Last updated: 26 October 2025 

What's new in this update

This chapter has been substantially updated.

Introduction

Qualitative research can make an important contribution to health technology assessment (Carroll 2017, Szabo 2023). This can involve the identification and review of qualitative evidence (qualitative evidence synthesis) designed to explain differences in intervention effect, to explore aspects of implementation or to capture evidence of patient experience or preference (Booth 2016, Booth 2017, Centre for Reviews and Dissemination 2009). Whilst the integration of qualitative evidence in health technology assessment is not common, its value is increasingly recognised as useful (Booth 2016, Murphy, 1998).

The process of identifying qualitative research is less clear than for identifying studies reporting randomised controlled trials. Poor reporting of qualitative research in studies (Centre for Reviews and Dissemination 2009, Grant 2004, Gorecki 2010), limited indexing of studies (Centre for Reviews and Dissemination 2009, Toye 2014, Shaw 2004), apparent confusion in the reporting of methods of data collection (interviews, focus groups) and synthesis (e.g. thematic synthesis, meta-ethnography) in studies (Evans 2002, Campbell 2003), and a need to search beyond primary biomedical databases (Dixon‐Woods 2001, Atkins 2008), are some of the reasons that qualitative research is more challenging to identify (Booth 2016). Moreover, methodological guidance on ‘how to’ literature search for qualitative research is limited where it does exist (c.f. Centre for Reviews and Dissemination 2009, Noyes 2019) (Booth 2016).

Research supporting the process of searching for qualitative research was reviewed and summarised in a systematic methodological review (Booth 2016). This review continues to provide a framework for identification of literature in subsequent updates. However, many of the processes described in that review will be moderated or refined by the searching chapter in the planned Cochrane-Campbell Handbook of Qualitative Evidence Synthesis (Stansfield 2026).

Together with many of the following source publications, we recommend contacting an information professional or researcher with specific experience in literature searching for qualitative research (Justesen 2021). This recommendation has been reinforced by 2024 guidance on rapid qualitative evidence synthesis (rQES) (Booth 2024).

Sources to search

Bibliographic

A consensus is still to be reached on the number of databases, or which databases, to search when conducting a literature search for qualitative research. A retrospective case-study that considered the contribution of CINAHL in identifying qualitative research, indicated review teams typically searched between 3 and 20 databases (Wright 2015).

The CRD handbook (Centre for Reviews and Dissemination 2009) recommends that searches should include MEDLINE, Embase, CINAHL (Cumulative Index to Nursing and Allied Health) and PsycINFO for reviews and primary studies, It is true that MEDLINE and CINAHL are the most frequently searched sources to identify qualitative research (Hannes 2012, Dixon-Woods 2007) and their value has been demonstrated empirically (Subirana 2005). However, Horton et al caution that traditional reliance on MEDLINE, CINAHL, PsycINFO, and EMBASE may not be sufficient (Horton 2025). They highlight that supplemental databases like Scopus, Web of Science, and ProQuest can significantly enhance coverage, especially for context-rich or discipline-specific qualitative studies.

Similarly, Frandsen et al have demonstrated that searching PubMed and EMBASE is not sufficient (Frandsen 2025). In their study of 11,822 included publications from 343 Cochrane reviews across public health, incontinence, hepato-biliary, and stroke) they found that PubMed and Embase together covered 71.5% of included publications on average. Subject coverage varied by specialty group from 64.5% to 75.9%. Supplementary databases increased retrieval to 94.2%, with Cochrane Library providing the highest additional coverage at 62.9% of residual publications. They conclude that while PubMed and Embase provide substantial coverage, supplementary databases are essential for comprehensive literature searches, particularly databases relevant to specific specialties and document types.

A study comparing search strategies on MEDLINE, EMBASE, CINAHL, and PsycINFO demonstrated the value of CINAHL in providing differentiated subject headings to retrieve qualitative studies in dementia (Rogers 2017). However, the extent to which this finding relates only to dementia-specific search strategies is unclear, thus indicating a need for further investigation. Seventy-one qualitative systematic reviews (927 qualitative studies) have been analysed across nine bibliographic databases (Frandsen 2019). 94.4% of the qualitative studies were indexed in at least one database. Maximum recall with two databases approached 90% (89.1%), with three databases recall increases to 92% and maximum recall with four databases was 93.1%. A long tail of the remaining 6.9% of the publications were scattered across five databases (1.3%) or not indexed in any of the nine databases (5.6%) (Frandsen 2019).

