wildcard characters that a database may uniquely use. 

See also sections 3 and 4 from the  CEE Guidelines for Authors.  ( Guidelines and Standards for Environmental Synthesis in Environmental Management , Version 5.1, 2022) Section 3:  Planning the conduct of an Evidence Synthesis Section 4:  Conducting a Search

A few fundamentals and tips:

Make a list of your search terms (keywords) and the alternative, like or similar concepts. You may find it helpful to consult a thesaurus (for example, see  NAL's Thesaurus and Glossary )

• As you run a search, review "subject headings" or "descriptors" to identify essential vocabulary.

Use  AND  to combine search terms; retrieve records with those terms, in any order:  friends AND communication

Use  OR  to combine similar search terms or synonyms:  friends OR peers

Use  quotation marks  ( " ") to search a required phrase:  "interpersonal communication"

• Note: In many instances, the adjacency of your search terms may be sufficient to retrieve a phrase. Unless specific phrasing is necessary for meaning (or to assist if retrieving too many erroneous results), enclosing your search phrases within quotation marks may be too limiting.

Use an  asterisk  ( * ) to retrieve singular and plural forms or suffixes for search terms: friend* = friend, friend s , friend ly  or friend ship

• Consult the Help files provided within the database to determine the correct symbol used for this function.

Apply field limits or filters to your results, if necessary (by date, document type, or other). 

Using the examples, above, and putting it all together as a simple search expression, you would have: (friend* OR peer*) AND "interpersonal communication"

Tools for Translating Your Search Syntax

• Database Syntax Guide (PDF), Cochrane Effective Practice and Organisation of Care Chart of commonly used syntax (operators, wildcard characters, field codes) and their behavior across several database products.
• Medline Transpose (project) Translate a search expression between Ovid MEDLINE and PubMed.
• Polyglot Search, SR-Accelerator Tool for translating search syntax across several database products.

Why Perform an Exploratory Search

In preparing for your review, you will begin with an exploratory or preliminary search of the literature. 

This search will help you:

• Identify existing reviews (so as not to duplicate work),
• Assess the quantity and quality of relevant, primary research studies (so as to be sufficiently abundant and productive for your work), and
• Identify key (benchmark) articles/publications with which to inform your subsequent searching.

Hedges, Search Filters

• ISSG Search Filter Resource (InterTASC Information Specialists' Sub-Group) Collaborative venture to identify, assess and test search filters designed to retrieve research by study design or focus.
• searchRxiv Resource created to support researchers by reporting, storing and sharing their searches to review and re-use.

How to Work with Sensitive Search Terms

• Addressing antiquated, non-standard, exclusionary, and potentially offensive terms in evidence syntheses and systematic searches Suggested wording provided is intended to be a template only, and should be adapted as appropriate for a given topic or project.
• AGROVOC, Multilingual Thesaurus, FAO
• CABI/CAB Thesaurus Stand-alone edition. Thesaurus can also be accessed from within the CAB Abstracts database.
• NAL Thesaurus (National Agricultural Library)
• << Previous: Select Gray Literature Sources
• Next: Manage Your Search Process >>
• Last Updated: May 30, 2024 2:53 PM
• URL: https://researchguides.library.wisc.edu/literature_review

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Writing a Literature Review

• Getting Started
• Defining the Scope
• Finding the Literature

Getting your search right

Keyword searches, widening your search: truncation and wildcards, combining your terms: search operators, being more specific: phrase and proximity searching, subject headings, combining keyword and subject heading searches, using methodological search filters.

• Managing Your Research
• Writing the Review
• Systematic Reviews and Other Review Types
• Useful Books
• Useful Videos
• Useful Links
• Commonly Used Terms

Test your strategy!

• Search the database for each of the test records and make a note of the unique record number for each one - in Medline this is in the UI field.
• Run your search strategy.
• Run a search for all the record numbers for your test set using 'OR' in between each one.
• Lastly combine the result of your search strategy with the test set using 'OR'.
• If the number of records retrieved stays the same then the strategy has identified all the records. If it doesn't, combine the result of your search strategy with the test set, this time using 'NOT'. This will identify the records in your test set which are not being retrieved. Work out why these weren't retrieved and adjust your search strategy accordingly.

Think about...

• abbreviations
• related terms
• UK/US spellings
• singular/plural forms of words
• thesaurus terms (where available)

Your search is likely to be complex and involve multiple steps to do with different subjects, what are often called "strands" or "strings" in the search. Look at the appendices of existing reviews for an idea of what's involved in creating a comprehensive search.

Most people should start by finding all the articles on Topic A, then moving on to Topic B, then Topic C (and so on), then combining those strands together using AND (see Combining your terms: search operators below). This will then give you results that mention all those topics.

You will then need to adapt (or "translate") your strategy for each database depending on the searching options available on each one. A core of terms is used across multiple databases - this is the "systematic" part - BUT with additions and subtractions as necessary. While the words in the title and abstract might remain the same, it's highly likely the thesaurus terms (if they exist) will be different across the databases. You may need to leave out some strings completely; for example, let's say you are doing a study that needs to find Randomised Controlled Trials (RCTs) on a particular disease and its treatment. You will be looking in multiple databases for words to do with the condition, and also words that are used for RCTs. But when you are looking in databases that are composed entirely of RCTs (trials registers), the part of a search looking for RCTs doesn’t need to be included as it's redundant.

The techniques described below will help ensure you cover everything. Contact your Subject Librarian if you would like guidance on constructing your search.

This video from the University of Reading gives a good overview of literature searching tips and tricks:

Jump to 01:45 for truncation and 05:46 for wildcards.

• Contact your Subject Librarian
• How to translate searches between certain databases A fantastic crib sheet from Karolinska Institutet University Library, showing how to translate searches between Medline (Ovid), PsycInfo (Ovid), Embase (Elsevier), Web of Science, Cinahl (Ebsco), Cochrane (Wiley), and PubMed.

Most searches have two elements - the "keywords" part and the "subject headings" part - for each topic. When you are initially constructing your search and trialling it in a database, you are likely to just add your keywords, click Search, and see how many that retrieves. But after that, for any type of comprehensive search, you should look at limiting your keywords to looking in specific search fields .

A field in this context is where the database only looks at one aspect of the information about the article. Common examples are the Author, Title, Abstract, and Journal Name. More esoteric ones could be fields like the CAS Registry Entry or Corporate Author.

In complex reviews like systematic, scoping and rapid reviews, the accepted wisdom is to limit these "keyword" searches to the Title and Abstract fields, plus (if available, and the search is looking to be comprehensive) any available "Author Keyword" or "Contributed Indexing" fields. It is vital that the keywords you use in these fields are identical - you are using the same words in the Title, Abstract and any related fields - and that you combine them using OR (see Combining your terms: search operators below)

Using keyword searching limited to the Title/Abstract/Keywords fields should reduce the number of results which are retrieved in error or are only on the periphery of your subject. If you do this, please be aware that you will need to ensure that you have definitely also included all relevant subject headings in your search strategy (in databases that use controlled vocabulary) otherwise you risk missing out on useful results. It *is* quite possible that there will be no relevant subject headings in a particular search.

Although some databases will automatically search for variant spellings, mostly they will just search for the exact letters you type in. Use wildcard and truncation symbols to take control of your search and include variations to widen your search and ensure you don't miss something relevant.

A truncation symbol (*) retrieves any number of letters  - useful to find different word endings based on the root of a word: africa*  will find africa, african, africans, africaans agricultur*  will find agriculture, agricultural, agriculturalist

A wildcard symbol (?) replaces a single letter . It's useful for retrieving alternate spelling spellings (i.e. British vs American English) and simple plurals: wom?n  will find woman or women behavio?r  will find behaviour or behavior

Hint: Not all databases use the * and ? symbols - some may use different ones (! instead of *, for example), or not have the feature at all, so check the online help section of the database before you start.

• Introduction

Search operators (also called Boolean operators) allow you to include multiple words and concepts in your searches. This means you can search for all of your terms at once rather than carrying out multiple searches for each concept.

There are three main operators:

• OR - for combining alternative words for your concepts and widening your results e.g. women OR gender
• AND - for combining your concepts giving more specific results e.g. women AND Africa
• NOT  - to exclude specific terms from your search - use this with caution as you might exclude relevant results accidentally!

women OR female

Using OR will bring you back records containing either of your search terms. It will return items that include both terms, but will also return items that contain only one of the terms.

This will give you a broader range of results.

OR can be used to link together synonyms. These are then placed in brackets to show that they are all the same concept.

• (cat OR kitten OR feline)
• (women OR female)

women AND Africa

Using AND will find items that contain both of your search terms, giving you a more specific set of results.

If you're getting too many results, using AND can be a good way to narrow your search.

women NOT Africa

Using NOT will find articles containing a particular term, but will exclude articles containing your second term.

Use this with caution - by excluding results you might miss out on key resources.

• Phrase searching
• Proximity searching

Sometimes your search may contain common words (i.e. development, communication) which will retrieve too many irrelevant records, even when using an AND search. On many databases, including Google, to look for a specific phrase, use inverted commas:

• "agricultural development"
• "foot and mouth"

Your search will only bring back items containing these exact phrases.

Some databases automatically perform a phrase search if you do not use any search operators. For example, "agriculture africa" is not a phrase used in English so you may not find any items on the subject. Use AND in between your search words to avoid this.

On Scopus to search for an exact phrase use { } e.g. {agricultural development}. Using quotes on Scopus will find your words in the same field (e.g., title) but not necessarily next to one another. In this database, you need to be very careful with those brackets - {heart-attack} and {heart attack} will return different results because the dash is included. Wildcards are searched as actual characters, e.g. {health care?} returns results such as: Who pays for health care?

Some databases use proximity operators, which are a more advanced search function. You can use these to tell the database how close one word must be to another and, in some cases, in what order. This makes a search more specific and excludes irrelevant records.

For instance, if you were searching for references about women in Africa, you might retrieve irrelevant records for items about women published in Africa. Performing a proximity search will only retrieve the two words in the same sentence, making your search more accurate.

Each database has its own way of proximity searching, often with multiple ways of doing it, so it's important to check the online help before you start . Here are some examples of the variety of possible searches:

• Web of Science : women  same Africa - retrieves records where the words 'women' and 'Africa' appear in the same sentence
• JSTOR : agricultural development ~5  - retrieves records where the words 'agricultural' and 'development' are within five words of one another
• Scopus : agricultural  W/2 development - retrieves records where the word 'agricultural' is within two words of the word 'development'. 

After completing your keywords search on a topic, you can move on to looking for appropriate subject headings.

Most databases have this controlled vocabulary feature (standardised subject headings or thesaurus terms - a bit like standard tags) which can help ensure you capture all the relevant studies; for example, MEDLINE, CENTRAL and PubMed use the exact same headings, which are called MeSH (Medical Subject Headings). Some of these headings will be the same in other related databases like CINAHL, but many of them will be slightly different, could be the same but have subtly different meanings, or not be there at all.

Not all databases have these types of subject headings - Web of Science and JSTOR don't allow you to search for subject headings like these, although you can of course search for subjects in them.

The easiest way to search for a subject heading is to go to the relevant area in the database that searches specifically for them; this might be called something like Thesaurus, Subject Headings, or similar. Then search for some of the words to do with your topic - not all of them at once, just a word on its own or a very simple phrase. Does this bring anything up? When you read the description, are you talking about the same thing?

You can then tell it to search for everything listed under that subject heading, then move on to looking for another subject heading. It's quite common for one topic to have several relevant headings.

Once you have found all the relevant headings, and made the database run searches for them, you will then combine them together using OR.

After you have found all the title/abstract/keywords for Topic A, and then all the relevant subject headings, you then combine those together using OR. You may need to go into the Search History section of the database to do this, and work out whether you can tick boxes next to your various searches to combine them, or have to type out something like "#1 OR #2".

This gives you a "super search" with everything in the database on that topic. It's likely to be a lot!

It might be that adding them together gives no extra results than the amount in either the keywords or the subject headings on their own. This is unusual, but not impossible:

You now go back to the start and for Topic B do the same title/abstract/keywords searches, then the relevant subject headings searches, then combine them as above. Then Topic C, and so on. Again, each of these super searches may have very high numbers - possibly millions.

Finally, you then combine all these super searches together, but this time using AND; they need to mention all the topics. It's possible that there are no articles in that database that mention all those things - the more subjects you AND together, the less results you are likely to find. However, it's also possible to end up with zero as there is a mistake in your search, and in most cases having zero results won't allow you to write your paper or thesis. So contact us if you think you have too few or two many results, and we can advise.

Methodological search filters are search terms or strategies that identify a topic or aspect. They are predefined, tried and tested filters which can be applied to a search.

Study types: 'systematic reviews', 'Randomised Controlled Trials'

Age groups: 'children', 'elderly'

Language: 'English'

They are available to select via the results filters displayed alongside your results and are normally applied at the very end of your search . For instance, on PubMed after running your results it is possible to limit by 'Ages' which gives predefined groupings such as 'Infant: birth-23 months'. These limits and filters are not always the same across the databases, so do be careful .

• << Previous: Finding the Literature
• Next: Managing Your Research >>
• Last Updated: Oct 10, 2023 1:52 PM
• URL: https://libguides.tcd.ie/literature-reviews

A Guide to Evidence Synthesis: 4. Write a Search Strategy

• Meet Our Team
• Our Published Reviews and Protocols
• What is Evidence Synthesis?
• Types of Evidence Synthesis
• Evidence Synthesis Across Disciplines
• Finding and Appraising Existing Systematic Reviews
• 0. Develop a Protocol
• 1. Draft your Research Question
• 2. Select Databases
• 3. Select Grey Literature Sources
• 4. Write a Search Strategy
• 5. Register a Protocol
• 6. Translate Search Strategies
• 7. Citation Management
• 8. Article Screening
• 9. Risk of Bias Assessment
• 10. Data Extraction
• 11. Synthesize, Map, or Describe the Results
• Evidence Synthesis Institute for Librarians
• Open Access Evidence Synthesis Resources

Video: Databases and search strategies (3:40 minutes)

Writing a Search Strategy

It is recommended that you work with a librarian to help you design comprehensive search strategies across a variety of databases. Writing a successful search strategy takes an intimate knowledge of bibliographic databases.  

Using Boolean logic is an important component of writing a search strategy: 

• "AND" narrows the search, e.g.  children AND exercise
• "OR" broadens the search, e.g.  (children OR adolescents) AND (exercise OR diet) 
• "NOT" excludes terms, e.g.  exercise NOT diet 
• "*" at the root of a word finds all forms of that word, e.g.  (child* OR adolescen*) AND (exercise* OR diet*)
• parentheses ensure all terms will be searched together as a set 
• quotations around a phrase searches that exact phrase, e.g.  (child* OR adolescen* OR "young adult*") 

Evidence Synthesis Search Strategy Examples

Agriculture example: .

• Research question:  What are the strategies that farmer organizations use, and what impacts do those strategies have on small-scale producers in Sub Saharan Africa and India? 
• Key concepts from the question combined with AND:  (farmer organizations) AND (Sub-Saharan Africa OR India) 
• Protocol and search strategies for this question in CAB Abstracts, Scopus, EconLit, and grey literature
• Published scoping review for this question

Nutrition Example: 

• Research question:  What are the health benefits and safety of folic acid fortification of wheat and maize flour (i.e. alone or in combination with other micronutrients) on folate status and health outcomes in the overall population, compared to wheat or maize flour without folic acid (or no intervention)? 
• Key concepts from the question combined with AND:  (folic acid) AND (fortification) 
• Protocol on PROSPERO
• Published systematic review for this question with search strategies used in 14 databases

Search Strategy Template and Filters

• Human Studies Filter
• Randomized Controlled Trial Filters
• Other Methodology Search Filters

If you want to exclude animal studies from your search results, you may add a "human studies filter" to the end of your search strategy. This approach works best with databases that use Medical Subject Headings (MeSH) or other controlled vocabulary. You can see an example of how this was used in the MEDLINE(Ovid) search strategy of this published review (lines 13-14).

A simplified explanation of this filter can be seen below:

Add the following lines to the end of your search strategy to filter for randomized controlled trials. These are "validated search filters" meaning they have been tested for sensitivity and specificity, and the results of those tests have been published as a scientific article. The ISSG Search Filters Resource provides validated search filters for many other study design types. 

Highly Sensitive MEDLINE (via PubMed) Filter from Cochrane  

(randomized controlled trial [pt] OR controlled clinical trial [pt] OR randomized [tiab] OR placebo [tiab] OR drug therapy [sh] OR randomly [tiab] OR trial [tiab] OR groups [tiab])

Highly Sensitive MEDLINE (OVID) Filter from Cochrane 

((randomized controlled trial.pt. or controlled clinical trial.pt. or randomized.ab. or placebo.ab. or drug therapy.fs. or randomly.ab. or trial.ab. or groups.ab.) not (exp animals/ not humans.sh.)) ​

CINAHL Filter from Cochrane 

TX allocat* random* OR (MH "Quantitative Studies") OR (MH "Placebos") OR TX placebo* OR TX random* allocat* OR (MH "Random Assignment") OR TX randomi* control* trial* OR TX ( (singl* n1 blind*) OR (singl* n1 mask*) ) OR TX ( (doubl* n1 blind*) OR (doubl* n1 mask*) ) OR TX ( (tripl* n1 blind*) OR (tripl* n1 mask*) ) OR TX ( (trebl* n1 blind*) OR (trebl* n1 mask*) ) OR TX clinic* n1 trial* OR PT Clinical trial OR (MH "Clinical Trials+")

PsycINFO Filter from ProQuest:

SU.EXACT("Treatment Effectiveness Evaluation") OR SU.EXACT.EXPLODE("Treatment Outcomes") OR SU.EXACT("Placebo") OR SU.EXACT("Followup Studies") OR placebo* OR random* OR "comparative stud*" OR  clinical NEAR/3 trial* OR research NEAR/3 design OR evaluat* NEAR/3 stud* OR prospectiv* NEAR/3 stud* OR (singl* OR doubl* OR trebl* OR tripl*) NEAR/3 (blind* OR mask*)

Web Of Science (WoS) Filter from University of Alberta - Not Validated

TS= clinical trial* OR TS=research design OR TS=comparative stud* OR TS=evaluation stud* OR TS=controlled trial* OR TS=follow-up stud* OR TS=prospective stud* OR TS=random* OR TS=placebo* OR TS=(single blind*) OR TS=(double blind*)

Scopus Filter from Children's Mercy Kansas City

TITLE-ABS-KEY((clinic* w/1 trial*) OR (randomi* w/1 control*) OR (randomi* w/2 trial*) OR (random* w/1 assign*) OR (random* w/1 allocat*) OR (control* w/1 clinic*) OR (control* w/1 trial) OR placebo* OR (Quantitat* w/1 Stud*) OR (control* w/1 stud*) OR (randomi* w/1 stud*) OR (singl* w/1 blind*) or (singl* w/1 mask*) OR (doubl* w/1 blind*) OR (doubl* w/1 mask*) OR (tripl* w/1 blind*) OR (tripl* w/1 mask*) OR (trebl* w/1 blind*) OR (trebl* w/1 mask*)) AND NOT (SRCTYPE(b) OR SRCTYPE(k) OR SRCTYPE(p) OR SRCTYPE(r) OR SRCTYPE(d) OR DOCTYPE(ab) OR DOCTYPE(bk) OR DOCTYPE(ch) OR DOCTYPE(bz) OR DOCTYPE(cr) OR DOCTYPE(ed) OR DOCTYPE(er) OR DOCTYPE(le) OR DOCTYPE(no) OR DOCTYPE(pr) OR DOCTYPE(rp) OR DOCTYPE(re) OR DOCTYPE(sh))

Sources and more information:

• Cochrane Handbook for Systematic Reviews of Interventions
• Cochrane RCT Filters for Different Databases
• American University of Beirut University Libraries Search Filters / Hedges
• Methodology Search Filters by Study Design - Countway Library of Medicine, Harvard University Filters for RCTs, CCTs, Non-randomized/observational designs, and tests of diagnostic accuracy.
• Search Filters - American University of Beirut University Libraries Filters for RCTs, GUIDELINEs, systematic reviews, qualitative studies, etc.

Pre-generated queries in Scopus for the UN Sustainable Development Goals

Pre-written SDG search strategies available in Scopus 

Scopus, a multidisciplinary research database, provides pre-written search strategies to capture articles on topics about each of the 17 United Nations Sustainable Development Goals  (SDGs). These search strategies were updated in 2023 and are no longer available directly on "Advanced Document Search". To use these SDG search strategies:

• Go to the Elsevier 2023 Sustainable Development Goals (SDGs) Mapping page.
• Under Files , click on the SDG 2023 Queries folder.
• Download the .txt file for each pre-written search strategy you are interested in. You will need to know the number of the SDG of interest (e.g., SDG01.txt is for SDG 1: No Poverty). This .txt file will contain the entire search string for the SDG, already written in Scopus syntax .
• In Scopus , click on "Advanced Document Search".
• Copy and paste the pre-written SDG search strategy into the search field.

More about the Sustainable Development Goals: 

" The 2030 Agenda for Sustainable Development,  adopted by all United Nations Member States in 2015, provides a shared blueprint for peace and prosperity for people and the planet, now and into the future. At its heart are the 17 Sustainable Development Goals (SDGs), which are an urgent call for action by all countries - developed and developing - in a global partnership. They recognize that ending poverty and other deprivations must go hand-in-hand with strategies that improve health and education, reduce inequality, and spur economic growth – all while tackling climate change and working to preserve our oceans and forests."

Source:  https://sdgs.un.org/goals 

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Conducting a Literature Review

• Literature Review
• Developing a Topic
• Planning Your Literature Review

Developing a Search Strategy

• Managing Citations
• Critical Appraisal Tools
• Writing a Literature Review

A search strategy is an organized structure of key terms used to search a database. The search strategy combines the key concepts of your search question in order to retrieve accurate results.

Your search strategy will account for all:

• possible search terms
• keywords and phrases
• truncated and wildcard variations of search terms
• subject headings (where applicable)

Each database works differently so you need to adapt your search strategy for each database. You may wish to develop a number of separate search strategies if your research covers several different areas. 

It is a good idea to test your strategies and refine them after you have reviewed the search results.

This is a sample planner to develop your search terms from a PICO format

Identifying Search Terms

Once you have developed your research question or chosen your topic you can begin to brainstorm terms to use in your database search.

• Brainstorm terms authors or indexers might use to describe your topic
• Make a list of terminology and relevant terms to use in your search
• Include synonyms or similar terms to combine using the Boolean operator OR
• Search for controlled vocabulary in the databases i.e. search PubMed for MeSH terms

Combine the Elements of Your PICO Question with Boolean Operators

Boolean Operators (Using AND, OR NOT):

Boolean logic is a building block of many computer applications and is an important concept in database searching.  Using the correct Boolean operator can make all the difference in a successful search.

AND, OR, NOT

There are three basic Boolean search commands:  AND ,  OR  and  NOT .

• AND  searches find all of the search terms.  For example, searching on dengue  AND  malaria  AND  zika  returns only results that contain all three search terms.  Very limited results.
• OR  searches find one term or the other.  Searching on dengue  OR  malaria  OR  zika returns all items that contain any of the three search terms.  Returns a large number of results.
• NOT  eliminates items that contain the specified term.  Searching on malaria  NOT  zika returns items that are about malaria, but will specifically  NOT  return items that contain the word zika.  This is a way to fine-tune results. Note:  sometimes  AND NOT  is used; serves the same function as  NOT

Using Boolean Search with Exact Phrases:

If you're searching for a phrase rather than just a single word, you can group the words together with quotation marks.  Searching on "dengue fever" will return only items with that exact phrase.  

When to use Parentheses?

Think of your search in concepts, then put those concepts inside parentheses.  Different databases have different rules about combining searches.  To make sure you get the search you want, use parentheses - every database follows those rules.

Run a Preliminary Search

Look at titles and publication dates to decide which articles you want to look at in depth.

• Select an article and begin the skimming and scanning process.
• If the list has too many irrelevant results, consider selecting different keywords and revising your search.
• If the list has too many results, consider setting date limiters or narrowing your results by searching phrases instead of keywords.
• If the list has too few results, consider selecting different keywords

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Literature Reviews & Search Strategies

• Defining the Literature Review
• Types of Literature Reviews
• Choosing Databases

Overview of Search Strategies

Search strategies, subject searching, example: iteratively developing + using keywords, demonstration: developing keywords from a question, demonstration: an advanced search.

• Organizing Your Literature
• Books: Research Design & Scholarly Writing
• Recommended Tutorials

There are many ways to find literature for your review, and we recommend that you use a combination of strategies - keeping in mind that you're going to be searching multiple times in a variety of ways, using different databases and resources. Searching the literature is not a straightforward, linear process - it's iterative (translation: you'll search multiple times, modifying your strategies as you go, and sometimes it'll be frustrating). 

• Known Item Searching
• Citation Jumping

Some form of a keyword search is the way most of us get at scholarly articles in database - it's a great approach! Make sure you're familiar with these librarian strategies to get the most out of your searches.

Figuring out the best keywords for your research topic/question is a process - you'll start with one or a few words and then shift, adapt, and expand them as you start finding source that describe the topic using other words. Your search terms are the bridge between known topics and the unknowns of your research question - so sometimes one specific word will be enough, sometimes you'll need several different words to describe a concept AND you'll need to connect that concept to a second (and/or third) concept.

The number and specificity of your search terms depend on your topic and the scope of your literature review.

Connect Keywords Using Boolean

Make the database work more.

...uses the asterisk (*) to end a word at its core, allowing you to retrieve many more documents containing variations of the search term.  Example: educat* will find educate, educates, education, educators, educating and more.

Phrase Searching

...is when you put quotations marks around two or more words, so that the database looks for those words in that exact order. Examples: "higher education," "public health" and "pharmaceutical industry."

Controlled Vocabulary

... is when you use the terms the database uses to describe what each article is about as search terms. Searching using controlled vocabularies is a great way to get at everything on a topic in a database.  

Databases and search engines are probably going to bring back a lot of results - more than a human can realistically go through. Instead of trying to manually read and sort them all, use the filters in each database to remove the stuff you wouldn't use anyway (ie it's outside the scope of your project).

To make sure you're consistent between searches and databases, write down the filters you're using.

A Few Filters to Try

Once you know you have a good article , there are a lot of useful parts to it - far beyond the content.

Not sure where to start? Try course readings and other required materials.

Useful Parts of a Good Article

Ways to use citations.

• Interactive Tutorial: Searching Cited and Citing Practice starting your search at an article and using the references to gather additional sources.

Your search results don't have to be frozen in the moment you search! There are a few things you can set up to keep your search going automatically.

Searching using subject headings is a comprehensive search strategy that requires some planning and topic knowledge. Work through this PubMed tutorial for an introduction to this important approach to searching.

Through these videos and the accompanying PDF, you'll see an example of starting with a potential research question and developing search terms through brainstorming and keyword searching.

• Slidedeck: Keywords and Advanced Search PowerPoint slides to accompany the two demonstration videos on developing keywords from a question, and doing an advanced search.
• << Previous: Choosing Databases
• Next: Organizing Your Literature >>
• Last Updated: Jun 14, 2023 11:18 AM
• URL: https://mcphs.libguides.com/litreviews

• Study and research support
• Literature searching

Literature searching explained

Develop a search strategy.

A search strategy is an organised structure of key terms used to search a database. The search strategy combines the key concepts of your search question in order to retrieve accurate results.

Your search strategy will account for all:

• possible search terms
• keywords and phrases
• truncated and wildcard variations of search terms
• subject headings (where applicable)

Each database works differently so you need to adapt your search strategy for each database. You may wish to develop a number of separate search strategies if your research covers several different areas.

It is a good idea to test your strategies and refine them after you have reviewed the search results.

How a search strategy looks in practice

Take a look at this example literature search in PsycINFO (PDF) about self-esteem.

The example shows the subject heading and keyword searches that have been carried out for each concept within our research question and how they have been combined using Boolean operators. It also shows where keyword techniques like truncation, wildcards and adjacency searching have been used.

Search strategy techniques

The next sections show some techniques you can use to develop your search strategy.

Skip straight to:

• Choosing search terms
• Searching with keywords
• Searching for exact phrases
• Using truncated and wildcard searches

Searching with subject headings

• Using Boolean logic

Citation searching

Choose search terms.

Concepts can be expressed in different ways eg “self-esteem” might be referred to as “self-worth”. Your aim is to consider each of your concepts and come up with a list of the different ways they could be expressed.

To find alternative keywords or phrases for your concepts try the following:

• Use a thesaurus to identify synonyms.
• Search for your concepts on a search engine like Google Scholar, scanning the results for alternative words and phrases.
• Examine relevant abstracts or articles for alternative words, phrases and subject headings (if the database uses subject headings).

When you've done this, you should have lists of words and phrases for each concept as in this completed PICO model (PDF) or this example concept map (PDF).

As you search and scan articles and abstracts, you may discover different key terms to enhance your search strategy.

Using truncation and wildcards can save you time and effort by finding alternative keywords.

Search with keywords

Keywords are free text words and phrases. Database search strategies use a combination of free text and subject headings (where applicable).

A keyword search usually looks for your search terms in the title and abstract of a reference. You may wish to search in title fields only if you want a small number of specific results.

Some databases will find the exact word or phrase, so make sure your spelling is accurate or you will miss references.

Search for the exact phrase

If you want words to appear next to each other in an exact phrase, use quotation marks, eg “self-esteem”.

Phrase searching decreases the number of results you get and makes your results more relevant. Most databases allow you to search for phrases, but check the database guide if you are unsure.

Truncation and wildcard searches

You can use truncated and wildcard searches to find variations of your search term. Truncation is useful for finding singular and plural forms of words and variant endings.

Many databases use an asterisk (*) as their truncation symbol. Check the database help section if you are not sure which symbol to use. For example, “therap*” will find therapy, therapies, therapist or therapists. A wildcard finds variant spellings of words. Use it to search for a single character, or no character.

Check the database help section to see which symbol to use as a wildcard.

Wildcards are useful for finding British and American spellings, for example: “behavio?r” in Medline will find both behaviour and behavior.

There are sometimes different symbols to find a variable single character. For example, in the Medline database, “wom#n” will find woman and also women.

Use adjacency searching for more accurate results

You can specify how close two words appear together in your search strategy. This can make your results more relevant; generally the closer two words appear to each other, the closer the relationship is between them.

Commands for adjacency searching differ among databases, so make sure you consult database guides.

In OvidSP databases (like Medline), searching for “physician ADJ3 relationship” will find both physician and relationship within two major words of each other, in any order. This finds more papers than "physician relationship".

Using this adjacency retrieves papers with phrases like "physician patient relationship", "patient physician relationship", "relationship of the physician to the patient" and so on.

Database subject headings are controlled vocabulary terms that a database uses to describe what an article is about.

Watch our 3-minute introduction to subject headings video . You can also  View the video using Microsoft Stream (link opens in a new window, available for University members only).

Using appropriate subject headings enhances your search and will help you to find more results on your topic. This is because subject headings find articles according to their subject, even if the article does not use your chosen key words.

You should combine both subject headings and keywords in your search strategy for each of the concepts you identify. This is particularly important if you are undertaking a systematic review or an in-depth piece of work

Subject headings may vary between databases, so you need to investigate each database separately to find the subject headings they use. For example, for Medline you can use MeSH (Medical Subject Headings) and for Embase you can use the EMTREE thesaurus.

SEARCH TIP: In Ovid databases, search for a known key paper by title, select the "complete reference" button to see which subject headings the database indexers have given that article, and consider adding relevant ones to your own search strategy.

Use Boolean logic to combine search terms

Boolean operators (AND, OR and NOT) allow you to try different combinations of search terms or subject headings.

Databases often show Boolean operators as buttons or drop-down menus that you can click to combine your search terms or results.

The main Boolean operators are:

OR is used to find articles that mention either of the topics you search for.

AND is used to find articles that mention both of the searched topics.

NOT excludes a search term or concept. It should be used with caution as you may inadvertently exclude relevant references.

For example, searching for “self-esteem NOT eating disorders” finds articles that mention self-esteem but removes any articles that mention eating disorders.

Citation searching is a method to find articles that have been cited by other publications.

Use citation searching (or cited reference searching) to:

• find out whether articles have been cited by other authors
• find more recent papers on the same or similar subject
• discover how a known idea or innovation has been confirmed, applied, improved, extended, or corrected
• help make your literature review more comprehensive.

You can use cited reference searching in:

• OvidSP databases
• Google Scholar
• Web of Science

Cited reference searching can complement your literature search. However be careful not to just look at papers that have been cited in isolation. A robust literature search is also needed to limit publication bias.

Capstone Form and Style

Search strategy description samples: phd search strategy description sample, phd search strategy description sample.

In the example below, notes follow some of the paragraphs.

PhD Dissertation Example (Psychology)

Literature Search Strategy

I searched for relevant literature from the PsycINFO, Business Source Complete, PsycARTICLES, PsycBOOKS, PsycCRITIQUES, PsycEXTRA databases. The search was limited to peer-reviewed scholarly journals using the search terms psychological capital or PsyCap (611 results); mental time travel or thinking perspective (1,086 results); construal-level theory or temporal focus (1,372 results); safety performance or construction safety (8,408 results); and organizational citizenship behaviors or OCB (2,099 results). Next, the search was narrowed to articles published since 2006 using the same search terms across the same databases: psychological capital or PsyCap (553 results); mental time travel or thinking perspective (725 results); construal-level theory or temporal focus (786 results); safety performance or construction safety (2,176 results); and organizational citizenship behaviors (1,706 results).

In the second sentence in the previous paragraph, the student has cleverly incorporated the number of results, which is an important detail, in the list of search terms.

I then added filters by subject and/or classification to the search term groups. Specifically, the classification filters organizational behaviors, personality traits and processes, and industrial and organizational psychology were added to psychological capital or PsyCap (83 results); the classification filters cognitive process, organizational behaviors, personality traits and processes, and industrial and organizational psychology were added to  mental time travel  or  thinking perspective  (77 results) and to  construallevel theory  or  temporal focus  (116 results). The subject filters  construction projects ,  performance , and  job performance  were added to the search terms  safety performance  or  construction safety  (103 results). Last, the filters subject  organizational citizenship behaviors  and classification  organizational behavior  were added to OCBs (128 results).

In the previous paragraph, this thorough, step-by-step overview of the search process is helpful to readers and researchers who might be examining the same topic.

One last search across the same databases targeted peer-reviewed printed material that referred to a combination of the constructs of interest. Specifically, the search term  combinations were  psychological capital ,  PsyCap , and  safety (24 results);  psychological  capital  and  time orientation  or  time perspective , or  thinking perspective,  or  temporal perspective , or  temporal focus,  or  mental time travel , or  construal-level theory  (six  results);  accident , OR  safety , OR  construction site safety  and  time orientation , or  time  perspective , or  thinking perspective , or temporal perspective, or  temporal focus , or   mental time travel , or  construal-level theory  (155 results);  time perspective , or  thinking perspective , or  temporal perspective , or  temporal focus , or  mental time travel  or  construal-level theory  and  OCBs  (nine results).

The inclusion criteria for literature to be included in the review were as follows: (a) organizational-related articles, (b) non-medical-related articles, (c) relevance to the construction industry, and (d) written in English. The references list of selected articles led to seminal works from as far back as 1971 on temporal focus, construal-level theory (CLT), the theory of MindTime, mental time travel, safety performance models, and PsyCap. This research also included six books.

In the previous paragraph, additional information makes this a thorough overview of the search process.

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• Research Guides

Systematic Reviews

• Search Strategy
• Work with a Search Expert
• Covidence Review Software
• Types of Reviews
• Evidence in a Systematic Review
• Information Sources

Developing an Answerable Question

Creating a search strategy, identifying synonyms & related terms, keywords vs. index terms, combining search terms using boolean operators, a sr search strategy, search limits.

• Managing Records
• Selection Process
• Data Collection Process
• Study Risk of Bias Assessment
• Reporting Results
• For Search Professionals

Validated Search Filters

Depending on your topic, you may be able to save time in constructing your search by using specific search filters (also called "hedges") developed & validated by researchers in the Health Information Research Unit (HiRU) of McMaster University, under contract from the National Library of Medicine.  These filters can be found on

• PubMed’s Clinical Queries &  Health Services Research Queries pages
• Ovid Medline’s Clinical Queries  filters or here
• Embase  & PsycINFO
• EBSCOhost’s main search page for CINAHL (Clinical Queries category)
• HiRU’s Nephrology Filters page
• American U of Beirut, esp. for " humans" filters .
• Countway Library of Medicine methodology filters
• InterTASC Information Specialists' Sub-Group Search Filter Resource
• SIGN (Scottish Intercollegiate Guidelines Network) filters page

Why Create a Sensitive Search?

In many literature reviews, you try to balance the sensitivity of the search (how many potentially relevant articles you find) &  specificit y (how many definitely relevant articles  you find ), realizing that you will miss some.  In a systematic review, you want a very sensitive search:  you are trying to find any potentially relevant article.  A systematic review search will:

• contain many synonyms & variants of search terms
• use care in adding search filters
• search multiple resources, databases & grey literature, such as reports & clinical trials

PICO is a good framework to help clarify your systematic review question.

P -   Patient, Population or Problem: What are the important characteristics of the patients &/or problem?

I -  Intervention:  What you plan to do for the patient or problem?

C -  Comparison: What, if anything, is the alternative to the intervention?

O -  Outcome:  What is the outcome that you would like to measure?

Beyond PICO: the SPIDER tool for qualitative evidence synthesis.

5-SPICE: the application of an original framework for community health worker program design, quality improvement and research agenda setting.

A well constructed search strategy is the core of your systematic review and will be reported on in the methods section of your paper. The search strategy retrieves the majority of the studies you will assess for eligibility & inclusion. The quality of the search strategy also affects what items may have been missed.  Informationists can be partners in this process.

For a systematic review, it is important to broaden your search to maximize the retrieval of relevant results.

Use keywords:  How other people might describe a topic?

Identify the appropriate index terms (subject headings) for your topic.

• Index terms differ by database (MeSH, or  Medical Subject Headings ,   Emtree terms , Subject headings) are assigned by experts based on the article's content.
• Check the indexing of sentinel articles (3-6 articles that are fundamental to your topic).  Sentinel articles can also be used to  test your search results.

Include spelling variations (e.g., behavior, behaviour ).  

Both types of  search terms are useful & both should be used in your search.

Keywords help to broaden your results.  They will be searched for at least in journal titles, author names, article titles, & article abstracts.  They can also be tagged to search all text.

Index/subject terms  help to focus your search appropriately, looking for items that have had a specific term applied by an indexer.

Boolean operators let you combine search terms in specific ways to broaden or narrow your results.

An example of a search string for one concept in a systematic review.

In this example from a PubMed search, [mh] = MeSH &  [tiab] = Title/Abstract, a more focused version of a keyword search.

A typical database search limit allows you to narrow results so that you retrieve articles that are most relevant to your research question. Limit types vary by database & include:

• Article/publication type
• Publication dates

In a systematic review search, you should use care when applying limits, as you may lose articles inadvertently.  For more information, see, particularly regarding language & format limits.     Cochrane 2008 6.4.9

• Open access
• Published: 14 August 2018

Defining the process to literature searching in systematic reviews: a literature review of guidance and supporting studies

• Chris Cooper   ORCID: orcid.org/0000-0003-0864-5607 1 ,
• Andrew Booth 2 ,
• Jo Varley-Campbell 1 ,
• Nicky Britten 3 &
• Ruth Garside 4  

BMC Medical Research Methodology volume  18 , Article number:  85 ( 2018 ) Cite this article

205k Accesses

206 Citations

117 Altmetric

Metrics details

Systematic literature searching is recognised as a critical component of the systematic review process. It involves a systematic search for studies and aims for a transparent report of study identification, leaving readers clear about what was done to identify studies, and how the findings of the review are situated in the relevant evidence.

Information specialists and review teams appear to work from a shared and tacit model of the literature search process. How this tacit model has developed and evolved is unclear, and it has not been explicitly examined before.

The purpose of this review is to determine if a shared model of the literature searching process can be detected across systematic review guidance documents and, if so, how this process is reported in the guidance and supported by published studies.

A literature review.

Two types of literature were reviewed: guidance and published studies. Nine guidance documents were identified, including: The Cochrane and Campbell Handbooks. Published studies were identified through ‘pearl growing’, citation chasing, a search of PubMed using the systematic review methods filter, and the authors’ topic knowledge.

The relevant sections within each guidance document were then read and re-read, with the aim of determining key methodological stages. Methodological stages were identified and defined. This data was reviewed to identify agreements and areas of unique guidance between guidance documents. Consensus across multiple guidance documents was used to inform selection of ‘key stages’ in the process of literature searching.

Eight key stages were determined relating specifically to literature searching in systematic reviews. They were: who should literature search, aims and purpose of literature searching, preparation, the search strategy, searching databases, supplementary searching, managing references and reporting the search process.

Conclusions

Eight key stages to the process of literature searching in systematic reviews were identified. These key stages are consistently reported in the nine guidance documents, suggesting consensus on the key stages of literature searching, and therefore the process of literature searching as a whole, in systematic reviews. Further research to determine the suitability of using the same process of literature searching for all types of systematic review is indicated.

Peer Review reports

Systematic literature searching is recognised as a critical component of the systematic review process. It involves a systematic search for studies and aims for a transparent report of study identification, leaving review stakeholders clear about what was done to identify studies, and how the findings of the review are situated in the relevant evidence.

Information specialists and review teams appear to work from a shared and tacit model of the literature search process. How this tacit model has developed and evolved is unclear, and it has not been explicitly examined before. This is in contrast to the information science literature, which has developed information processing models as an explicit basis for dialogue and empirical testing. Without an explicit model, research in the process of systematic literature searching will remain immature and potentially uneven, and the development of shared information models will be assumed but never articulated.

One way of developing such a conceptual model is by formally examining the implicit “programme theory” as embodied in key methodological texts. The aim of this review is therefore to determine if a shared model of the literature searching process in systematic reviews can be detected across guidance documents and, if so, how this process is reported and supported.

Identifying guidance

Key texts (henceforth referred to as “guidance”) were identified based upon their accessibility to, and prominence within, United Kingdom systematic reviewing practice. The United Kingdom occupies a prominent position in the science of health information retrieval, as quantified by such objective measures as the authorship of papers, the number of Cochrane groups based in the UK, membership and leadership of groups such as the Cochrane Information Retrieval Methods Group, the HTA-I Information Specialists’ Group and historic association with such centres as the UK Cochrane Centre, the NHS Centre for Reviews and Dissemination, the Centre for Evidence Based Medicine and the National Institute for Clinical Excellence (NICE). Coupled with the linguistic dominance of English within medical and health science and the science of systematic reviews more generally, this offers a justification for a purposive sample that favours UK, European and Australian guidance documents.

Nine guidance documents were identified. These documents provide guidance for different types of reviews, namely: reviews of interventions, reviews of health technologies, reviews of qualitative research studies, reviews of social science topics, and reviews to inform guidance.

Whilst these guidance documents occasionally offer additional guidance on other types of systematic reviews, we have focused on the core and stated aims of these documents as they relate to literature searching. Table  1 sets out: the guidance document, the version audited, their core stated focus, and a bibliographical pointer to the main guidance relating to literature searching.

Once a list of key guidance documents was determined, it was checked by six senior information professionals based in the UK for relevance to current literature searching in systematic reviews.

Identifying supporting studies

In addition to identifying guidance, the authors sought to populate an evidence base of supporting studies (henceforth referred to as “studies”) that contribute to existing search practice. Studies were first identified by the authors from their knowledge on this topic area and, subsequently, through systematic citation chasing key studies (‘pearls’ [ 1 ]) located within each key stage of the search process. These studies are identified in Additional file  1 : Appendix Table 1. Citation chasing was conducted by analysing the bibliography of references for each study (backwards citation chasing) and through Google Scholar (forward citation chasing). A search of PubMed using the systematic review methods filter was undertaken in August 2017 (see Additional file 1 ). The search terms used were: (literature search*[Title/Abstract]) AND sysrev_methods[sb] and 586 results were returned. These results were sifted for relevance to the key stages in Fig.  1 by CC.

The key stages of literature search guidance as identified from nine key texts

Extracting the data

To reveal the implicit process of literature searching within each guidance document, the relevant sections (chapters) on literature searching were read and re-read, with the aim of determining key methodological stages. We defined a key methodological stage as a distinct step in the overall process for which specific guidance is reported, and action is taken, that collectively would result in a completed literature search.

The chapter or section sub-heading for each methodological stage was extracted into a table using the exact language as reported in each guidance document. The lead author (CC) then read and re-read these data, and the paragraphs of the document to which the headings referred, summarising section details. This table was then reviewed, using comparison and contrast to identify agreements and areas of unique guidance. Consensus across multiple guidelines was used to inform selection of ‘key stages’ in the process of literature searching.

Having determined the key stages to literature searching, we then read and re-read the sections relating to literature searching again, extracting specific detail relating to the methodological process of literature searching within each key stage. Again, the guidance was then read and re-read, first on a document-by-document-basis and, secondly, across all the documents above, to identify both commonalities and areas of unique guidance.

Results and discussion

Our findings.

We were able to identify consensus across the guidance on literature searching for systematic reviews suggesting a shared implicit model within the information retrieval community. Whilst the structure of the guidance varies between documents, the same key stages are reported, even where the core focus of each document is different. We were able to identify specific areas of unique guidance, where a document reported guidance not summarised in other documents, together with areas of consensus across guidance.

Unique guidance

Only one document provided guidance on the topic of when to stop searching [ 2 ]. This guidance from 2005 anticipates a topic of increasing importance with the current interest in time-limited (i.e. “rapid”) reviews. Quality assurance (or peer review) of literature searches was only covered in two guidance documents [ 3 , 4 ]. This topic has emerged as increasingly important as indicated by the development of the PRESS instrument [ 5 ]. Text mining was discussed in four guidance documents [ 4 , 6 , 7 , 8 ] where the automation of some manual review work may offer efficiencies in literature searching [ 8 ].

Agreement between guidance: Defining the key stages of literature searching

Where there was agreement on the process, we determined that this constituted a key stage in the process of literature searching to inform systematic reviews.

From the guidance, we determined eight key stages that relate specifically to literature searching in systematic reviews. These are summarised at Fig. 1 . The data extraction table to inform Fig. 1 is reported in Table  2 . Table 2 reports the areas of common agreement and it demonstrates that the language used to describe key stages and processes varies significantly between guidance documents.

For each key stage, we set out the specific guidance, followed by discussion on how this guidance is situated within the wider literature.

Key stage one: Deciding who should undertake the literature search

The guidance.

Eight documents provided guidance on who should undertake literature searching in systematic reviews [ 2 , 4 , 6 , 7 , 8 , 9 , 10 , 11 ]. The guidance affirms that people with relevant expertise of literature searching should ‘ideally’ be included within the review team [ 6 ]. Information specialists (or information scientists), librarians or trial search co-ordinators (TSCs) are indicated as appropriate researchers in six guidance documents [ 2 , 7 , 8 , 9 , 10 , 11 ].

How the guidance corresponds to the published studies

The guidance is consistent with studies that call for the involvement of information specialists and librarians in systematic reviews [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ] and which demonstrate how their training as ‘expert searchers’ and ‘analysers and organisers of data’ can be put to good use [ 13 ] in a variety of roles [ 12 , 16 , 20 , 21 , 24 , 25 , 26 ]. These arguments make sense in the context of the aims and purposes of literature searching in systematic reviews, explored below. The need for ‘thorough’ and ‘replicable’ literature searches was fundamental to the guidance and recurs in key stage two. Studies have found poor reporting, and a lack of replicable literature searches, to be a weakness in systematic reviews [ 17 , 18 , 27 , 28 ] and they argue that involvement of information specialists/ librarians would be associated with better reporting and better quality literature searching. Indeed, Meert et al. [ 29 ] demonstrated that involving a librarian as a co-author to a systematic review correlated with a higher score in the literature searching component of a systematic review [ 29 ]. As ‘new styles’ of rapid and scoping reviews emerge, where decisions on how to search are more iterative and creative, a clear role is made here too [ 30 ].

Knowing where to search for studies was noted as important in the guidance, with no agreement as to the appropriate number of databases to be searched [ 2 , 6 ]. Database (and resource selection more broadly) is acknowledged as a relevant key skill of information specialists and librarians [ 12 , 15 , 16 , 31 ].

Whilst arguments for including information specialists and librarians in the process of systematic review might be considered self-evident, Koffel and Rethlefsen [ 31 ] have questioned if the necessary involvement is actually happening [ 31 ].

Key stage two: Determining the aim and purpose of a literature search

The aim: Five of the nine guidance documents use adjectives such as ‘thorough’, ‘comprehensive’, ‘transparent’ and ‘reproducible’ to define the aim of literature searching [ 6 , 7 , 8 , 9 , 10 ]. Analogous phrases were present in a further three guidance documents, namely: ‘to identify the best available evidence’ [ 4 ] or ‘the aim of the literature search is not to retrieve everything. It is to retrieve everything of relevance’ [ 2 ] or ‘A systematic literature search aims to identify all publications relevant to the particular research question’ [ 3 ]. The Joanna Briggs Institute reviewers’ manual was the only guidance document where a clear statement on the aim of literature searching could not be identified. The purpose of literature searching was defined in three guidance documents, namely to minimise bias in the resultant review [ 6 , 8 , 10 ]. Accordingly, eight of nine documents clearly asserted that thorough and comprehensive literature searches are required as a potential mechanism for minimising bias.

The need for thorough and comprehensive literature searches appears as uniform within the eight guidance documents that describe approaches to literature searching in systematic reviews of effectiveness. Reviews of effectiveness (of intervention or cost), accuracy and prognosis, require thorough and comprehensive literature searches to transparently produce a reliable estimate of intervention effect. The belief that all relevant studies have been ‘comprehensively’ identified, and that this process has been ‘transparently’ reported, increases confidence in the estimate of effect and the conclusions that can be drawn [ 32 ]. The supporting literature exploring the need for comprehensive literature searches focuses almost exclusively on reviews of intervention effectiveness and meta-analysis. Different ‘styles’ of review may have different standards however; the alternative, offered by purposive sampling, has been suggested in the specific context of qualitative evidence syntheses [ 33 ].

What is a comprehensive literature search?

Whilst the guidance calls for thorough and comprehensive literature searches, it lacks clarity on what constitutes a thorough and comprehensive literature search, beyond the implication that all of the literature search methods in Table 2 should be used to identify studies. Egger et al. [ 34 ], in an empirical study evaluating the importance of comprehensive literature searches for trials in systematic reviews, defined a comprehensive search for trials as:

a search not restricted to English language;

where Cochrane CENTRAL or at least two other electronic databases had been searched (such as MEDLINE or EMBASE); and

at least one of the following search methods has been used to identify unpublished trials: searches for (I) conference abstracts, (ii) theses, (iii) trials registers; and (iv) contacts with experts in the field [ 34 ].

Tricco et al. (2008) used a similar threshold of bibliographic database searching AND a supplementary search method in a review when examining the risk of bias in systematic reviews. Their criteria were: one database (limited using the Cochrane Highly Sensitive Search Strategy (HSSS)) and handsearching [ 35 ].

Together with the guidance, this would suggest that comprehensive literature searching requires the use of BOTH bibliographic database searching AND supplementary search methods.

Comprehensiveness in literature searching, in the sense of how much searching should be undertaken, remains unclear. Egger et al. recommend that ‘investigators should consider the type of literature search and degree of comprehension that is appropriate for the review in question, taking into account budget and time constraints’ [ 34 ]. This view tallies with the Cochrane Handbook, which stipulates clearly, that study identification should be undertaken ‘within resource limits’ [ 9 ]. This would suggest that the limitations to comprehension are recognised but it raises questions on how this is decided and reported [ 36 ].

What is the point of comprehensive literature searching?

The purpose of thorough and comprehensive literature searches is to avoid missing key studies and to minimize bias [ 6 , 8 , 10 , 34 , 37 , 38 , 39 ] since a systematic review based only on published (or easily accessible) studies may have an exaggerated effect size [ 35 ]. Felson (1992) sets out potential biases that could affect the estimate of effect in a meta-analysis [ 40 ] and Tricco et al. summarize the evidence concerning bias and confounding in systematic reviews [ 35 ]. Egger et al. point to non-publication of studies, publication bias, language bias and MEDLINE bias, as key biases [ 34 , 35 , 40 , 41 , 42 , 43 , 44 , 45 , 46 ]. Comprehensive searches are not the sole factor to mitigate these biases but their contribution is thought to be significant [ 2 , 32 , 34 ]. Fehrmann (2011) suggests that ‘the search process being described in detail’ and that, where standard comprehensive search techniques have been applied, increases confidence in the search results [ 32 ].

Does comprehensive literature searching work?

Egger et al., and other study authors, have demonstrated a change in the estimate of intervention effectiveness where relevant studies were excluded from meta-analysis [ 34 , 47 ]. This would suggest that missing studies in literature searching alters the reliability of effectiveness estimates. This is an argument for comprehensive literature searching. Conversely, Egger et al. found that ‘comprehensive’ searches still missed studies and that comprehensive searches could, in fact, introduce bias into a review rather than preventing it, through the identification of low quality studies then being included in the meta-analysis [ 34 ]. Studies query if identifying and including low quality or grey literature studies changes the estimate of effect [ 43 , 48 ] and question if time is better invested updating systematic reviews rather than searching for unpublished studies [ 49 ], or mapping studies for review as opposed to aiming for high sensitivity in literature searching [ 50 ].

Aim and purpose beyond reviews of effectiveness

The need for comprehensive literature searches is less certain in reviews of qualitative studies, and for reviews where a comprehensive identification of studies is difficult to achieve (for example, in Public health) [ 33 , 51 , 52 , 53 , 54 , 55 ]. Literature searching for qualitative studies, and in public health topics, typically generates a greater number of studies to sift than in reviews of effectiveness [ 39 ] and demonstrating the ‘value’ of studies identified or missed is harder [ 56 ], since the study data do not typically support meta-analysis. Nussbaumer-Streit et al. (2016) have registered a review protocol to assess whether abbreviated literature searches (as opposed to comprehensive literature searches) has an impact on conclusions across multiple bodies of evidence, not only on effect estimates [ 57 ] which may develop this understanding. It may be that decision makers and users of systematic reviews are willing to trade the certainty from a comprehensive literature search and systematic review in exchange for different approaches to evidence synthesis [ 58 ], and that comprehensive literature searches are not necessarily a marker of literature search quality, as previously thought [ 36 ]. Different approaches to literature searching [ 37 , 38 , 59 , 60 , 61 , 62 ] and developing the concept of when to stop searching are important areas for further study [ 36 , 59 ].

The study by Nussbaumer-Streit et al. has been published since the submission of this literature review [ 63 ]. Nussbaumer-Streit et al. (2018) conclude that abbreviated literature searches are viable options for rapid evidence syntheses, if decision-makers are willing to trade the certainty from a comprehensive literature search and systematic review, but that decision-making which demands detailed scrutiny should still be based on comprehensive literature searches [ 63 ].

Key stage three: Preparing for the literature search

Six documents provided guidance on preparing for a literature search [ 2 , 3 , 6 , 7 , 9 , 10 ]. The Cochrane Handbook clearly stated that Cochrane authors (i.e. researchers) should seek advice from a trial search co-ordinator (i.e. a person with specific skills in literature searching) ‘before’ starting a literature search [ 9 ].

Two key tasks were perceptible in preparing for a literature searching [ 2 , 6 , 7 , 10 , 11 ]. First, to determine if there are any existing or on-going reviews, or if a new review is justified [ 6 , 11 ]; and, secondly, to develop an initial literature search strategy to estimate the volume of relevant literature (and quality of a small sample of relevant studies [ 10 ]) and indicate the resources required for literature searching and the review of the studies that follows [ 7 , 10 ].

Three documents summarised guidance on where to search to determine if a new review was justified [ 2 , 6 , 11 ]. These focused on searching databases of systematic reviews (The Cochrane Database of Systematic Reviews (CDSR) and the Database of Abstracts of Reviews of Effects (DARE)), institutional registries (including PROSPERO), and MEDLINE [ 6 , 11 ]. It is worth noting, however, that as of 2015, DARE (and NHS EEDs) are no longer being updated and so the relevance of this (these) resource(s) will diminish over-time [ 64 ]. One guidance document, ‘Systematic reviews in the Social Sciences’, noted, however, that databases are not the only source of information and unpublished reports, conference proceeding and grey literature may also be required, depending on the nature of the review question [ 2 ].

Two documents reported clearly that this preparation (or ‘scoping’) exercise should be undertaken before the actual search strategy is developed [ 7 , 10 ]).

The guidance offers the best available source on preparing the literature search with the published studies not typically reporting how their scoping informed the development of their search strategies nor how their search approaches were developed. Text mining has been proposed as a technique to develop search strategies in the scoping stages of a review although this work is still exploratory [ 65 ]. ‘Clustering documents’ and word frequency analysis have also been tested to identify search terms and studies for review [ 66 , 67 ]. Preparing for literature searches and scoping constitutes an area for future research.

Key stage four: Designing the search strategy

The Population, Intervention, Comparator, Outcome (PICO) structure was the commonly reported structure promoted to design a literature search strategy. Five documents suggested that the eligibility criteria or review question will determine which concepts of PICO will be populated to develop the search strategy [ 1 , 4 , 7 , 8 , 9 ]. The NICE handbook promoted multiple structures, namely PICO, SPICE (Setting, Perspective, Intervention, Comparison, Evaluation) and multi-stranded approaches [ 4 ].

With the exclusion of The Joanna Briggs Institute reviewers’ manual, the guidance offered detail on selecting key search terms, synonyms, Boolean language, selecting database indexing terms and combining search terms. The CEE handbook suggested that ‘search terms may be compiled with the help of the commissioning organisation and stakeholders’ [ 10 ].

The use of limits, such as language or date limits, were discussed in all documents [ 2 , 3 , 4 , 6 , 7 , 8 , 9 , 10 , 11 ].

Search strategy structure

The guidance typically relates to reviews of intervention effectiveness so PICO – with its focus on intervention and comparator - is the dominant model used to structure literature search strategies [ 68 ]. PICOs – where the S denotes study design - is also commonly used in effectiveness reviews [ 6 , 68 ]. As the NICE handbook notes, alternative models to structure literature search strategies have been developed and tested. Booth provides an overview on formulating questions for evidence based practice [ 69 ] and has developed a number of alternatives to the PICO structure, namely: BeHEMoTh (Behaviour of interest; Health context; Exclusions; Models or Theories) for use when systematically identifying theory [ 55 ]; SPICE (Setting, Perspective, Intervention, Comparison, Evaluation) for identification of social science and evaluation studies [ 69 ] and, working with Cooke and colleagues, SPIDER (Sample, Phenomenon of Interest, Design, Evaluation, Research type) [ 70 ]. SPIDER has been compared to PICO and PICOs in a study by Methley et al. [ 68 ].

The NICE handbook also suggests the use of multi-stranded approaches to developing literature search strategies [ 4 ]. Glanville developed this idea in a study by Whitting et al. [ 71 ] and a worked example of this approach is included in the development of a search filter by Cooper et al. [ 72 ].

Writing search strategies: Conceptual and objective approaches

Hausner et al. [ 73 ] provide guidance on writing literature search strategies, delineating between conceptually and objectively derived approaches. The conceptual approach, advocated by and explained in the guidance documents, relies on the expertise of the literature searcher to identify key search terms and then develop key terms to include synonyms and controlled syntax. Hausner and colleagues set out the objective approach [ 73 ] and describe what may be done to validate it [ 74 ].

The use of limits

The guidance documents offer direction on the use of limits within a literature search. Limits can be used to focus literature searching to specific study designs or by other markers (such as by date) which limits the number of studies returned by a literature search. The use of limits should be described and the implications explored [ 34 ] since limiting literature searching can introduce bias (explored above). Craven et al. have suggested the use of a supporting narrative to explain decisions made in the process of developing literature searches and this advice would usefully capture decisions on the use of search limits [ 75 ].

Key stage five: Determining the process of literature searching and deciding where to search (bibliographic database searching)

Table 2 summarises the process of literature searching as reported in each guidance document. Searching bibliographic databases was consistently reported as the ‘first step’ to literature searching in all nine guidance documents.

Three documents reported specific guidance on where to search, in each case specific to the type of review their guidance informed, and as a minimum requirement [ 4 , 9 , 11 ]. Seven of the key guidance documents suggest that the selection of bibliographic databases depends on the topic of review [ 2 , 3 , 4 , 6 , 7 , 8 , 10 ], with two documents noting the absence of an agreed standard on what constitutes an acceptable number of databases searched [ 2 , 6 ].

The guidance documents summarise ‘how to’ search bibliographic databases in detail and this guidance is further contextualised above in terms of developing the search strategy. The documents provide guidance of selecting bibliographic databases, in some cases stating acceptable minima (i.e. The Cochrane Handbook states Cochrane CENTRAL, MEDLINE and EMBASE), and in other cases simply listing bibliographic database available to search. Studies have explored the value in searching specific bibliographic databases, with Wright et al. (2015) noting the contribution of CINAHL in identifying qualitative studies [ 76 ], Beckles et al. (2013) questioning the contribution of CINAHL to identifying clinical studies for guideline development [ 77 ], and Cooper et al. (2015) exploring the role of UK-focused bibliographic databases to identify UK-relevant studies [ 78 ]. The host of the database (e.g. OVID or ProQuest) has been shown to alter the search returns offered. Younger and Boddy [ 79 ] report differing search returns from the same database (AMED) but where the ‘host’ was different [ 79 ].

The average number of bibliographic database searched in systematic reviews has risen in the period 1994–2014 (from 1 to 4) [ 80 ] but there remains (as attested to by the guidance) no consensus on what constitutes an acceptable number of databases searched [ 48 ]. This is perhaps because thinking about the number of databases searched is the wrong question, researchers should be focused on which databases were searched and why, and which databases were not searched and why. The discussion should re-orientate to the differential value of sources but researchers need to think about how to report this in studies to allow findings to be generalised. Bethel (2017) has proposed ‘search summaries’, completed by the literature searcher, to record where included studies were identified, whether from database (and which databases specifically) or supplementary search methods [ 81 ]. Search summaries document both yield and accuracy of searches, which could prospectively inform resource use and decisions to search or not to search specific databases in topic areas. The prospective use of such data presupposes, however, that past searches are a potential predictor of future search performance (i.e. that each topic is to be considered representative and not unique). In offering a body of practice, this data would be of greater practicable use than current studies which are considered as little more than individual case studies [ 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 ].

When to database search is another question posed in the literature. Beyer et al. [ 91 ] report that databases can be prioritised for literature searching which, whilst not addressing the question of which databases to search, may at least bring clarity as to which databases to search first [ 91 ]. Paradoxically, this links to studies that suggest PubMed should be searched in addition to MEDLINE (OVID interface) since this improves the currency of systematic reviews [ 92 , 93 ]. Cooper et al. (2017) have tested the idea of database searching not as a primary search method (as suggested in the guidance) but as a supplementary search method in order to manage the volume of studies identified for an environmental effectiveness systematic review. Their case study compared the effectiveness of database searching versus a protocol using supplementary search methods and found that the latter identified more relevant studies for review than searching bibliographic databases [ 94 ].

Key stage six: Determining the process of literature searching and deciding where to search (supplementary search methods)

Table 2 also summaries the process of literature searching which follows bibliographic database searching. As Table 2 sets out, guidance that supplementary literature search methods should be used in systematic reviews recurs across documents, but the order in which these methods are used, and the extent to which they are used, varies. We noted inconsistency in the labelling of supplementary search methods between guidance documents.

Rather than focus on the guidance on how to use the methods (which has been summarised in a recent review [ 95 ]), we focus on the aim or purpose of supplementary search methods.

The Cochrane Handbook reported that ‘efforts’ to identify unpublished studies should be made [ 9 ]. Four guidance documents [ 2 , 3 , 6 , 9 ] acknowledged that searching beyond bibliographic databases was necessary since ‘databases are not the only source of literature’ [ 2 ]. Only one document reported any guidance on determining when to use supplementary methods. The IQWiG handbook reported that the use of handsearching (in their example) could be determined on a ‘case-by-case basis’ which implies that the use of these methods is optional rather than mandatory. This is in contrast to the guidance (above) on bibliographic database searching.

The issue for supplementary search methods is similar in many ways to the issue of searching bibliographic databases: demonstrating value. The purpose and contribution of supplementary search methods in systematic reviews is increasingly acknowledged [ 37 , 61 , 62 , 96 , 97 , 98 , 99 , 100 , 101 ] but understanding the value of the search methods to identify studies and data is unclear. In a recently published review, Cooper et al. (2017) reviewed the literature on supplementary search methods looking to determine the advantages, disadvantages and resource implications of using supplementary search methods [ 95 ]. This review also summarises the key guidance and empirical studies and seeks to address the question on when to use these search methods and when not to [ 95 ]. The guidance is limited in this regard and, as Table 2 demonstrates, offers conflicting advice on the order of searching, and the extent to which these search methods should be used in systematic reviews.

Key stage seven: Managing the references

Five of the documents provided guidance on managing references, for example downloading, de-duplicating and managing the output of literature searches [ 2 , 4 , 6 , 8 , 10 ]. This guidance typically itemised available bibliographic management tools rather than offering guidance on how to use them specifically [ 2 , 4 , 6 , 8 ]. The CEE handbook provided guidance on importing data where no direct export option is available (e.g. web-searching) [ 10 ].

The literature on using bibliographic management tools is not large relative to the number of ‘how to’ videos on platforms such as YouTube (see for example [ 102 ]). These YouTube videos confirm the overall lack of ‘how to’ guidance identified in this study and offer useful instruction on managing references. Bramer et al. set out methods for de-duplicating data and reviewing references in Endnote [ 103 , 104 ] and Gall tests the direct search function within Endnote to access databases such as PubMed, finding a number of limitations [ 105 ]. Coar et al. and Ahmed et al. consider the role of the free-source tool, Zotero [ 106 , 107 ]. Managing references is a key administrative function in the process of review particularly for documenting searches in PRISMA guidance.

Key stage eight: Documenting the search

The Cochrane Handbook was the only guidance document to recommend a specific reporting guideline: Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) [ 9 ]. Six documents provided guidance on reporting the process of literature searching with specific criteria to report [ 3 , 4 , 6 , 8 , 9 , 10 ]. There was consensus on reporting: the databases searched (and the host searched by), the search strategies used, and any use of limits (e.g. date, language, search filters (The CRD handbook called for these limits to be justified [ 6 ])). Three guidance documents reported that the number of studies identified should be recorded [ 3 , 6 , 10 ]. The number of duplicates identified [ 10 ], the screening decisions [ 3 ], a comprehensive list of grey literature sources searched (and full detail for other supplementary search methods) [ 8 ], and an annotation of search terms tested but not used [ 4 ] were identified as unique items in four documents.

The Cochrane Handbook was the only guidance document to note that the full search strategies for each database should be included in the Additional file 1 of the review [ 9 ].

All guidance documents should ultimately deliver completed systematic reviews that fulfil the requirements of the PRISMA reporting guidelines [ 108 ]. The guidance broadly requires the reporting of data that corresponds with the requirements of the PRISMA statement although documents typically ask for diverse and additional items [ 108 ]. In 2008, Sampson et al. observed a lack of consensus on reporting search methods in systematic reviews [ 109 ] and this remains the case as of 2017, as evidenced in the guidance documents, and in spite of the publication of the PRISMA guidelines in 2009 [ 110 ]. It is unclear why the collective guidance does not more explicitly endorse adherence to the PRISMA guidance.

Reporting of literature searching is a key area in systematic reviews since it sets out clearly what was done and how the conclusions of the review can be believed [ 52 , 109 ]. Despite strong endorsement in the guidance documents, specifically supported in PRISMA guidance, and other related reporting standards too (such as ENTREQ for qualitative evidence synthesis, STROBE for reviews of observational studies), authors still highlight the prevalence of poor standards of literature search reporting [ 31 , 110 , 111 , 112 , 113 , 114 , 115 , 116 , 117 , 118 , 119 ]. To explore issues experienced by authors in reporting literature searches, and look at uptake of PRISMA, Radar et al. [ 120 ] surveyed over 260 review authors to determine common problems and their work summaries the practical aspects of reporting literature searching [ 120 ]. Atkinson et al. [ 121 ] have also analysed reporting standards for literature searching, summarising recommendations and gaps for reporting search strategies [ 121 ].

One area that is less well covered by the guidance, but nevertheless appears in this literature, is the quality appraisal or peer review of literature search strategies. The PRESS checklist is the most prominent and it aims to develop evidence-based guidelines to peer review of electronic search strategies [ 5 , 122 , 123 ]. A corresponding guideline for documentation of supplementary search methods does not yet exist although this idea is currently being explored.

How the reporting of the literature searching process corresponds to critical appraisal tools is an area for further research. In the survey undertaken by Radar et al. (2014), 86% of survey respondents (153/178) identified a need for further guidance on what aspects of the literature search process to report [ 120 ]. The PRISMA statement offers a brief summary of what to report but little practical guidance on how to report it [ 108 ]. Critical appraisal tools for systematic reviews, such as AMSTAR 2 (Shea et al. [ 124 ]) and ROBIS (Whiting et al. [ 125 ]), can usefully be read alongside PRISMA guidance, since they offer greater detail on how the reporting of the literature search will be appraised and, therefore, they offer a proxy on what to report [ 124 , 125 ]. Further research in the form of a study which undertakes a comparison between PRISMA and quality appraisal checklists for systematic reviews would seem to begin addressing the call, identified by Radar et al., for further guidance on what to report [ 120 ].

Limitations

Other handbooks exist.

A potential limitation of this literature review is the focus on guidance produced in Europe (the UK specifically) and Australia. We justify the decision for our selection of the nine guidance documents reviewed in this literature review in section “ Identifying guidance ”. In brief, these nine guidance documents were selected as the most relevant health care guidance that inform UK systematic reviewing practice, given that the UK occupies a prominent position in the science of health information retrieval. We acknowledge the existence of other guidance documents, such as those from North America (e.g. the Agency for Healthcare Research and Quality (AHRQ) [ 126 ], The Institute of Medicine [ 127 ] and the guidance and resources produced by the Canadian Agency for Drugs and Technologies in Health (CADTH) [ 128 ]). We comment further on this directly below.

The handbooks are potentially linked to one another

What is not clear is the extent to which the guidance documents inter-relate or provide guidance uniquely. The Cochrane Handbook, first published in 1994, is notably a key source of reference in guidance and systematic reviews beyond Cochrane reviews. It is not clear to what extent broadening the sample of guidance handbooks to include North American handbooks, and guidance handbooks from other relevant countries too, would alter the findings of this literature review or develop further support for the process model. Since we cannot be clear, we raise this as a potential limitation of this literature review. On our initial review of a sample of North American, and other, guidance documents (before selecting the guidance documents considered in this review), however, we do not consider that the inclusion of these further handbooks would alter significantly the findings of this literature review.

This is a literature review

A further limitation of this review was that the review of published studies is not a systematic review of the evidence for each key stage. It is possible that other relevant studies could help contribute to the exploration and development of the key stages identified in this review.

This literature review would appear to demonstrate the existence of a shared model of the literature searching process in systematic reviews. We call this model ‘the conventional approach’, since it appears to be common convention in nine different guidance documents.

The findings reported above reveal eight key stages in the process of literature searching for systematic reviews. These key stages are consistently reported in the nine guidance documents which suggests consensus on the key stages of literature searching, and therefore the process of literature searching as a whole, in systematic reviews.

In Table 2 , we demonstrate consensus regarding the application of literature search methods. All guidance documents distinguish between primary and supplementary search methods. Bibliographic database searching is consistently the first method of literature searching referenced in each guidance document. Whilst the guidance uniformly supports the use of supplementary search methods, there is little evidence for a consistent process with diverse guidance across documents. This may reflect differences in the core focus across each document, linked to differences in identifying effectiveness studies or qualitative studies, for instance.

Eight of the nine guidance documents reported on the aims of literature searching. The shared understanding was that literature searching should be thorough and comprehensive in its aim and that this process should be reported transparently so that that it could be reproduced. Whilst only three documents explicitly link this understanding to minimising bias, it is clear that comprehensive literature searching is implicitly linked to ‘not missing relevant studies’ which is approximately the same point.

Defining the key stages in this review helps categorise the scholarship available, and it prioritises areas for development or further study. The supporting studies on preparing for literature searching (key stage three, ‘preparation’) were, for example, comparatively few, and yet this key stage represents a decisive moment in literature searching for systematic reviews. It is where search strategy structure is determined, search terms are chosen or discarded, and the resources to be searched are selected. Information specialists, librarians and researchers, are well placed to develop these and other areas within the key stages we identify.

This review calls for further research to determine the suitability of using the conventional approach. The publication dates of the guidance documents which underpin the conventional approach may raise questions as to whether the process which they each report remains valid for current systematic literature searching. In addition, it may be useful to test whether it is desirable to use the same process model of literature searching for qualitative evidence synthesis as that for reviews of intervention effectiveness, which this literature review demonstrates is presently recommended best practice.

Abbreviations

Behaviour of interest; Health context; Exclusions; Models or Theories

Cochrane Database of Systematic Reviews

The Cochrane Central Register of Controlled Trials

Database of Abstracts of Reviews of Effects

Enhancing transparency in reporting the synthesis of qualitative research

Institute for Quality and Efficiency in Healthcare

National Institute for Clinical Excellence

Population, Intervention, Comparator, Outcome

Preferred Reporting Items for Systematic Reviews and Meta-Analyses

Setting, Perspective, Intervention, Comparison, Evaluation

Sample, Phenomenon of Interest, Design, Evaluation, Research type

STrengthening the Reporting of OBservational studies in Epidemiology

Trial Search Co-ordinators

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Acknowledgements

CC acknowledges the supervision offered by Professor Chris Hyde.

This publication forms a part of CC’s PhD. CC’s PhD was funded through the National Institute for Health Research (NIHR) Health Technology Assessment (HTA) Programme (Project Number 16/54/11). The open access fee for this publication was paid for by Exeter Medical School.

RG and NB were partially supported by the National Institute for Health Research (NIHR) Collaboration for Leadership in Applied Health Research and Care South West Peninsula.

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Cooper, C., Booth, A., Varley-Campbell, J. et al. Defining the process to literature searching in systematic reviews: a literature review of guidance and supporting studies. BMC Med Res Methodol 18 , 85 (2018). https://doi.org/10.1186/s12874-018-0545-3

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A systematic approach to searching: an efficient and complete method to develop literature searches

Associated data.

Creating search strategies for systematic reviews, finding the best balance between sensitivity and specificity, and translating search strategies between databases is challenging. Several methods describe standards for systematic search strategies, but a consistent approach for creating an exhaustive search strategy has not yet been fully described in enough detail to be fully replicable. The authors have established a method that describes step by step the process of developing a systematic search strategy as needed in the systematic review. This method describes how single-line search strategies can be prepared in a text document by typing search syntax (such as field codes, parentheses, and Boolean operators) before copying and pasting search terms (keywords and free-text synonyms) that are found in the thesaurus. To help ensure term completeness, we developed a novel optimization technique that is mainly based on comparing the results retrieved by thesaurus terms with those retrieved by the free-text search words to identify potentially relevant candidate search terms. Macros in Microsoft Word have been developed to convert syntaxes between databases and interfaces almost automatically. This method helps information specialists in developing librarian-mediated searches for systematic reviews as well as medical and health care practitioners who are searching for evidence to answer clinical questions. The described method can be used to create complex and comprehensive search strategies for different databases and interfaces, such as those that are needed when searching for relevant references for systematic reviews, and will assist both information specialists and practitioners when they are searching the biomedical literature.

INTRODUCTION

Librarians and information specialists are often involved in the process of preparing and completing systematic reviews (SRs), where one of their main tasks is to identify relevant references to include in the review [ 1 ]. Although several recommendations for the process of searching have been published [ 2 – 6 ], none describe the development of a systematic search strategy from start to finish.

Traditional methods of SR search strategy development and execution are highly time consuming, reportedly requiring up to 100 hours or more [ 7 , 8 ]. The authors wanted to develop systematic and exhaustive search strategies more efficiently, while preserving the high sensitivity that SR search strategies necessitate. In this article, we describe the method developed at Erasmus University Medical Center (MC) and demonstrate its use through an example search. The efficiency of the search method and outcome of 73 searches that have resulted in published reviews are described in a separate article [ 9 ].

As we aimed to describe the creation of systematic searches in full detail, the method starts at a basic level with the analysis of the research question and the creation of search terms. Readers who are new to SR searching are advised to follow all steps described. More experienced searchers can consider the basic steps to be existing knowledge that will already be part of their normal workflow, although step 4 probably differs from general practice. Experienced searchers will gain the most from reading about the novelties in the method as described in steps 10–13 and comparing the examples given in the supplementary appendix to their own practice.

CREATING A SYSTEMATIC SEARCH STRATEGY

Our methodology for planning and creating a multi-database search strategy consists of the following steps:

• Determine a clear and focused question
• Describe the articles that can answer the question
• Decide which key concepts address the different elements of the question
• Decide which elements should be used for the best results
• Choose an appropriate database and interface to start with
• Document the search process in a text document
• Identify appropriate index terms in the thesaurus of the first database
• Identify synonyms in the thesaurus
• Add variations in search terms
• Use database-appropriate syntax, with parentheses, Boolean operators, and field codes
• Optimize the search
• Evaluate the initial results
• Check for errors
• Translate to other databases
• Test and reiterate

Each step in the process is reflected by an example search described in the supplementary appendix .

1. Determine a clear and focused question

A systematic search can best be applied to a well-defined and precise research or clinical question. Questions that are too broad or too vague cannot be answered easily in a systematic way and will generally result in an overwhelming number of search results. On the other hand, a question that is too specific will result into too few or even zero search results. Various papers describe this process in more detail [ 10 – 12 ].

2. Describe the articles that can answer the question

Although not all clinical or research questions can be answered in the literature, the next step is to presume that the answer can indeed be found in published studies. A good starting point for a search is hypothesizing what the research that can answer the question would look like. These hypothetical (when possible, combined with known) articles can be used as guidance for constructing the search strategy.

3. Decide which key concepts address the different elements of the question

Key concepts are the topics or components that the desired articles should address, such as diseases or conditions, actions, substances, settings, domains (e.g., therapy, diagnosis, etiology), or study types. Key concepts from the research question can be grouped to create elements in the search strategy.

Elements in a search strategy do not necessarily follow the patient, intervention, comparison, outcome (PICO) structure or any other related structure. Using the PICO or another similar framework as guidance can be helpful to consider, especially in the inclusion and exclusion review stage of the SR, but this is not necessary for good search strategy development [ 13 – 15 ]. Sometimes concepts from different parts of the PICO structure can be grouped together into one search element, such as when the desired outcome is frequently described in a certain study type.

4. Decide which elements should be used for the best results

Not all elements of a research question should necessarily be used in the search strategy. Some elements are less important than others or may unnecessarily complicate or restrict a search strategy. Adding an element to a search strategy increases the chance of missing relevant references. Therefore, the number of elements in a search strategy should remain as low as possible to optimize recall.

Using the schema in Figure 1 , elements can be ordered by their specificity and importance to determine the best search approach. Whether an element is more specific or more general can be measured objectively by the number of hits retrieved in a database when searching for a key term representing that element. Depending on the research question, certain elements are more important than others. If articles (hypothetically or known) exist that can answer the question but lack a certain element in their titles, abstracts, or keywords, that element is unimportant to the question. An element can also be unimportant because of expected bias or an overlap with another element.

Schema for determining the optimal order of elements

Bias in elements

The choice of elements in a search strategy can introduce bias through use of overly specific terminology or terms often associated with positive outcomes. For the question “does prolonged breastfeeding improve intelligence outcomes in children?,” searching specifically for the element of duration will introduce bias, as articles that find a positive effect of prolonged breastfeeding will be much more likely to mention time factors in their titles or abstracts.

Overlapping elements

Elements in a question sometimes overlap in their meaning. Sometimes certain therapies are interventions for one specific disease. The Lichtenstein technique, for example, is a repair method for inguinal hernias. There is no need to include an element of “inguinal hernias” to a search for the effectiveness of the Lichtenstein therapy. Likewise, sometimes certain diseases are only found in certain populations. Adding such an overlapping element could lead to missing relevant references.

The elements to use in a search strategy can be found in the plot of elements in Figure 1 , by following the top row from left to right. For this method, we recommend starting with the most important and specific elements. Then, continue with more general and important elements until the number of results is acceptable for screening. Determining how many results are acceptable for screening is often a matter of negotiation with the SR team.

5. Choose an appropriate database and interface to start with

Important factors for choosing databases to use are the coverage and the presence of a thesaurus. For medically oriented searches, the coverage and recall of Embase, which includes the MEDLINE database, are superior to those of MEDLINE [ 16 ]. Each of these two databases has its own thesaurus with its own unique definitions and structure. Because of the complexity of the Embase thesaurus, Emtree, which contains much more specific thesaurus terms than the MEDLINE Medical Subject Headings (MeSH) thesaurus, translation from Emtree to MeSH is easier than the other way around. Therefore, we recommend starting in Embase.

MEDLINE and Embase are available through many different vendors and interfaces. The choice of an interface and primary database is often determined by the searcher’s accessibility. For our method, an interface that allows searching with proximity operators is desirable, and full functionality of the thesaurus, including explosion of narrower terms, is crucial. We recommend developing a personal workflow that always starts with one specific database and interface.

6. Document the search process in a text document

We advise designing and creating the complete search strategies in a log document, instead of directly in the database itself, to register the steps taken and to make searches accountable and reproducible. The developed search strategies can be copied and pasted into the desired databases from the log document. This way, the searcher is in control of the whole process. Any change to the search strategy should be done in the log document, assuring that the search strategy in the log is always the most recent.

7. Identify appropriate index terms in the thesaurus of the first database

Searches should start by identifying appropriate thesaurus terms for the desired elements. The thesaurus of the database is searched for matching index terms for each key concept. We advise restricting the initial terms to the most important and most relevant terms. Later in the process, more general terms can be added in the optimization process, in which the effect on the number of hits, and thus the desirability of adding these terms, can be evaluated more easily.

Several factors can complicate the identification of thesaurus terms. Sometimes, one thesaurus term is found that exactly describes a specific element. In contrast, especially in more general elements, multiple thesaurus terms can be found to describe one element. If no relevant thesaurus terms have been found for an element, free-text terms can be used, and possible thesaurus terms found in the resulting references can be added later (step 11).

Sometimes, no distinct thesaurus term is available for a specific key concept that describes the concept in enough detail. In Emtree, one thesaurus term often combines two or more elements. The easiest solution for combining these terms for a sensitive search is to use such a thesaurus term in all elements where it is relevant. Examples are given in the supplementary appendix .

8. Identify synonyms in the thesaurus

Most thesauri offer a list of synonyms on their term details page (named Synonyms in Emtree and Entry Terms in MeSH). To create a sensitive search strategy for SRs, these terms need to be searched as free-text keywords in the title and abstract fields, in addition to searching their associated thesaurus terms.

The Emtree thesaurus contains more synonyms (300,000) than MeSH does (220,000) [ 17 ]. The difference in number of terms is even higher considering that many synonyms in MeSH are permuted terms (i.e., inversions of phrases using commas).

Thesaurus terms are ordered in a tree structure. When searching for a more general thesaurus term, the more specific (narrower) terms in the branches below that term will also be searched (this is frequently referred to as “exploding” a thesaurus term). However, to perform a sensitive search, all relevant variations of the narrower terms must be searched as free-text keywords in the title or abstract, in addition to relying on the exploded thesaurus term. Thus, all articles that describe a certain narrower topic in their titles and abstracts will already be retrieved before MeSH terms are added.

9. Add variations in search terms (e.g., truncation, spelling differences, abbreviations, opposites)

Truncation allows a searcher to search for words beginning with the same word stem. A search for therap* will, thus, retrieve therapy, therapies, therapeutic, and all other words starting with “therap.” Do not truncate a word stem that is too short. Also, limitations of interfaces should be taken into account, especially in PubMed, where the number of search term variations that can be found by truncation is limited to 600.

Databases contain references to articles using both standard British and American English spellings. Both need to be searched as free-text terms in the title and abstract. Alternatively, many interfaces offer a certain code to replace zero or one characters, allowing a search for “pediatric” or “paediatric” as “p?ediatric.” Table 1 provides a detailed description of the syntax for different interfaces.

Field codes in five most used interfaces for biomedical literature searching

Searching for abbreviations can identify extra, relevant references and retrieve more irrelevant ones. The search can be more focused by combining the abbreviation with an important word that is relevant to its meaning or by using the Boolean “NOT” to exclude frequently observed, clearly irrelevant results. We advise that searchers do not exclude all possible irrelevant meanings, as it is very time consuming to identify all the variations, it will result in unnecessarily complicated search strategies, and it may lead to erroneously narrowing the search and, thereby, reduce recall.

Searching partial abbreviations can be useful for retrieving relevant references. For example, it is very likely that an article would mention osteoarthritis (OA) early in the abstract, replacing all further occurrences of osteoarthritis with OA . Therefore, it may not contain the phrase “hip osteoarthritis” but only “hip oa.”

It is also important to search for the opposites of search terms to avoid bias. When searching for “disease recurrence,” articles about “disease free” may be relevant as well. When the desired outcome is survival , articles about mortality may be relevant.

10. Use database-appropriate syntax, with parentheses, Boolean operators, and field codes

Different interfaces require different syntaxes, the special set of rules and symbols unique to each database that define how a correctly constructed search operates. Common syntax components include the use of parentheses and Boolean operators such as “AND,” “OR,” and “NOT,” which are available in all major interfaces. An overview of different syntaxes for four major interfaces for bibliographic medical databases (PubMed, Ovid, EBSCOhost, Embase.com, and ProQuest) is shown in Table 1 .

Creating the appropriate syntax for each database, in combination with the selected terms as described in steps 7–9, can be challenging. Following the method outlined below simplifies the process:

• Create single-line queries in a text document (not combining multiple record sets), which allows immediate checking of the relevance of retrieved references and efficient optimization.
• Type the syntax (Boolean operators, parentheses, and field codes) before adding terms, which reduces the chance that errors are made in the syntax, especially in the number of parentheses.
• Use predefined proximity structures including parentheses, such as (() ADJ3 ()) in Ovid, that can be reused in the query when necessary.
• Use thesaurus terms separately from free-text terms of each element. Start an element with all thesaurus terms (using “OR”) and follow with the free-text terms. This allows the unique optimization methods as described in step 11.
• When adding terms to an existing search strategy, pay close attention to the position of the cursor. Make sure to place it appropriately either in the thesaurus terms section, in the title/abstract section, or as an addition (broadening) to an existing proximity search.

The supplementary appendix explains the method of building a query in more detail, step by step for different interfaces: PubMed, Ovid, EBSCOhost, Embase.com, and ProQuest. This method results in a basic search strategy designed to retrieve some relevant references upon which a more thorough search strategy can be built with optimization such as described in step 11.

11. Optimize the search

The most important question when performing a systematic search is whether all (or most) potentially relevant articles have been retrieved by the search strategy. This is also the most difficult question to answer, since it is unknown which and how many articles are relevant. It is, therefore, wise first to broaden the initial search strategy, making the search more sensitive, and then check if new relevant articles are found by comparing the set results (i.e., search for Strategy #2 NOT Strategy #1 to see the unique results).

A search strategy should be tested for completeness. Therefore, it is necessary to identify extra, possibly relevant search terms and add them to the test search in an OR relationship with the already used search terms. A good place to start, and a well-known strategy, is scanning the top retrieved articles when sorted by relevance, looking for additional relevant synonyms that could be added to the search strategy.

We have developed a unique optimization method that has not been described before in the literature. This method often adds valuable extra terms to our search strategy and, therefore, extra, relevant references to our search results. Extra synonyms can be found in articles that have been assigned a certain set of thesaurus terms but that lack synonyms in the title and/or abstract that are already present in the current search strategy. Searching for thesaurus terms NOT free-text terms will help identify missed free-text terms in the title or abstract. Searching for free-text terms NOT thesaurus terms will help identify missed thesaurus terms. If this is done repeatedly for each element, leaving the rest of the query unchanged, this method will help add numerous relevant terms to the query. These steps are explained in detail for five different search platforms in the supplementary appendix .

12. Evaluate the initial results

The results should now contain relevant references. If the interface allows relevance ranking, use that in the evaluation. If you know some relevant references that should be included in the research, search for those references specifically; for example, combine a specific (first) author name with a page number and the publication year. Check whether those references are retrieved by the search. If the known relevant references are not retrieved by the search, adapt the search so that they are. If it is unclear which element should be adapted to retrieve a certain article, combine that article with each element separately.

Different outcomes are desired for different types of research questions. For instance, in the case of clinical question answering, the researcher will not be satisfied with many references that contain a lot of irrelevant references. A clinical search should be rather specific and is allowed to miss a relevant reference. In the case of an SR, the researchers do not want to miss any relevant reference and are willing to handle many irrelevant references to do so. The search for references to include in an SR should be very sensitive: no included reference should be missed. A search that is too specific or too sensitive for the intended goal can be adapted to become more sensitive or specific. Steps to increase sensitivity or specificity of a search strategy can be found in the supplementary appendix .

13. Check for errors

Errors might not be easily detected. Sometimes clues can be found in the number of results, either when the number of results is much higher or lower than expected or when many retrieved references are not relevant. However, the number expected is often unknown, and very sensitive search strategies will always retrieve many irrelevant articles. Each query should, therefore, be checked for errors.

One of the most frequently occurring errors is missing the Boolean operator “OR.” When no “OR” is added between two search terms, many interfaces automatically add an “AND,” which unintentionally reduces the number of results and likely misses relevant references. One good strategy to identify missing “OR”s is to go to the web page containing the full search strategy, as translated by the database, and using Ctrl-F search for “AND.” Check whether the occurrences of the “AND” operator are deliberate.

Ideally, search strategies should be checked by other information specialists [ 18 ]. The Peer Review of Electronic Search Strategies (PRESS) checklist offers good guidance for this process [ 4 ]. Apart from the syntax (especially Boolean operators and field codes) of the search strategy, it is wise to have the search terms checked by the clinician or researcher familiar with the topic. At Erasmus MC, researchers and clinicians are involved during the complete process of structuring and optimizing the search strategy. Each word is added after the combined decision of the searcher and the researcher, with the possibility of directly comparing results with and without the new term.

14. Translate to other databases

To retrieve as many relevant references as possible, one has to search multiple databases. Translation of complex and exhaustive queries between different databases can be very time consuming and cumbersome. The single-line search strategy approach detailed above allows quick translations using the find and replace method in Microsoft Word (<Ctrl-H>).

At Erasmus MC, macros based on the find-and-replace method in Microsoft Word have been developed for easy and fast translation between the most used databases for biomedical and health sciences questions. The schema that is followed for the translation between databases is shown in Figure 2 . Most databases simply follow the structure set by the Embase.com search strategy. The translation from Emtree terms to MeSH terms for MEDLINE in Ovid often identifies new terms that need to be added to the Embase.com search strategy before the translation to other databases.

Schematic representation of translation between databases used at Erasmus University Medical Center

Dotted lines represent databases that are used in less than 80% of the searches.

Using five different macros, a thoroughly optimized query in Embase.com can be relatively quickly translated into eight major databases. Basic search strategies will be created to use in many, mostly smaller, databases, because such niche databases often do not have extensive thesauri or advanced syntax options. Also, there is not much need to use extensive syntax because the number of hits and, therefore, the amount of noise in these databases is generally low. In MEDLINE (Ovid), PsycINFO (Ovid), and CINAHL (EBSCOhost), the thesaurus terms must be adapted manually, as each database has its own custom thesaurus. These macros and instructions for their installation, use, and adaptation are available at bit.ly/databasemacros.

15. Test and reiterate

Ideally, exhaustive search strategies should retrieve all references that are covered in a specific database. For SR search strategies, checking searches for their recall is advised. This can be done after included references have been determined by the authors of the systematic review. If additional papers have been identified through other non-database methods (i.e., checking references in included studies), results that were not identified by the database searches should be examined. If these results were available in the databases but not located by the search strategy, the search strategy should be adapted to try to retrieve these results, as they may contain terms that were omitted in the original search strategies. This may enable the identification of additional relevant results.

A methodology for creating exhaustive search strategies has been created that describes all steps of the search process, starting with a question and resulting in thorough search strategies in multiple databases. Many of the steps described are not new, but together, they form a strong method creating high-quality, robust searches in a relatively short time frame.

Our methodology is intended to create thoroughness for literature searches. The optimization method, as described in step 11, will identify missed synonyms or thesaurus terms, unlike any other method that largely depends on predetermined keywords and synonyms. Using this method results in a much quicker search process, compared to traditional methods, especially because of the easier translation between databases and interfaces (step 13). The method is not a guarantee for speed, since speed depends on many factors, including experience. However, by following the steps and using the tools as described above, searchers can gain confidence first and increase speed through practice.

What is new?

This method encourages searchers to start their search development process using empty syntax first and later adding the thesaurus terms and free-text synonyms. We feel this helps the searcher to focus on the search terms, instead of on the structure of the search query. The optimization method in which new terms are found in the already retrieved articles is used in some other institutes as well but has to our knowledge not been described in the literature. The macros to translate search strategies between interfaces are unique in this method.

What is different compared to common practice?

Traditionally, librarians and information specialists have focused on creating complex, multi-line (also called line-by-line) search strategies, consisting of multiple record sets, and this method is frequently advised in the literature and handbooks [ 2 , 19 – 21 ]. Our method, instead, uses single-line searches, which is critical to its success. Single-line search strategies can be easily adapted by adding or dropping a term without having to recode numbers of record sets, which would be necessary in multi-line searches. They can easily be saved in a text document and repeated by copying and pasting for search updates. Single-line search strategies also allow easy translation to other syntaxes using find-and-replace technology to update field codes and other syntax elements or using macros (step 13).

When constructing a search strategy, the searcher might experience that certain parentheses in the syntax are unnecessary, such as parentheses around all search terms in the title/abstract portion, if there is only one such term, there are double parentheses in the proximity statement, or one of the word groups exists for only one word. One might be tempted to omit those parentheses for ease of reading and management. However, during the optimization process, the searcher is likely to find extra synonyms that might consist of one word. To add those terms to the first query (with reduced parentheses) requires adding extra parentheses (meticulously placing and counting them), whereas, in the latter search, it only requires proper placement of those terms.

Many search methods highly depend on the PICO framework. Research states that often PICO or PICOS is not suitable for every question [ 22 , 23 ]. There are other acronyms than PICO—such as sample, phenomenon of interest, design, evaluation, research type (SPIDER) [ 24 ]—but each is just a variant. In our method, the most important and specific elements of a question are being analyzed for building the best search strategy.

Though it is generally recommended that searchers search both MEDLINE and Embase, most use MEDLINE as the starting point. It is considered the gold standard for biomedical searching, partially due to historical reasons, since it was the first of its kind, and more so now that it is freely available via the PubMed interface. Our method can be used with any database as a starting point, but we use Embase instead of MEDLINE or another database for a number of reasons. First, Embase provides both unique content and the complete content of MEDLINE. Therefore, searching Embase will be, by definition, more complete than searching MEDLINE only. Second, the number of terms in Emtree (the Embase thesaurus) is three times as high as that of MeSH (the MEDLINE thesaurus). It is easier to find MeSH terms after all relevant Emtree terms have been identified than to start with MeSH and translate to Emtree.

At Erasmus MC, the researchers sit next to the information specialist during most of the search strategy design process. This way, the researchers can deliver immediate feedback on the relevance of proposed search terms and retrieved references. The search team then combines knowledge about databases with knowledge about the research topic, which is an important condition to create the highest quality searches.

Limitations of the method

One disadvantage of single-line searches compared to multi-line search strategies is that errors are harder to recognize. However, with the methods for optimization as described (step 11), errors are recognized easily because missed synonyms and spelling errors will be identified during the process. Also problematic is that more parentheses are needed, making it more difficult for the searcher and others to assess the logic of the search strategy. However, as parentheses and field codes are typed before the search terms are added (step 10), errors in parentheses can be prevented.

Our methodology works best if used in an interface that allows proximity searching. It is recommended that searchers with access to an interface with proximity searching capabilities select one of those as the initial database to develop and optimize the search strategy. Because the PubMed interface does not allow proximity searches, phrases or Boolean “AND” combinations are required. Phrase searching complicates the process and is more specific, with the higher risk of missing relevant articles, and using Boolean “AND” combinations increases sensitivity but at an often high loss of specificity. Due to some searchers’ lack of access to expensive databases or interfaces, the freely available PubMed interface may be necessary to use, though it should never be the sole database used for an SR [ 2 , 16 , 25 ]. A limitation of our method is that it works best with subscription-based and licensed resources.

Another limitation is the customization of the macros to a specific institution’s resources. The macros for the translation between different database interfaces only work between the interfaces as described. To mitigate this, we recommend using the find-and-replace functionality of text editors like Microsoft Word to ease the translation of syntaxes between other databases. Depending on one’s institutional resources, custom macros can be developed using similar methods.

Results of the method

Whether this method results in exhaustive searches where no important article is missed is difficult to determine, because the number of relevant articles is unknown for any topic. A comparison of several parameters of 73 published reviews that were based on a search developed with this method to 258 reviews that acknowledged information specialists from other Dutch academic hospitals shows that the performance of the searches following our method is comparable to those performed in other institutes but that the time needed to develop the search strategies was much shorter than the time reported for the other reviews [ 9 ].

CONCLUSIONS

With the described method, searchers can gain confidence in their search strategies by finding many relevant words and creating exhaustive search strategies quickly. The approach can be used when performing SR searches or for other purposes such as answering clinical questions, with different expectations of the search’s precision and recall. This method, with practice, provides a stepwise approach that facilitates the search strategy development process from question clarification to final iteration and beyond.

SUPPLEMENTAL FILE

Acknowledgments.

We highly appreciate the work that was done by our former colleague Louis Volkers, who in his twenty years as an information specialist in Erasmus MC laid the basis for our method. We thank Professor Oscar Franco for reviewing earlier drafts of this article.

A systematic exploration of scoping and mapping literature reviews

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• Published: 23 May 2024

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• Eirini Christou   ORCID: orcid.org/0000-0001-6928-1013 1 ,
• Antigoni Parmaxi   ORCID: orcid.org/0000-0002-0687-0176 1 &
• Panayiotis Zaphiris   ORCID: orcid.org/0000-0001-8112-5099 1  

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Systematic literature mapping can help researchers identify gaps in the research and provide a comprehensive overview of the available evidence. Despite the importance and benefits of conducting systematic scoping and mapping reviews, many researchers may not be familiar with the methods and best practices for conducting these types of reviews. This paper aims to address this gap by providing a step-by-step guide to conducting a systematic scoping or mapping review, drawing on examples from different fields. This study adopts a systematic literature review approach aiming to identify and present the steps of conducting scoping and mapping literature reviews and serves as a guide on conducting scoping or mapping systematic literature reviews. A number of 90 studies were included in this study. The findings describe the steps to follow when conducting scoping and mapping reviews and suggest the integration of the card sorting method as part of the process. The proposed steps for undertaking scoping and mapping reviews presented in this manuscript, highlight the importance of following a rigorous approach for conducting scoping or mapping reviews.

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1 Introduction

An essential component of academic research is literature review. A systematic literature review, also known as a systematic review, is a method for locating, assessing, and interpreting all research related to a specific research question, topic, or phenomenon of interest [ 1 ].

Scoping and mapping reviews are variations of systematic literature mapping [ 2 ]. Both mapping and scoping reviews can help researchers to understand the scope and breadth of the literature in a given field, identify gaps in the research, and provide a comprehensive overview of the available evidence. Systematic literature mapping purposely focuses on a narrower but more general academic or policy issue and does not try to synthesize the results of research to address a particular subject. The scoping review is exploratory in nature, whereas the mapping review can be conclusive in describing the available evidence and identifying gaps. Mapping review includes a thorough, systematic search of a wide field. It identifies the body of literature that is currently available on a subject and points out any glaring gaps in the evidence [ 3 ].

1.1 Rationale

Despite the importance and benefits of conducting systematic scoping and mapping reviews, many researchers may not be familiar with the methods and best practices for conducting these types of reviews. This paper aims to address this gap by providing a step-by-step guide to conducting a systematic scoping or mapping review, drawing on examples from different fields.

This study adopts a systematic literature review approach aiming to identify and present the differences and the steps of conducting scoping and mapping literature review. The paper provides practical guidance on how to address common challenges in conducting systematic scoping or mapping reviews, such as dealing with the volume of studies identified, managing the data extraction and synthesis process, and ensuring rigor and reproducibility in the review methodology. The main research questions that guide this study are:

RQ1: What is a systematic scoping review and how is it conducted?

RQ2: What is a systematic mapping review and how is it conducted?

RQ3: What are the main differences between systematic scoping and systematic mapping reviews?

Overall, this paper will be a valuable resource for researchers who are interested in conducting a systematic scoping or mapping review. By providing clear guidance and practical examples, the paper aims to promote best practices in systematic scoping and mapping review methodology. The study is organized as follows: The following section presents the methodology of the study, followed by the results showing the process of the scoping and mapping literature review and presenting some examples. Finally, suggestions on how to plan and perform a quality scoping and mapping review are presented.

2 Methodology

The methodology of this paper was adopted by Xiao and Watson [ 4 ].

2.1 Literature search

The search was conducted in two well-known online databases, Web of Science and EBSCOHost, across various disciplines. The searched terms combined keywords related to the performance of scoping and mapping literature review, such as “systematic literature review”, “methodology”, “map”, “mapping” and “scoping”. The title of each manuscript was used to determine its initial relevance. If the content of the title suggested that it would explain the method of the literature review process, we obtained the full reference, which included the author, year, title, and abstract, for additional analysis.

2.2 Initial search results

The query string used for the database search is the following: systematic literature review AND methodology AND (“map” OR “mapping” OR “scoping”). Abstract search was conducted in both databases for the last 10 years (2013–2022). A search on EBSCOHost revealed 643 results of which 291 were duplicated and automatically removed. After applying the database filters to limit the articles to peer-reviewed academic journal articles written in English, a number of 102 papers were excluded. Additional 109 papers were duplicated and removed manually. After an initial screening of the titles, a total of 13 studies were identified as relevant to the methodology of the scoping and mapping literature review. A search on Web of Science, revealed 888 results of which 9 were duplicate and removed, and 157 were found to be related to the methodology of scoping or mapping literature reviews after the first title screening. Last search was conducted on the 2nd of November 2022. Both sources revealed 161 related studies, excluding 9 duplicates that were removed.

2.3 Inclusion and exclusion criteria

Only studies that provide instructions on how to perform a scoping or mapping review were included in this paper. Reviews of the literature on certain subjects and in languages other than English were excluded. The study is limited to papers published within the last 10 years, aiming to collect recent information for performing scoping or mapping reviews. Inclusion and exclusion criteria can be found in Table  1 .

2.4 Screening

To further assess the 161 studies’ applicability to the study topic, their abstracts were reviewed. The manuscripts were evaluated independently and in parallel by two researchers. The researchers’ differing opinions were discussed and settled. Then the full-text of a total of 20 studies was acquired for quality evaluation.

2.5 Eligibility and quality evaluation

To further assess the quality and relevance of the studies, the full-text papers were reviewed. Journal articles and books published by prominent publishers were included in the review as they contained high-quality research. Because there is no peer review procedure, the majority of technical reports and online presentations were excluded.

Two researchers worked independently and simultaneously on evaluating eligibility and quality. Any disagreements between them were discussed and resolved. A total of ten (10) studies were excluded after careful review: one study was excluded because it lacked instructions on how the scoping or mapping review methodology was conducted, three studies were excluded because the methodology was not related to scoping or mapping review, while five studies were disregarded because they focused on a particular subject. One of the studies’ full text couldn’t be accessed. This resulted in ten (10) eligible for full-text analysis.

2.6 Iterations

Through backward and forward searching, additional 18 studies were discovered, from which only 10 met the inclusion criteria. The forward and backward search was also used to find manuscripts that applied scoping or mapping literature review methodology. After finding the article that established the scoping or mapping review methodology, articles that had cited the methodology paper to find instances of best practices in different fields were searched. Following consideration of examples’ adherence to the methodology, preference was given to planning-related articles. In total, 90 studies were analyzed in this study, i.e. 10 methodological papers that describe the application of scoping or mapping review, as well as 80 papers that demonstrate the application of the scoping and mapping methodology in different fields, that are used as examples. The PRISMA flow diagram (see Fig.  1 ) depicts the process of the search strategy [ 5 ].

PRISMA flow diagram

2.7 Extraction and analysis of data

Data were extracted in the process of scoping literature reviews, including information with regards to formulating the problem, establishing and validating the review procedure, searching the literature, screening for inclusion, evaluating quality, extracting data, analyzing and synthesizing data, and reporting the findings (Xiao & Watson, 2019). NVivo software was used for all data extraction and coding procedures. Initially, two researchers each took information from articles for cross-checking. The two researchers reached an agreement on what to extract from the publications after reviewing a few articles together. Then the first author classified the data based on the research questions.

In this section we present the findings of our review.

3.1 Defining “Scoping” and “mapping” review

According to [ 2 ], scoping and mapping reviews are variations of systematic literature mapping that focus on narrower but more general academic or policy issues. A scoping review is exploratory in nature, seeking to identify the nature and extent of research on a particular topic, and can be used to identify gaps in the literature. An example of a research question suitable for a scoping review is “What engagement strategies do educators use in classroom settings to facilitate teaching and learning of diverse students in undergraduate nursing programs?“ [ 6 ]. A mapping review, on the other hand, is a thorough and systematic search of a wide field of literature that aims to identify the body of literature currently available on a subject and point out any glaring gaps in the evidence. An example of a research question suitable for a mapping review is “What are the currently available animal models for cystic fibrosis” [ 3 ]. Overall, each type of review has its own specific aims and can be useful for different types of research questions.

3.1.1 Defining scoping review

There is no single definition for scoping reviews in the literature. According to [ 7 ], scoping review is a type of knowledge synthesis that uses a systematic process to map the evidence on a subject and identify key ideas, theories, sources, and knowledge gaps. The goal of a scoping review is to include all relevant information that is available, including ‘grey’ literature, which includes unpublished research findings, therefore including all available literature and evidence, but the reviewers can decide what type of publications they would like to include [ 8 , 9 , 10 , 11 ].

Scoping review process is sometimes used as a preliminary step before a systematic literature review, in cases where the topic or research area in focus has not yet been extensively reviewed or is complicated or heterogeneous in nature and the types of evidence available remain unclear [ 3 ]. For example, while a scoping review might serve as the foundation for a full systematic review, it does not aim to evaluate the quality of the evidence like systematic reviews do [ 8 ]. Moreover, scoping review is also referred to as a “pilot study” [ 12 ], that can be used as a “trial run” of the entire systematic map; it helps to mold the intended approach for the review and inform the protocol development.

Rapid and scoping meta-reviews were also referred as types of scoping reviews. A “rapid review” is a particular kind of scoping review, which aims to provide an answer to a particular query and can shorten the process compared to a full systematic review [ 3 ]. The “scoping meta-review” (SMR) is a scoping evaluation of systematic reviews that offers researchers a flexible framework for field mapping and a way to condense pertinent research activities and findings, similar to a scoping review [ 13 ].

Almost all of the scoping studies identified in the corpus, draw from previews scoping review frameworks, such as the one proposed by [ 14 , 15 ] and the authors’ manual provided by the Joanna Briggs Institute [ 11 , 16 , 17 , 18 ].

3.1.2 Defining mapping review

A mapping review, also referred to as a “systematic map”, is “a high-level review with a broad research question” [ 3 ](p.133). The mapping review includes a thorough, systematic search of a wide field. It identifies the body of literature that is currently available on a subject and points out any gaps in the evidence. The mapping review can be conclusive in describing the available evidence and identifying gaps, whereas the scoping review is exploratory in nature [ 3 ].

The term “mapping” is used to describe the process of synthesizing and representing the literature numerically and thematically in tables, figures, or graphical representations, which can be thought of as the review output. Mapping enables researchers to pinpoint potential areas for further study as well as gaps in the literature [ 19 ].

Systematic mapping uses the same strict procedures as systematic reviews do. However, systematic mapping can be used to address open or closed-framed questions on broad or specific topics, because it is not constrained by the requirement to include fully specified and defined key elements [ 12 ]. Systematic mapping is especially useful for broad, multifaceted questions about an interesting topic that might not be appropriate for systematic review because they involve a variety of interventions, populations, or outcomes, or because they draw on evidence that is not just from primary research [ 12 ].

3.2 Process of conducting mapping and scoping reviews

As noted in the previous sections, mapping reviews and scoping reviews both aim to provide a broad overview of the literature, but the former focuses on the scope of the literature while the latter focuses on the nature and extent of available evidence on a specific research question or topic. In understanding the process for conducting mapping and scoping reviews, we adopted the eight steps proposed by Xiao and Watson [ 4 ] that are common for all types of reviews: (1) Formulate the problem; (2) Establishing and validating the review procedure; (3) Searching the literature; (4) Screening for inclusion; (5) Evaluating quality; (6) Extracting data; (7) Analyzing and synthesizing data; (8) Reporting the findings. The steps are explained in detail below and describe the methodology for both scoping and mapping reviews, distinguishing their differences where applicable. A summary of the review types along with their characteristics and steps as identified from the literature are presented in Table  2 .

3.2.1 Step 1 formulate the problem

The first step for undertaking a mapping or a scoping review is to formulate the problem by setting the research question that should be investigated, taking into account the topic’s scope [ 12 ]. It is important to clearly state the review objectives and specific review questions for the scoping review. The objectives should indicate what the scoping review is trying to achieve [ 10 , 20 ].

In mapping reviews, it can be helpful to create a conceptual framework or model (visual or textual) to describe what will be explored by the map when determining the mapping review’s scope. It should also be determined whether the topic’s scope is broad, specific, or likely to be supported by a substantial body of evidence [ 12 ].

3.2.1.1 Defining the research question(s)

Prior to beginning their search and paper selection process, the authors should typically define their research question(s) [ 3 ]. There are specific formats that are recommended for structuring the research question(s), as well as the exclusion and inclusion criteria of mapping and scoping reviews [ 21 ] (see Table  3 ).

PCC (Population, Concept, and Context) and PICO format (Population, Intervention, Comparator and Outcome) are often used in scoping and mapping reviews. It is recommended that research questions for scoping reviews follow the PCC format and include all of its components [ 17 , 18 , 21 ]. Information about the participants (e.g. age), the principal idea or “concept,” and the setting of the review, should all be included in the research question. The context should be made explicit and may take into account geographical or locational considerations, cultural considerations, and particular racial or gender-based concerns [ 10 ].

Researchers use the PCC format in order to determine the eligibility of their research questions, as well as to define their inclusion criteria (e.g [ 22 , 23 , 24 , 25 , 26 ]). Most scoping reviews have a single main question, but some of them are better served by one or more sub-questions that focus on specific PCC characteristics [ 8 , 18 ].

3.2.2 Step 2. Establishing and validating the review procedure

A protocol is crucial for scoping and mapping reviews because it pre-defines the scoping review’s goals and procedures [ 11 , 17 , 18 , 20 ], it clearly states all methodological decisions since the very beginning [ 2 ], and it also specifies the strategy to be used at each stage of the review process [ 12 ]. Similar to all systematic reviews, scoping reviews start with the creation of an a-priori protocol that includes inclusion and exclusion criteria that are directly related to the review’s objectives and questions [ 7 , 11 , 17 , 18 , 20 ]. In order to decrease study duplication and improve data reporting transparency, the use of formalized, registered protocols is suggested [ 18 , 19 ]. The international prospective register of systematic reviews, known as PROSPERO, states that scoping reviews (and literature reviews) are currently ineligible for registration in the database. While this could change in the future, scoping reviews can currently be registered with the Open Science Framework ( https://osf.io/ ) or Figshare ( https://figshare.com/ ), and their protocols can be published in select publications, including the JBI Evidence Synthesis [ 18 ].

Scoping and mapping reviews should require at least two reviewers in order to minimize reporting bias, as well as to ensure consistency and clarity [ 3 , 16 , 17 , 18 ]. The reviewers should include a plan for the results presentation during the protocol development, such as a draft chart or table that could be improved at the end when the reviewers become more familiar with the information they have included in the review [ 17 , 18 ].

3.2.3 Step 3. Searching the literature

Searching the literature requires to prepare a search strategy, decide on search terms, search databases or journals, and perform a manual search [ 27 ]. For example, deciding on search terms, can follow an iterative process that is further explained in the sub-section below. Thinking about searching in terms of broader to narrower strategies is helpful. Fewer databases and/or journals will be checked out in narrower searches (search only in the title, keywords, and abstract fields), which are frequently used in scoping reviews, while multiple databases can be checked for mapping reviews [ 2 ].

Search strategy

Mapping and scoping review search should aim to be as thorough as possible [ 12 ] to find both published and unpublished evidence. An inclusive approach is frequently preferred for scoping reviews to prevent potential omission of crucial information [ 10 , 17 , 18 ].

According to JBI, there should be a three-step search process for scoping reviews [ 10 , 17 , 18 ]. The first step is a quick search of at least two databases followed by a text word check of the article’s title, abstract, and body of text that are then analyzed. All determined index terms and keywords are used in the second stage across all included databases. In the third stage, additional studies should be looked up in the identified reports and articles’ reference lists [ 10 , 11 , 18 ]. The reviewers may look solely at the reference lists of the studies that were chosen from the full-text and/or included in the review, or they may look at the reference lists of all identified studies. In any case, it needs to be made very clear which group of studies will be looked at [ 8 , 11 , 18 ]. As reviewers gain more familiarity with the body of available evidence, new keywords, sources, and possibly helpful search terms may be found and incorporated into the search strategy, hence the search for a scoping review may be quite iterative. If so, it is crucial that the entire search process and the outcomes are open to scrutiny and audit [ 11 , 18 ].

In the same line, it is recommended for mapping reviews to search multiple databases [ 2 ] in all pertinent searchable fields (e.g., title, abstract, keywords, etc.) [ 3 ]. Thematic keywords, along with all of their synonyms and regional/temporal variations, are joined together to form Boolean strings using Boolean signs. Building looser, multiple Boolean strings instead of well-targeted ones (for example, using OR instead of AND, NOT, and exact phrases, respectively) is preferable. The latter runs the risk of omitting crucial references, whereas the former may return a sizable sample of sparsely relevant references [ 2 ]. Focusing the search on a specific component and then filtering all the results can be more effective for mapping reviews [ 3 ].

3.2.4 Step 4. Screening for inclusion

Screening and choosing the studies to be included in a review are the main objectives of this phase. According to [ 27 ], there are two levels of screening. Titles and abstracts are scanned in the first level to limit the range of the studies to be included, while full texts are scanned in the second level to re-examine the relevance of the studies and to settle disagreements between reviewers regarding the study selection. Discussions, meetings, consulting a third reviewer, and determining inter-rater reliability/agreement (using Cohen’s kappa coefficient or intraclass correlation coefficient) are the most typical ways to resolve disagreements. Soaita et al. (2020) [ 2 ] also support that the sample of retrieved references should be ‘cleaned-up’ once it has been finalized and duplicates have been automatically removed.

Different methodological approaches, including primary research articles, summary articles, opinion pieces, and grey literature, can all be included in the literature that scoping reviews identify and analyze [ 7 , 18 , 19 ], but they may also serve as an exclusion criterion [ 2 ]. Peters, Godfrey, et al. (2020) [ 18 ] advice against limiting source inclusion based on language unless there are compelling justifications for doing so (such as practical considerations).

According to the PRISMA extension for scoping reviews (PRISMA-ScR), a description of the study selection process must be provided in both a narrative and flow diagram format. Including the date of the most recent literature search, enables the reader to assess how current the scoping review is [ 7 ].

3.2.4.1 Inclusion and exclusion criteria

Inclusion criteria offer a framework on which the reviewers can decide which sources to include in the scoping review. To ensure transparency and replicability, the exclusion and inclusion criteria need to be documented [ 7 , 8 , 10 , 11 , 17 ]. Authors should specify any limitations by year, language, publication status, or other factors, and explain why each one was put in place [ 7 ].

When it comes to mapping reviews, criteria should be created whenever possible with participation from stakeholders. Depending on the type of research questions, stakeholders may include practitioners, designers, policy makers, scientists and research funding bodies, but attention should be paid to avoid bias [ 12 ].

3.2.5 Step 5. Evaluating quality

Scoping and mapping reviews are not concerned with quality assessment as a criterion for inclusion [ 2 ]. Assessments of reporting quality and bias risk are typically outside the scope. Although it is possible to extract study characteristics that reflect study and reporting quality, bias cannot be assessed against a specific hypothesis if a mapping review is exploratory [ 3 ].

3.2.6 Step 6. Extracting data

The process of data extraction for a scoping review is also known as “charting the results”. A draft charting table or form needs to be created to capture the key details about the relevance of the included studies to the review question, as well as the characteristics of the included studies. The data extraction process can be iterative, with the charting table being constantly updated.

The reviewers should become familiar with the source results and test the extraction form on two or three studies to ensure that all relevant results are extracted [ 7 , 8 , 10 , 11 , 17 , 18 , 28 ]. In order to increase reporting transparency, authors should explain the main revisions with a justification if the charting process was iterative (i.e., the form was continuously updated). If appropriate, details about the procedures used to collect and verify information from the researchers of the included sources of evidence should be provided [ 7 ]. Author(s), year of publication, source origin, country of origin, objectives, purpose, study population, sample size, methodology, intervention type and comparator, concept, duration of the intervention, how outcomes are measured, and key findings that are related to the review question are all types of information that may be extracted [ 7 , 8 , 10 , 11 , 17 ].

When it comes to data extraction for mapping reviews, it is restricted to important study characteristics and outcomes due to the size of a mapping review [ 3 ]. The process of mapping is intended to produce a practical and organized resource that provides enough detail about studies to be helpful in further work [ 12 ].

To move beyond a straightforward list of citations, it is crucial to maintain a high level of clarity throughout any databases that are created. Studies that are discussed in several papers or that seem to be connected should be marked in the database. In the future, this helps prevent the double counting of research findings in syntheses that might overlook connections between study lines in the databases [ 12 ].

Aiming to capture the key characteristics of the included studies in the scoping and mapping reviews, we suggest the use of a guiding table for extracting data (see Supplementary_Material_1_Guiding_Table).

3.2.7 Step 7. Analyzing and synthesizing data

Authors may extract results and map descriptively. Simple frequency counts of concepts, populations, characteristics, or other fields of data will suffice for many scoping reviews [ 17 , 18 ]. In-depth analysis of quantitative data is not typically required in scoping reviews, although in some cases the authors may take into consideration a more advanced analysis depending on the nature and purpose of their review. A meta-analysis or interpretive qualitative analysis is probably not necessary in scoping reviews [ 17 , 18 ].

When it comes to mapping reviews, no results synthesis is carried out [ 12 ]. Different analytical approaches can be used to map chronological, geographical, conceptual, and thematic trends, which include some form of coding, once the sample has been limited to the pertinent references [ 2 ]. It is possible to identify correlations, trends, gaps, and clusters using simple numerical accounts of frequencies in each category (for example, the number of studies looking at a specific species) and more complex cross-tabulations (for instance, the number of studies looking at the effectiveness of a specific intervention, in a particular farming system, for a named species). Users have access to the map and can query it to find information pertaining to any chosen combinations of the subsets of the meta-data [ 12 ].

3.2.8 Step 8. Reporting the findings

Authors should specify exactly how the evidence will be presented, whether it be in a narrative format, table, or visual representation, such as a map or diagram [ 7 ].

In scoping reviews, a summary of all the relevant information gathered can be presented [ 8 ] using a logical and descriptive summary of the findings based on the research questions [ 10 , 11 , 17 ]. The distribution of studies by year or period of publication, countries of origin, field of intervention, and research methodologies, may be displayed in the tables and charts accompanied with a narrative summary that explains how the results relate to the review’s objectives [ 7 , 11 , 17 , 18 ].

The conclusions should be consistent with the review objective or question based on the findings of the scoping review [ 10 ]. Following the conclusions, specific recommendations for future research based on gaps in knowledge identified by the review results can be presented. Because of the lack of a methodological quality appraisal, recommendations for practice may be unable to be developed; however, suggestions based on the conclusions may be made [ 10 ].

A scoping review’s results section should include a PRISMA flow diagram and details the outcomes of the search strategy and selection procedure [ 7 , 17 ] outlining the grounds for exclusion at the full-text level of screening [ 7 ]. For example, a study [ 29 ] used the PRISMA-ScR extension for scoping reviews to ensure all important sections have been covered in their review.

Mapping reviews may place more emphasis on describing the evidence. The use of pivot tables and pivot charts is helpful for quickly visualizing the amount (and quality, if it is measured) of evidence across a variety of meta-data variables [ 12 ]. Such visualizations can display the quantity of research, the conclusions of a critical appraisal, the sample size across nations, outcomes, populations, or variables. These visualizations can contain categorical variables as additional dimensions. The geographic distribution of study effort and type may be particularly important in mapping reviews with a global or large-scale reach [ 12 ].

4 Discussion

This systematic literature review aimed to describe the process of conducting mapping and scoping literature reviews. In summary, the main difference between the two types of reviews is in their focus and scope. Mapping reviews provide a comprehensive overview of the literature while scoping reviews identify gaps and inconsistencies in the literature and outline potential areas for future research.

A lot of the methodological papers included in this systematic literature review (e.g [ 10 , 19 , 28 ]), referred to the “consultation process” as an additional, optional step that has been suggested by [ 14 ]. In this stage, subject experts or potential review users like practitioners, consumers, and policymakers may be consulted [ 8 ]. Researchers argue that this step should be mandatory [ 15 , 28 ]. In agreement with Levac et al.’s [ 15 ] choice, Daudt et al. [ 28 ] encourage the use of the consultation stage whenever it is practical because it adds richness to the entire research process and, consequently, the findings. Despite the fact that stakeholder consultations can make scoping review planning and execution more difficult, they guarantee that the findings are pertinent to educational practice and/or policies [ 19 ].

Scoping and mapping reviews should require more than one author to eliminate bias and ensure their quality. The card-sorting technique is suggested to be employed within the review process as a means for resolving discrepancies between the stakeholders and come to an agreement on the categorization and evaluation of the data to be included. Other studies (e.g [ 30 , 31 , 32 , 33 ]), propose the card-sorting technique as a method for resolving disagreements between people’s disparities, as well as to evaluate and verify extracted themes from datasets. Card sorting is a quick and reliable sorting method that finds patterns in how users would expect to find content or functionality. Due to the patterns and insights it exposes about how people organize and categorize content, card sorting is a successful approach for resolving categorization disagreements [ 34 ]. According to Wood and Wood [ 35 ], the majority of card sorting projects involve an open sort, where participants receive a list of items and are asked to organize them in the most appropriate way. However, in some cases, a pre-existing set of categories is given to the participants, the so-called closed card sorting project. This assumes that the existing categories are already well-organized, and the goal is to make minor adjustments. Wood and Wood [ 35 ], suggest that it’s best to start with an open sort and analyze the data before conducting a closed sort for validation. If a closed sort is necessary, it should be kept simple, and the results may not be optimal. For example, in a study [ 30 ] that aimed to review the use of makerspaces for educational purposes, the card sorting technique was used for the development of the coding scheme. A three-member academic committee, consisting of three professors took part in the card sorting exercise where they went through the abstracts of the relevant papers and were asked to categorize each manuscript after discussion. They then categorized the manuscripts in the three major themes and 11 subcategories that emerged during the card sorting exercise [ 30 ]. Similarly, the authors of [ 31 ] employed the card sorting technique in their research in order to agree on the main categorization and sub-categorization of the articles identified for inclusion in their review. Card sorting can be integrated as an additional step when conducting scoping and mapping reviews, as it provides useful insights from the experts’ perspective and makes the mapping process more inclusive (see Fig.  2 ).

Proposed steps for conducting scoping and mapping reviews

5 Conclusion

Scoping and mapping reviews need a methodological framework that is rigorous, consistent, and transparent, so that the results can be trusted and the review replicated. This provides enough information for the readers to evaluate the review’s accuracy, relevance, and thoroughness [ 8 ]. Scoping reviews should be carried out in accordance with established methodological guidance and reported using reporting standards (like PRISMA-ScR) guidelines [ 36 ]. The proposed steps for undertaking scoping and mapping reviews presented in this manuscript, highlight the importance of following a rigorous approach for conducting scoping or mapping reviews. Overall, this paper is a valuable resource for researchers who are interested in conducting a systematic scoping or mapping review in different fields and are looking to apply these review methods to their own research questions.

5.1 Limitations and future work

This study does not lack limitations. As specific keywords and specific databases were searched, not all relevant work is included. The study was also limited to the past 10 years, letting out methodologies and frameworks for scoping and mapping literature reviews that were not published within the specific timeframe. The fact that the number of methodological papers identified for inclusion are limited to ten, makes it difficult to clarify the differences between mapping and scoping reviews. Therefore, further research is encouraged in order to clarify and verify the differences and similarities between the two. The application of the proposed process for conducting systematic scoping and mapping reviews on specific topics will verify the process.

Data availability

The data that support the findings of this study are available from the corresponding author, [EC], upon reasonable request.

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Christou, E., Parmaxi, A. & Zaphiris, P. A systematic exploration of scoping and mapping literature reviews. Univ Access Inf Soc (2024). https://doi.org/10.1007/s10209-024-01120-3

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Barriers and facilitators to mental health treatment access and engagement for LGBTQA+ people with psychosis: a scoping review protocol

• Cláudia C. Gonçalves   ORCID: orcid.org/0000-0001-6767-0920 1 ,
• Zoe Waters 2 ,
• Shae E. Quirk 1 ,
• Peter M. Haddad 1 , 3 ,
• Ashleigh Lin 4 ,
• Lana J. Williams 1 &
• Alison R. Yung 1 , 5  

Systematic Reviews volume  13 , Article number:  143 ( 2024 ) Cite this article

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The prevalence of psychosis has been shown to be disproportionately high amongst sexual and gender minority individuals. However, there is currently little consideration of the unique needs of this population in mental health treatment, with LGBTQA+ individuals facing barriers in accessing timely and non-stigmatising support for psychotic experiences. This issue deserves attention as delays to help-seeking and poor engagement with treatment predict worsened clinical and functional outcomes for people with psychosis. The present protocol describes the methodology for a scoping review which will aim to identify barriers and facilitators faced by LGBTQA+ individuals across the psychosis spectrum in help-seeking and accessing mental health support.

A comprehensive search strategy will be used to search Medline, PsycINFO, Embase, Scopus, LGBTQ+ Source, and grey literature. Original studies of any design, setting, and publication date will be included if they discuss barriers and facilitators to mental health treatment access and engagement for LGBTQA+ people with experiences of psychosis. Two reviewers will independently screen titles/abstracts and full-text articles for inclusion in the review. Both reviewers will then extract the relevant data according to pre-determined criteria, and study quality will be assessed using the Joanna Briggs Institute (JBI) critical appraisal checklists. Key data from included studies will be synthesised in narrative form according to the Guidance on the Conduct of Narrative Synthesis in Systematic Reviews.

The results of this review will provide a comprehensive account of the current and historical barriers and facilitators to mental healthcare faced by LGBTQA+ people with psychotic symptoms and experiences. It is anticipated that the findings from this review will be relevant to clinical and community services and inform future research. Findings will be disseminated through publication in a peer-reviewed journal and presented at conferences.

Scoping review registration

This protocol is registered in Open Science Framework Registries ( https://doi.org/10.17605/OSF.IO/AT6FC ).

Peer Review reports

The prevalence of psychotic disorders in the general population has been estimated to be around 0.27–0.75% [ 1 , 2 ], with the lifetime prevalence of ever having a psychotic experience being estimated at 5.8% [ 3 ]. However, rates of psychotic symptoms and experiences are disproportionately high amongst LGBTQA+ populations, with non-heterosexual individuals estimated to be 1.99–3.75 times more likely to experience psychosis than their heterosexual peers [ 4 , 5 , 6 , 7 ]. Additionally, it has been estimated that transgender or gender non-conforming (henceforth trans) individuals are 2.46–49.7 times more likely than their cisgender peers (i.e. individuals whose gender identity is the same as their birth registered sex) to receive a psychotic disorder diagnosis [ 8 , 9 ]. The increased rates of psychotic experiences noted amongst gender and sexual minorities may be explained by evidence indicating that LGBTQA+ people are also exposed to risk factors for psychosis at a far greater rate than members of the general population, such as childhood adversity [ 10 , 11 , 12 ], minority stress [ 13 ], discrimination [ 14 ], and stigma [ 15 , 16 ]. Furthermore, there is added potential for diagnostic biases leading to over-diagnosing psychosis in gender diverse individuals, whose gender expression and dysphoria may be pathologized by mental health service providers [ 8 ].

Despite these concerning statistics, there is very little research examining the experiences of LGBTQA+ people with psychosis, and limited consideration of the unique needs these individuals may have in accessing and engaging with mental health services. While timely access to treatment has consistently been associated with better symptomatic and functional outcomes for people with psychosis [ 17 , 18 ], there are often delays to treatment initiation which are worsened for LGBTQA+ individuals [ 19 , 20 ]. These individuals face additional barriers to accessing adequate mental health support compared to cisgender/heterosexual people [ 19 ] and may need to experiment with several mental health services before finding culturally competent care [ 20 ]. This in turn may lead to longer duration of untreated psychosis. Additionally, there seems to be a lack of targeted support for this population from healthcare providers, with LGBTQA+ individuals with serious mental health concerns reporting higher rates of dissatisfaction with psychiatric services than their cisgender and heterosexual counterparts [ 7 , 14 , 21 ]. However, the extent of these differences varies across contexts [ 22 ], potentially due to improved education around stigma and LGBTQA+ issues within a subset of mental health services.

Nonetheless, stigma remains one of the highest cited barriers to help-seeking for mental health problems, particularly with regard to concerns around disclosure [ 23 ], which can be particularly challenging for people experiencing psychosis [ 24 , 25 ]. Stigma stress in young people at risk for psychosis is associated with less positive attitudes towards help-seeking regarding both psychiatric medication and psychotherapy [ 26 ], potentially partly due to fears of judgement and being treated differently by service providers [ 27 ]. This issue may be compounded for people who also belong to minoritized groups [ 23 , 28 ], particularly as LGBTQA+ individuals have reported experiencing frequent stigma and encountering uninformed staff when accessing mental healthcare [ 7 , 29 ]. Furthermore, stigma-fuelled hesitance to access services may be heightened for trans people [ 30 ] whose identities have historically been pathologized and conflated with experiences of psychosis [ 31 ].

Even when individuals manage to overcome barriers to access support, there are added challenges to maintaining adequate treatment engagement. In a large online study, half of trans and nearly one third of LGB participants reported having stopped using mental health services in the past because of negative experiences related to their gender identity or sexuality [ 20 ]. This can be particularly problematic as experiences of stigma predict poorer medication adherence in psychosis [ 32 ] which subsequently multiplies the risk for relapse and suicide [ 33 ]. While no research to date has explored non-adherence rates in people with psychosis who are LGBTQA+, concerns around suicidality are heightened for individuals who are gender and sexuality diverse [ 34 , 35 , 36 ].

Generally, there is rising demand for mental healthcare that specifically addresses the needs of gender and sexual minority individuals and promotes respect for diversity, equity, and inclusion [ 29 , 37 ]. This is particularly salient as positive relationships with staff are associated with better medication adherence for people with psychosis [ 38 ] and healthcare providers with LGBTQA+-specific mandates have demonstrated higher satisfaction rates for LGBTQA+ individuals [ 20 ]. Mental health services need to adapt treatment options to acknowledge minority stress factors for those with stigmatised identities and, perhaps more importantly, how these intersect and interact to increase inequalities in people from minoritized groups accessing and benefiting from treatment [ 37 , 39 ].

Additionally, gender affirming care needs to be recognised as an important facet of mental health treatment for many trans individuals, as it is associated with positive outcomes such as improvements in quality of life and psychological functioning [ 40 , 41 , 42 ] and reductions in psychiatric symptom severity and need for subsequent mental health treatment [ 8 , 43 ]. While there are additional barriers in access to gender affirming care for individuals with psychosis, this treatment has shown success in parallel with treatment to address psychosis symptom stabilisation [ 19 , 44 ]. The importance of affirmation is echoed by the finding that many negative experiences of LGBTQA+ participants with mental health services could be avoided simply by respecting people’s pronouns and using gender-neutral language [ 20 ].

To ensure timely access to appropriate treatment for LGBTQA+ people with psychosis, there is a need for improved understanding of the factors which challenge and facilitate help-seeking and engagement with mental health support. A preliminary search of Google Scholar, Medline, the Cochrane Database of Systematic Reviews, and PROSPERO was conducted and revealed no existing or planned reviews exploring benefits and/or obstacles to mental health treatment specific to this population. Therefore, the proposed review seeks to comprehensively search and appraise the existing literature to identify and summarise a range of barriers and facilitators to adequate mental health support faced by LGBTQA+ people with experiences of psychosis. This will allow for the mapping of the types of evidence available and identification of any knowledge gaps. Moreover, we hope to guide future decision-making in mental healthcare to improve service accessibility for LGBTQA+ individuals with psychosis and to set the foundations for future research that centres this marginalised population. Based on published guidance [ 45 , 46 , 47 ], a scoping review methodology was identified as the most appropriate approach to address these aims.

Selection criteria

This scoping review protocol has been developed in compliance with the JBI Manual for Evidence Synthesis [ 48 ] and, where relevant, the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) checklist [ 49 ] (see Additional file 1). In the event of protocol amendments, the date, justification, and description for each amendment will be provided.

Due to the limited literature around the topic of this review, any primary original study design, setting, and publication date will be considered for inclusion. Publications written in English will be included, and articles in other languages may be considered pending time and cost constraints around translation. Publications will be excluded if the full text is not available upon request from authors.

The PCC (Population, Concept, Context) framework was used to develop the inclusion criteria for this scoping review:

This review will include individuals of any age who are LGBTQA+ and have had experiences of psychosis. For the purposes of this review, ‘LGBTQA+ individuals’ will be broadly defined as any individual that is not heterosexual and/or cisgender or anyone who engages in same-gender sexual behaviour. Studies may include participants who are cisgender and heterosexual if they separately report outcomes for LGBTQA+ individuals. Within this review, the term ‘psychosis’ includes (i) any diagnosis of a psychotic disorder, such as schizophrenia spectrum disorders, mood disorders with psychotic features, delusional disorders, and drug-induced psychotic disorders, (ii) sub-threshold psychotic symptoms, such as those present in ultra-high risk (UHR), clinical high risk (CHR), or at risk mental state (ARMS) individuals, and (iii) any psychotic-like symptoms or experiences. Studies may include participants with multiple diagnoses if they separately report outcomes for individuals on the psychosis spectrum.

This review will include publications which discuss potential barriers and/or facilitators to mental health help-seeking and/or engagement with mental health treatment. ‘Barriers’ will be operationalised as any factors which may delay or prevent individuals from accessing and engaging with appropriate mental health support. These may include lack of mental health education, experienced or internalised stigma, experiences of discrimination from health services, and lack of inclusivity in health services. ‘Facilitators’ will be operationalised as any factors which may promote timely help-seeking and engagement with sources of support. These may include improved access to mental health education, positive sources of social support, and welcoming and inclusive services. Mental health help-seeking will be broadly defined as any attempt to seek and access formal or informal support to address a mental health concern related to experiences of psychosis (e.g. making an initial appointment with a service provider, seeking help from a friend). Mental health treatment engagement will be broadly defined as adherence and active participation in the treatment that is offered by a source of support (e.g. attending scheduled appointments, taking medication as prescribed, openly communicating with service providers).

This review may include research encompassing any setting in which mental healthcare is provided. This is likely to include formal healthcare settings such as community mental health teams or inpatient clinics as well as informal settings such as LGBTQA+ spaces or informal peer support. Studies will be excluded if they focus exclusively on physical health treatment.

Search strategy

Database searches will be conducted in Medline, PsycINFO, Embase, Scopus, and LGBTQ+ Source. The full search strategy for this protocol is available (see Additional file 2). This strategy has been collaboratively developed and evaluated by a scholarly services health librarian. Searches will include subject headings relevant to each database and title/abstract keywords relating to three main concepts: (i) LGBTQA+ identity, (ii) experiences of psychosis, and (iii) mental health treatment. Keywords for each concept will be combined using the Boolean operator ‘OR’, and the three concepts will be combined using ‘AND’. This search strategy was appropriately translated for each of the selected databases. There will be no limitations on language or publication date at this stage to maximise the breadth of the literature captured. Publications returned from these searches will be exported to EndNote. Searches will be re-run prior to the final analysis to capture any newly published studies.

The database searches will be supplemented by searching the grey literature as per the eligibility criteria detailed above. These may include theses and dissertations, conference proceedings, reports from mental health services, and policy documents from LGBTQA+ groups. Google and Google Scholar will be searched using a combination of clauses for psychosis (Psychosis OR psychotic OR schizophrenia OR schizoaffective), treatment (treatment or “help-seeking”), and queer identity. The latter concept will have three clauses for three separate searches, with one including broad queer identity (LGBT), one specific to non-heterosexual individuals (gay OR lesbian OR homosexual OR bisexual OR queer OR asexual), and one specific to trans individuals (transgender OR transsexual OR transexual OR “non-binary” OR “gender minority”). Additionally, reference lists and citing literature will be manually searched for each paper included in the review to capture any articles and policy documents not previously identified.

Data selection

Search results will be imported into Covidence using EndNote, and duplicates will be eliminated. Titles and abstracts will be screened by the first and second authors according to pre-defined screening criteria, which will be discussed by the authors and piloted prior to screening. These criteria will consider whether the articles included LGBTQA+ participants with experiences of psychosis (as operationalised above) in relation to mental health help-seeking and/or treatment. Full texts of relevant articles will then be obtained and screened by the first and second reviewer in accordance with the full inclusion and exclusion criteria after initial piloting to maximise inter-rater reliability. Decisions on inclusion and exclusion will be blinded and recorded on Covidence. Potential discrepancies will be resolved through discussion, and when consensus cannot be reached, these will be resolved by the supervising author. The process of study selection will be documented using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram [ 50 ].

Data extraction

Data extraction will be performed independently by two reviewers using Covidence. Prior to beginning final extraction, both reviewers will independently pilot the extraction tool using a sample of five included studies and discuss any necessary changes. Information extracted is planned to include the following: title, author name(s), year of publication, country in which the study was conducted, study design, sample size, population of focus (i.e. sexual minorities, gender minorities, or both), sample demographics (i.e. age, gender identity, and sexual orientation), setting (e.g. early intervention service, community mental health team, etc.), psychosis characteristics (e.g. diagnoses included, severity of symptoms, etc.), type of treatment (e.g. cognitive behavioural therapy, antipsychotic medication, etc.), and any barriers and/or facilitators identified according to the aforementioned operationalised definitions. Disagreements will be resolved through discussion between the two reviewers and, when necessary, final decisions will be made by a senior supervisor. Once extracted, information will be recorded in Excel. Lead authors of papers will be contacted by the primary review author in cases where there is missing or insufficient data.

Quality assessment

Due to the expected heterogeneity in the types of studies that may be included in this review (e.g. qualitative studies, randomised controlled trials, case control studies, case reports), the relevant revised Joanna Briggs Institute (JBI) critical appraisal checklists [ 51 ] will be used to assess risk of bias and study quality for each study design. Two reviewers will independently use these checklists to assess each paper that is included following the full-text screening. If there are discrepancies in article ratings, these will be resolved through discussion between the two authors. If no consensus is reached, discrepancies will be resolved by a senior supervisor. In line with the scoping nature of this review, low-quality studies will not be excluded from the synthesis.

Evidence synthesis

Data from included studies will be synthesised using a narrative synthesis approach in accordance with the Guidance on the Conduct of Narrative Synthesis in Systematic Reviews [ 52 ]. A preliminary descriptive synthesis will be conducted by tabulating the extracted data elements from each study alongside quality assessment results and developing an initial description of the barriers and facilitators to (1) accessing and (2) engaging with mental health support that are identified in the literature. This initial synthesis will then be interrogated and refined to contextualise these barriers and facilitators in the setting, population, and methodology of each study to form the basis for an interpretative synthesis.

This review will not use a pre-existing thematic framework to categorise barriers and facilitators as it is expected that the factors identified will not neatly fit into existing criteria. Instead, these will be conceptualised according to overarching themes as interrelated factors, so that potentially complex interactions between barriers and facilitators within and across relevant studies may be explored through concept mapping. If most of the studies included are qualitative, there may also be scope for a partial meta-synthesis. To avoid oversimplifying the concept of ‘barriers and facilitators’ (see criticism by Bach-Mortensen & Verboom [ 53 ]), this data synthesis will be followed by a critical reflection of the findings through the lens of the socio-political contexts which may give rise to the barriers and facilitators identified, exploring the complexities necessary for any changes to be implemented in mental health services.

If the extracted data indicate that gender minority and sexual minority individuals experience unique or different barriers and/or facilitators to each other, these population groups will be analysed separately as opposed to findings being generalised across the LGBTQA+ spectrum. Furthermore, if there is scope to do so, analyses may be conducted to investigate how perceived barriers and facilitators for this population may have changed over time (i.e. according to publication date) as definitions of psychosis evolve and LGBTQA+ individuals gain visibility in clinical services.

The proposed review will add to the literature around mental health treatment for LGBTQA+ people with psychosis. It will provide a thorough account of the barriers and facilitators to accessing and engaging with support faced by this population and may inform future research and clinical practice.

In terms of limitations, this review will be constrained by the existing literature and may therefore not be sufficiently comprehensive in reflecting the barriers and facilitators experienced by subgroups within the broader LGBTQA+ community. Additionally, although broad inclusion criteria are necessary to capture the full breadth of research conducted in this topic, included studies are likely to be heterogeneous and varied in terms of their methodology and population which may complicate data synthesis.

Nonetheless, it is anticipated that the findings from this review will provide the most comprehensive synthesis to date of the issues driving low help-seeking and treatment engagement in people across the psychosis spectrum who are LGBTQA+. This review will likely also identify gaps in the literature which may inform avenues for future research, and the factors identified in this review will be considered in subsequent research by the authors.

Additionally, findings will be relevant to healthcare providers that offer support to people with psychosis who may have intersecting LGBTQA+ identities as well as LGBTQA+ organisations which offer support to LGBTQA+ people who may be experiencing distressing psychotic experiences. These services are likely to benefit from an increased awareness of the factors which may improve or hinder accessibility for these subsets of their target populations. Therefore, results from this review may inform decision-making around the implementation of service-wide policy changes.

The findings of this review will be disseminated through the publication of an article in a peer-reviewed journal and presented at relevant conferences in Australia and/or internationally. Additionally, the completed review will form part of the lead author’s doctoral thesis.

Availability of data and materials

Not applicable for this protocol.

Abbreviations

• At risk mental state

Clinical high risk for psychosis

Joanna Briggs Institute

Lesbian, gay, and bisexual

Lesbian, gay, bisexual, transgender, queer or questioning, asexual or aromantic, and more

Population, Concept, Context

Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols

Ultra-high risk for psychosis

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Acknowledgements

The authors would like to acknowledge the support of Ms Olivia Larobina, Scholarly Services Librarian (STEMM) at Deakin University, in the development of the search strategy.

CCG is funded by a Deakin University Postgraduate Research (DUPR) Scholarship. ZW is funded by a University of Western Australia Research Training Program (RTP) Scholarship. AL is supported by a National Health and Medical Research Council (NHMRC) Emerging Leaders Fellowship (2010063). LJW is supported by a NHMRC Emerging Leaders Fellowship (1174060). ARY is supported by a NHMRC Principal Research Fellowship (1136829). The funding providers had no role in the design and conduct of the study, or in the preparation, review, or approval of this manuscript.

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Cláudia C. Gonçalves, Shae E. Quirk, Peter M. Haddad, Lana J. Williams & Alison R. Yung

Telethon Kids Institute, University of Western Australia, Perth, WA, 6009, Australia

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CCG is the guarantor. CCG conceptualised the review, developed the study design, and drafted the manuscript. CCG, ZW, and SQ collaborated with OL (Scholarly Services Librarian) to develop the search strategy. All authors critically reviewed the manuscript. All authors read and approved the final manuscript.

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Additional file 1. prisma-p 2015 checklist. completed prisma-p checklist for this systematic review protocol., 13643_2024_2566_moesm2_esm.docx.

Additional file 2. Search Strategy. Detailed search strategy for this systematic review, including search terms and relevant controlled vocabulary terms for each included database.

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Gonçalves, C.C., Waters, Z., Quirk, S.E. et al. Barriers and facilitators to mental health treatment access and engagement for LGBTQA+ people with psychosis: a scoping review protocol. Syst Rev 13 , 143 (2024). https://doi.org/10.1186/s13643-024-02566-5

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• Treatment access
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Systematic Reviews

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• Subject guides
• Researching for your literature review
• Develop a search strategy

Researching for your literature review: Develop a search strategy

• Literature reviews
• Literature sources
• Before you start
• Keyword search activity
• Subject search activity
• Combined keyword and subject searching
• Online tutorials
• Apply search limits
• Run a search in different databases
• Supplementary searching
• Save your searches
• Manage results

Identify key terms and concepts

Start developing a search strategy by identifying the key words and concepts within your research question. The aim is to identify the words likely to have been used in the published literature on this topic.

For example: What are the key infection control strategies for preventing the transmission of Meticillin-resistant Staphylococcus aureus (MRSA) in aged care homes .

Treat each component as a separate concept so that your topic is organised into separate blocks (concepts).

For each concept block, list the key words derived from your research question, as well as any other relevant terms or synonyms that you have found in your preliminary searches. Also consider singular and plural forms of words, variant spellings, acronyms and relevant index terms (subject headings).  

As part of the process of developing a search strategy, it is recommended that you keep a master list of search terms for each key concept. This will make it easier when it comes to translating your search strategy across multiple database platforms. 

Concept map template for documenting search terms

Combine search terms and concepts

Boolean operators are used to combine the different concepts in your topic to form a search strategy. The main operators used to connect your terms are AND and OR . See an explanation below:

• Link keywords related to a single concept with OR
• Linking with OR broadens a search (increases the number of results) by searching for any of the alternative keywords

Example: nursing home OR aged care home

• Link different concepts with AND
• Linking with AND narrows a search (reduces the number of results) by retrieving only those records that include all of your specified keywords

Example: nursing home AND infection control

• using NOT narrows a search by excluding results that contain certain search terms
• Most searches do not require the use of the NOT operator

Example: aged care homes NOT residential homes will retrieve all the results that include the words aged care homes but don't include the words residential homes . So if an article discussed both concepts this article would not be retrieved as it would be excluded on the basis of the words residential homes .

See the website for venn diagrams demonstrating the function of AND/OR/NOT:

Combine the search terms using Boolean

Advanced search operators - truncation and wildcards

By using a truncation symbol you can capture all of the various endings possible for a particular word. This may increase the number of results and reduce the likelihood of missing something relevant. Some tips about truncation:

• The truncation symbol is generally an asterisk symbol * and is added at the end of a word.
• It may be added to the root of a word that is a word in itself. Example: prevent * will retrieve prevent, prevent ing , prevent ion prevent ative etc. It may also be added to the root of a word that is not a word in itself. Example: strateg * will retrieve strateg y , strateg ies , strateg ic , strateg ize etc.
• If you don't want to retrieve all possible variations, an easy alternative is to utilise the OR operator instead e.g. strategy OR strategies. Always use OR instead of truncation where the root word is too small e.g. ill OR illness instead of ill*

There are also wildcard symbols that function like truncation but are often used in the middle of a word to replace zero, one or more characters.

• Unlike the truncator which is usually an asterisk, wildcards vary across database platforms
• Common wildcards symbols are the question mark ? and hash #.
• Example:  wom # n finds woman or women, p ? ediatric finds pediatric or paediatric.  

See the Database search tips for details of these operators, or check the Help link in any database.

Phrase searching

For words that you want to keep as a phrase, place two or more words in "inverted commas" or "quote marks". This will ensure word order is maintained and that you only retrieve results that have those words appearing together.

Example: “nursing homes”

There are a few databases that don't require the use of quote marks such as Ovid Medline and other databases in the Ovid suite. The Database search tips provides details on phrase searching in key databases, or you can check the Help link in any database.

Subject headings (index terms)

Identify appropriate subject headings (index terms).

Many databases use subject headings to index content. These are selected from a controlled list and describe what the article is about. 

A comprehensive search strategy is often best achieved by using a combination of keywords and subject headings where possible.

In-depth knowledge of subject headings is not required for users to benefit from improved search performance using them in their searches.

Advantages of subject searching:

• Helps locate articles that use synonyms, variant spellings, plurals
• Search terms don’t have to appear in the title or abstract

Note: Subject headings are often unique to a particular database, so you will need to look for appropriate subject headings in each database you intend to use.

Subject headings are not available for every topic, and it is best to only select them if they relate closely to your area of interest.

MeSH (Medical Subject Headings)

The MeSH thesaurus provides standard terminology, imposing uniformity and consistency on the indexing of biomedical literature. In Pubmed/Medline each record is tagged with  MeSH  (Medical Subject Headings).

The MeSH vocabulary includes:

• Represent concepts found in the biomedical literature
• Some headings are commonly considered for every article (eg. Species (including humans), Sex, Age groups (for humans), Historical time periods)
• attached to MeSH headings to describe a specific aspect of a concept
• describe the type of publication being indexed; i.e., what the item is, not what the article is about (eg. Letter, Review, Randomized Controlled Trial)
• Terms in a separate thesaurus, primarily substance terms

Create a 'gold set'

It is useful to build a ‘sample set’ or ‘gold set’ of relevant references before you develop your search strategy..

Sources for a 'gold set' may include:

• key papers recommended by subject experts or supervisors
• citation searching - looking at a reference list to see who has been cited, or using a citation database (eg. Scopus, Web of Science) to see who has cited a known relevant article
• results of preliminary scoping searches.

The papers in your 'gold set' can then be used to help you identify relevant search terms

• Look up your 'gold set' articles in a database that you will use for your literature review. For the articles indexed in the database, look at the records to see what keywords and/or subject headings are listed.

The 'gold set' will also provide a means of testing your search strategy

• When an article in the sample set that is also indexed in the database is not retrieved, your search strategy can be revised in order to include it (see what concepts or keywords can be incorporated into your search strategy so that the article is retrieved).
• If your search strategy is retrieving a lot of irrelevant results, look at the irrelevant records to determine why they are being retrieved. What keywords or subject headings are causing them to appear? Can you change these without losing any relevant articles from your results?
• Information on the process of testing your search strategy using a gold set can be found in the systematic review guide

Example search strategy

A search strategy is the planned and structured organisation of terms used to search a database.

An example of a search strategy incorporating all three concepts, that could be applied to different databases is shown below:

You will use a combination of search operators to construct a search strategy, so it’s important to keep your concepts grouped together correctly. This can be done with parentheses (round brackets), or by searching for each concept separately or on a separate line.

The above search strategy in a nested format (combined into a single line using parentheses) would look like:

("infection control*" OR "infection prevention") AND ("methicillin resistant staphylococcus aureus" OR "meticillin resistant staphylococcus aureus" OR MRSA) AND ( "aged care home*" OR "nursing home*")

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• Systematic Review
• Open access
• Published: 30 May 2024

Patient experiences: a qualitative systematic review of chemotherapy adherence

• Amineh Rashidi 1 ,
• Susma Thapa 1 ,
• Wasana Sandamali Kahawaththa Palliya Guruge 1 &
• Shubhpreet Kaur 1  

BMC Cancer volume  24 , Article number:  658 ( 2024 ) Cite this article

Metrics details

Adherence to chemotherapy treatment is recognized as a crucial health concern, especially in managing cancer patients. Chemotherapy presents challenges for patients, as it can lead to potential side effects that may adversely affect their mobility and overall function. Patients may sometimes neglect to communicate these side effects to health professionals, which can impact treatment management and leave their unresolved needs unaddressed. However, there is limited understanding of how patients’ experiences contribute to improving adherence to chemotherapy treatment and the provision of appropriate support. Therefore, gaining insights into patients’ experiences is crucial for enhancing the accompaniment and support provided during chemotherapy.

This review synthesizes qualitative literature on chemotherapy adherence within the context of patients’ experiences. Data were collected from Medline, Web of Science, CINAHL, PsychINFO, Embase, Scopus, and the Cochrane Library, systematically searched from 2006 to 2023. Keywords and MeSH terms were utilized to identify relevant research published in English. Thirteen articles were included in this review. Five key themes were synthesized from the findings, including positive outlook, receiving support, side effects, concerns about efficacy, and unmet information needs. The review underscores the importance for healthcare providers, particularly nurses, to focus on providing comprehensive information about chemotherapy treatment to patients. Adopting recommended strategies may assist patients in clinical practice settings in enhancing adherence to chemotherapy treatment and improving health outcomes for individuals living with cancer.

Peer Review reports

Introduction

Cancer can affect anyone and is recognized as a chronic disease characterized by abnormal cell multiplication in the body [ 1 ]. While cancer is prevalent worldwide, approximately 70% of cancer-related deaths occur in low- to middle-income nations [ 1 ]. Disparities in cancer outcomes are primarily attributed to variations in the accessibility of comprehensive diagnosis and treatment among countries [ 1 , 2 ]. Cancer treatment comes in various forms; however, chemotherapy is the most widely used approach [ 3 ]. Patients undergoing chemotherapy experience both disease-related and treatment-related adverse effects, significantly impacting their quality of life [ 4 ]. Despite these challenges, many cancer patients adhere to treatment in the hope of survival [ 5 ]. However, some studies have shown that concerns about treatment efficacy may hinder treatment adherence [ 6 ]. Adherence is defined as “the extent to which a person’s behaviour aligns with the recommendations of healthcare providers“ [ 7 ]. Additionally, treatment adherence is influenced by the information provided by healthcare professionals following a cancer diagnosis [ 8 ]. Patient experiences suggest that the decision to adhere to treatment is often influenced by personal factors, with family support playing a crucial role [ 8 ]. Furthermore, providing adequate information about chemotherapy, including its benefits and consequences, can help individuals living with cancer gain a better understanding of the advantages associated with adhering to chemotherapy treatment [ 9 ].

Recognizing the importance of adhering to chemotherapy treatment and understanding the impact of individual experiences of chemotherapy adherence would aid in identifying determinants of adherence and non-adherence that are modifiable through effective interventions [ 10 ]. Recently, systematic reviews have focused on experiences and adherence in breast cancer [ 11 ], self-management of chemotherapy in cancer patients [ 12 ], and the influence of medication side effects on adherence [ 13 ]. However, these reviews were narrow in scope, and to date, no review has integrated the findings of qualitative studies designed to explore both positive and negative experiences regarding chemotherapy treatment adherence. This review aims to synthesize the qualitative literature on chemotherapy adherence within the context of patients’ experiences.

This review was conducted in accordance with the Joanna Briggs Institute [ 14 ] guidelines for systemic review involving meta-aggregation. This review was registered in PROSPERO (CRD42021270459).

Search methods

The searches for peer reviewed publications in English from January 2006-September 2023 were conducted by using keywords, medical subject headings (MeSH) terms and Boolean operators ‘AND’ and ‘OR’, which are presented in the table in Appendix 1 . The searches were performed in a systematic manner in core databases such including Embase, Medline, PsycINFO, CINAHL, Web of Science, Cochrane Library, Scopus and the Joanna Briggs Institute (JBI). The search strategy was developed from keywords and medical subject headings (MeSH) terms. Librarian’s support and advice were sought in forming of the search strategies.

Study selection and inclusion criteria

The systematic search was conducted on each database and all articles were exported to Endnote and duplicates records were removed. Then, title and abstract of the full text was screened by two independent reviewers against the inclusion criteria. For this review, populations were patients aged 18 and over with cancer, the phenomenon of interest was experiences on chemotherapy adherence and context was considered as hospitals, communities, rehabilitation centres, outpatient clinics, and residential aged care. All peer-reviewed qualitative study design were also considered for inclusion. Studies included in this review were classified as primary research, published in English since 2006, some intervention implemented to improve adherence to treatment. This review excluded any studies that related to with cancer and mental health condition, animal studies and grey literature.

Quality appraisal and data extraction

The JBI Qualitative Assessment and Review Instrument for qualitative studies was used to assess the methodological quality of the included studies, which was conducted by the primary and second reviewers independently. There was no disagreement between the reviews. The qualitative data on objectives, study population, context, study methods, and the phenomena of interest and findings form the included studies were extracted.

Data synthesis

The meta-aggregation approach was used to combine the results with similar meaning. The primary and secondary reviewers created categories based on the meanings and concept. These categories were supported by direct quotations from participants. The findings were assess based on three levels of evidence, including unequivocal, credible, and unsupported [ 15 , 16 ]. Findings with no quotation were not considered for synthesis in this review. The categories and findings were also discussed by the third and fourth reviewers until a consensus was reached. The review was approved by the Edith Cowan University Human Research Ethics Committee (2021–02896).

Study inclusion

A total of 4145 records were identified through a systematic search. Duplicates ( n  = 647) were excluded. Two independent reviewers conducted screening process. The remaining articles ( n  = 3498) were examined for title and abstract screening. Then, the full text screening conducted, yielded 13 articles to be included in the final synthesis see Appendix 2 .

Methodological quality of included studies

All included qualitative studies scored between 7 and 9, which is displayed in Appendix 3 . The congruity between the research methodology and the research question or objectives, followed by applying appropriate data collection and data analysis were observed in all included studies. Only one study [ 17 ] indicated the researcher’s statement regarding cultural or theoretical perspectives. Three studies [ 18 , 19 , 20 ] identified the influence of the researcher on the research and vice-versa.

Characteristics of included studies

Most of studies conducted semi-structured and in-depth interviews, one study used narrative stories [ 19 ], one study used focus group discussion [ 21 ], and one study combined focus group and interview [ 22 ] to collect data. All studies conducted outpatient’s clinic, community, or hospital settings [ 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ]. The study characteristics presented in Appendix 4 .

Review findings

Eighteen findings were extracted and synthesised into five categories: positive outlook, support, side effects, concern about efficacy and unmet information needs.

Positive outlook

Five studies discussed the link between positivity and hope and chemotherapy adherence [ 19 , 20 , 23 , 27 , 28 ]. Five studies commented that feeling positive and avoid the negativity and worry could encourage people to adhere in their mindset chemotherapy: “ I think the main thing for me was just keeping a positive attitude and not worrying, not letting myself worry about it ” [ 20 ]. Participants also considered the positive thoughts as a coping mechanism, that would help them to adhere and complete chemotherapy: “ I’m just real positive on how everything is going. I’m confident in the chemo, and I’m hoping to get out of her soon ” [ 23 ]. Viewing chemotherapy as part of their treatment regimen and having awareness of negative consequences of non-adherence to chemotherapy encouraged them to adhere chemotherapy: “ If I do not take medicine, I do not think I will be able to live ” [ 28 ]. Adhering chemotherapy was described as a survivor tool which helped people to control cancer-related symptoms: “ it is what is going to restore me. If it wasn’t this treatment, maybe I wasn’t here talking to you. So, I have to focus in what he is going to give me, life !” [ 27 ]. Similarly, people accepted the medical facts and prevent their life from worsening; “ without the treatment, it goes the wrong way. It is hard, but I have accepted it from the beginning, yes. This is how it is. I cannot do anything about it. Just have to accept it ” [ 19 ].

Finding from six studies contributed to this category [ 20 , 21 , 23 , 24 , 25 , 29 ]. Providing support from families and friends most important to the people. Receiving support from family members enhanced a sense responsibility towards their families, as they believed to survive for their family even if suffered: “ yes, I just thought that if something comes back again and I say no, then I have to look my family and friends in the eye and say I could have prevented it, perhaps. Now, if something comes back again, I can say I did everything I could. Cancer is bad enough without someone saying: It’s your own fault!!” [ 29 ]. Also, emotional support from family was described as important in helping and meeting their needs, and through facilitation helped people to adhere chemotherapy: “ people who genuinely mean the support that they’re giving […] just the pure joy on my daughter’s face for helping me. she was there day and night for me if I needed it, and that I think is the main thing not to have someone begrudgingly looking after you ” [ 20 ]. Another study discussed the role family, friends and social media as the best source of support during their treatment to adhere and continue “ I have tons of friends on Facebook, believe it or not, and it’s amazing how many people are supportive in that way, you know, just sending get-well wishes. I can’t imagine going through this like 10 years ago whenever stuff like that wasn’t around ” [ 23 ]. Receiving support from social workers was particularly helpful during chemotherapy in encouraging adherence to the chemotherapy: “ the social worker told me that love is courage. That was a huge encouragement, and I began to encourage myself ” [ 25 ].

Side effects

Findings from five studies informed this category [ 17 , 21 , 22 , 25 , 26 ]. Physical side effects were described by some as the most unpleasure experience: “ the side effects were very uncomfortable. I felt pain, fatigue, nausea, and dizziness that limited my daily activities. Sometimes, I was thinking about not keeping to my chemotherapy schedule due to those side effect ” [ 17 ]. The impact of side effects affected peoples’ ability to maintain their independence and self-care: “ I couldn’t walk because I didn’t have the energy, but I wouldn’t have dared to go out because the diarrhoea was so bad. Sometimes I couldn’t even get to the toilet; that’s very embarrassing because you feel like you’re a baby ” [ 26 ]. Some perceived that this resulted in being unable to perform independently: “ I was incredibly weak and then you still have to do things and you can’t manage it ” [ 22 ]. These side effect also decreased their quality of life “ I felt nauseated whenever I smelled food. I simply had no appetite when food was placed in front of me. I lost my sense of taste. Food had no taste anymore ” [ 25 ]. Although, the side effects impacted on patients´ leisure and free-time activities, they continued to undertake treatment: “ I had to give up doing the things I liked the most, such as going for walks or going to the beach. Routines, daily life in general were affected ” [ 21 ].

Concern about efficacy

Findings form four studies informed this category [ 17 , 18 , 24 , 28 ]. Although being concerned about the efficacy of the chemotherapy and whether or not chemotherapy treatment would be successful, one participant who undertook treatment described: “the efficacy is not so great. It is said to expect about 10% improvement, but I assume that it declines over time ” [ 28 ]. People were worried that such treatment could not cure their cancer and that their body suffered more due to the disease: “ I was really worried about my treatment effectiveness, and I will die shortly ” [ 17 ]. There were doubts expressed about remaining the cancer in the body after chemotherapy: “ there’s always sort of hidden worries in there that whilst they’re not actually taking the tumour away, then you’re wondering whether it’s getting bigger or what’s happening to it, whether it’s spreading or whatever, you know ” [ 24 ]. Uncertainty around the outcome of such treatment, or whether recovering from cancer or not was described as: “it makes you feel confused. You don’t know whether you are going to get better or else whether the illness is going to drag along further” [ 18 ].

Unmet information needs

Five studies contributed to this category [ 17 , 21 , 22 , 23 , 26 ]. The need for adequate information to assimilate information and provide more clarity when discussing complex information were described. Providing information from clinicians was described as minimal: “they explain everything to you and show you the statistics, then you’re supposed to take it all on-board. You could probably go a little bit slower with the different kinds of chemo and grappling with these statistics” [ 26 ]. People also used the internet search to gain information about their cancer or treatments, “I’ve done it (consult google), but I stopped right away because there’s so much information and you don’t know whether it’s true or not ” [ 21 ]. The need to receive from their clinicians to obtain clearer information was described as” I look a lot of stuff up online because it is not explained to me by the team here at the hospital ” [ 23 ]. Feeling overwhelmed with the volume of information could inhibit people to gain a better understanding of chemotherapy treatment and its relevant information: “ you don’t absorb everything that’s being said and an awful lot of information is given to you ” [ 22 ]. People stated that the need to know more information about their cancer, as they were never dared to ask from their clinicians: “ I am a low educated person and come from a rural area; I just follow the doctor’s advice for my health, and I do not dare to ask anything” [ 17 ].

The purpose of this review was to explore patient’s experiences about the chemotherapy adherence. After finalizing the searches, thirteen papers were included in this review that met the inclusion criteria.

The findings of the present review suggest that social support is a crucial element in people’s positive experiences of adhering to chemotherapy. Such support can lead to positive outcomes by providing consistent and timely assistance from family members or healthcare professionals, who play vital roles in maintaining chemotherapy adherence [ 30 ]. Consistent with our study, previous research has highlighted the significant role of family members in offering emotional and physical support, which helps individuals cope better with chemotherapy treatment [ 31 , 32 ]. However, while receiving support from family members reinforces individuals’ sense of responsibility in managing their treatment and their family, it also instils a desire to survive cancer and undergo chemotherapy. One study found that assuming self-responsibility empowers patients undergoing chemotherapy, as they feel a sense of control over their therapy and are less dependent on family members or healthcare professionals [ 33 ]. A qualitative systematic review reported that support from family members enables patients to become more proactive and effective in adhering to their treatment plan [ 34 ]. This review highlights the importance of maintaining a positive outlook and rational beliefs as essential components of chemotherapy adherence. Positive thinking helps individuals recognize their role in chemotherapy treatment and cope more effectively with their illness by accepting it as part of their treatment regimen and viewing it as a tool for survival. This finding is supported by previous studies indicating that positivity and positive affirmations play critical roles in helping individuals adapt to their reality and construct attitudes conducive to chemotherapy adherence [ 35 , 36 ]. Similarly, maintaining a positive mindset can foster more favourable thoughts regarding chemotherapy adherence, ultimately enhancing adherence and overall well-being [ 37 ].

This review identified side effects as a significant negative aspect of the chemotherapy experience, with individuals expressing concerns about how these side effects affected their ability to perform personal self-care tasks and maintain independent living in their daily lives. Previous studies have shown that participants with a history of chemotherapy drug side effects were less likely to adhere to their treatment regimen due to worsening symptoms, which increased the burden of medication side effects [ 38 , 39 ]. For instance, cancer patients who experienced minimal side effects from chemotherapy were at least 3.5 times more likely to adhere to their treatment plan compared to those who experienced side effects [ 40 ]. Despite experiencing side effects, patients were generally willing to accept and adhere to their treatment program, although one study in this review indicated that side effects made some patients unable to maintain treatment adherence. Side effects also decreased quality of life and imposed restrictions on lifestyle, as seen in another study where adverse effects limited individuals in fulfilling daily commitments and returning to normal levels of functioning [ 41 ]. Additionally, unmet needs regarding information on patients’ needs and expectations were common. Healthcare professionals were considered the most important source of information, followed by consultation with the internet. Providing information from healthcare professionals, particularly nurses, can support patients effectively and reinforce treatment adherence [ 42 , 43 ]. Chemotherapy patients often preferred to base their decisions on the recommendations of their care providers and required adequate information retention. Related studies have highlighted that unmet needs among cancer patients are known factors associated with chemotherapy adherence, emphasizing the importance of providing precise information and delivering it by healthcare professionals to improve adherence [ 44 , 45 ]. Doubts about the efficacy of chemotherapy treatment, as the disease may remain latent, were considered negative experiences. Despite these doubts, patients continued their treatment, echoing findings from a study where doubts regarding efficacy were identified as a main concern for chemotherapy adherence. Further research is needed to understand how doubts about treatment efficacy can still encourage patients to adhere to chemotherapy treatment.

Strengths and limitation

The strength of this review lies in its comprehensive search strategy across databases to select appropriate articles. Additionally, the use of JBI guidelines provided a comprehensive and rigorous methodological approach in conducting this review. However, the exclusion of non-English studies, quantitative studies, and studies involving adolescents and children may limit the generalizability of the findings. Furthermore, this review focuses solely on chemotherapy treatment and does not encompass other types of cancer treatment.

Conclusion and practical implications

Based on the discussion of the findings, it is evident that maintaining a positive mentality and receiving social support can enhance chemotherapy adherence. Conversely, experiencing treatment side effects, concerns about efficacy, and unmet information needs may lead to lower adherence. These findings present an opportunity for healthcare professionals, particularly nurses, to develop standardized approaches aimed at facilitating chemotherapy treatment adherence, with a focus on providing comprehensive information. By assessing patients’ needs, healthcare professionals can tailor approaches to promote chemotherapy adherence and improve the survival rates of people living with cancer. Raising awareness and providing education about cancer and chemotherapy treatment can enhance patients’ understanding of the disease and its treatment options. Utilizing videos and reading materials in outpatient clinics and pharmacy settings can broaden the reach of educational efforts. Policy makers and healthcare providers can collaborate to develop sustainable patient education models to optimize patient outcomes in the context of cancer care. A deeper understanding of individual processes related to chemotherapy adherence is necessary to plan the implementation of interventions effectively. Further research examining the experiences of both adherent and non-adherent patients is essential to gain a comprehensive understanding of this topic.

Data availability

The datasets used and/or analysed during the current study available from the corresponding author on reasonable request. on our submission system as well.

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First author (AR) and second author (ST) conceived the review and the second author oversight for all stages of the review provided by the second author. All authors (AR), (ST), (WG) and (SK) undertook the literature search. Data extraction, screening the included papers and quality appraisal were undertaken by all authors (AR), (ST), (WG) and (SK). First and second authors (AR) and (ST) analysed the data and wrote the first draft of the manuscript and revised the manuscript and all authors (AR), (ST), (WG) and (SK) approved the final version of the manuscript.

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Rashidi, A., Thapa, S., Kahawaththa Palliya Guruge, W. et al. Patient experiences: a qualitative systematic review of chemotherapy adherence. BMC Cancer 24 , 658 (2024). https://doi.org/10.1186/s12885-024-12353-z

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Universal Health Coverage – Exploring the What, How, and Why Using Realistic Review

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Background Universal health coverage (UHC) is a critical target in many health system strategies to achieve the ‘good health and wellbeing’. Evidence on the meaning and scope of UHC and the strategies required to achieve it are needed, as variations in its understanding and implementation have risen. We synthesised evidence on the meaning, components, significance, and strategies of UHC.

Methods A review of evidence was conducted based on realist synthesis. We searched PubMed, EMBASE, Scopus, and Web of Science for published materials and websites for grey literature. We have followed some steps: define the scope of the review and develop initial programme theory, search for evidence, data extraction, and synthesis of evidence.

Results Universal coverage, universal health, universal healthcare, universal access, and insurance coverage are used interchangeably with UHC. It is a legal notion that embodies a human rights-based and collaborative approach to ensure fair and comprehensive health care services. Universal health coverage is relevant for three macro reasons: first, it prevents and reduces the impact of diseases; second, it addresses inequality and promotes equity; and third, it is key for global health security. Various mechanisms involved to implement UHC, such as health insurance, social health protection, digital financing systems, value-based care, private sectors, civil societies, partnership, primary health care, and reciprocal health care systems.

Conclusions Universal health coverage is a multifaceted concept that can be expressed by various terms in different contexts. Universal health coverage is a political and ethical imperative that aims to promote health equity and protect human dignity across different levels of society. It is essential in preventing diseases and serving a crucial role in global health security. Practically, UHC is not truly universal, as it does not include all services under its scheme and varies across countries. This requires consistent advocacy, strategic and operational research as well as political will to ensure UHC.

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All Business Strategies Fall into 4 Categories

• Jerome Barthelemy

Some are more creative than others.

The problem with strategy frameworks is that although they can help you determine whether an opportunity is attractive or whether a given strategy is likely to work, they generally don’t help you in the task of identifying the opportunity or crafting the strategy in the first place. This article introduces a framework, built on an in-depth analysis of the creativity literature, that aims to fill that gap by providing a systematic approach to identifying potential strategies. The framework categorizes all strategies into the following four groups, from the least creative to the most creative: adapting an existing industry strategy, combining different existing industry strategies, importing strategies from other industries, and creating a brand new strategy from scratch.

The problem with strategy frameworks is that although they can help you determine whether a given opportunity is attractive or whether a particular strategy is likely to work, they generally don’t help you in the task of identifying the opportunity or crafting the strategy in the first place. As the legendary strategy expert Gary Hamel put it: “ The dirty little secret of the strategy industry is that it doesn’t have any theory of strategy creation .”

• Jérôme Barthélemy is Executive Vice-President, Dean for Post Experience Programs, Corporate Programs and Relations and Professor of Strategy and Management at ESSEC Business School. He is the author of Myths of Strategy (Kogan Page, 2023)

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