Analysis of 23 systematic reviews on diabetes found that searching a combination of PubMed, Embase and CINAHL resulted in an overall recall rate of 99.3%, while adding PsycINFO increased overall recall to 99.8% (Justesen 2021). As a consequence, the authors recommend a combination of CINAHL, PubMed, Embase and PsycINFO (Justesen 2021). However, it should be noted that retrospective studies of yields from reviews may optimise the yield of database searching in the absence of extensive non-database strategies that increase the denominator.

The Social Science Citation index (SSCI, Clarivate Analytics) is also commended as a valuable resource for study identification (DeJean 2016). Reviewers are, however, strongly encouraged to identify specialist databases that relate to their review topic, together with databases that host particular types of publications or content e.g. dissertation abstracts, book chapters, theses and unpublished reports. Horton et al (Horton 2025) reinforce the view (Justesen 2021) that no single database offers comprehensive coverage across all qualitative domains (Horton 2025). Instead, they conclude that searchers should tailor database selection based on the subject area, population, and intervention context of the review.

Where resources are limited the searcher should aim to access as diverse a sample of relevant databases as possible, for example capturing different disciplinary or professional perspectives and different literature types, as this will best further the objectives of the subsequent synthesis.

Specifically, the Cochrane guidance on rapid/resource-limited QES (rQES)(Booth 2024) cites the empirical evidence on database combinations (Frandsen 2019) that comprise Scopus plus CINAHL or Scopus plus ProQuest Dissertations and Theses Global (as optimal two-database combinations) and Scopus plus CINAHL plus ProQuest Dissertations and Theses Global (as an optimal three-database combination) with both choices retrieving between 89% and 92% of relevant studies (Frandsen 2019).

If resources allow, searches should also include one or two specialised databases (e.g. social science databases, specialist discipline databases or regional or institutional repositories) (Booth 2016, Booth 2019a). Even when resources are limited, the information specialist should factor in time for peer review of at least one search strategy (Booth 2024).

Supplementary search methods

Given the issues with identifying qualitative research (summarised above), supplementary search methods are considered particularly useful (Stansfield 2026, Cooper 2017a, Pedersen 2023, Frandsen 2023). Supplementary search methods such as internet searching, personal contact with topic experts, forward citation searching and reference checking, may prove valuable since they may identify content not indexed in bibliographic databases and they do not require precise search terms to identify studies for inclusion (Justesen 2021).

The value of supplementary searching has been affirmed by a study (Frandsen 2023) that explored whether citation searches and alternative search strategies were able to identify otherwise irretrievable relevant publications. The study also sought to investigate the additional yield when conventional database searches were combined with such supplementary search strategies (Frandsen 2023).

From 10 eligible reviews that included publications not available in PubMed, 61 publications were retrievable through conventional database searches, and 37 were nonidentifiable (Frandsen 2023). The 61 publications were then used as a springboard for possible identification of the 37 publications via a wide choice of supplementary strategies. Citation searches in Scopus, Citationchaser (Haddaway 2022) and CoCites identified 21/37 remaining publications. The PubMed "Cited by" function did not identify any of these. The alternative search strategies (PubMed "Similar articles" plus Scopus "Related documents" functions) identified 40.5% of the publications. Together, these supplementary search strategies identified 67.6% of the publications, for a combined overall retrieval of 87.1%. Therefore, citation searches and Related/Similar document functions increased the retrieval potential for qualitative reviews from approximately two-thirds to almost 90% of publications (Frandsen 2023).

Similarly, checking reference lists of included articles resulted in 2.5 more included references than by database searches alone (Justesen 2021). A multipronged approach of supplementary searching has been recommended (Campbell 2003). A worked example demonstrates supplementary searching for a within a Cochrane public health qualitative evidence synthesis (Cooper 2017b).

Guidance on rapid qualitative evidence synthesis recommends use of grey literature and supplementary searching where the aim is to retrieve studies from diverse contexts and populations (Booth 2024). Searches for ‘grey literature’ should selectively target appropriate types of grey literature (such as theses or process evaluations) and supplemental searches, including citation chaining or Related Articles features (Cooper 2017b). The first Cochrane rQES reported that searching reference lists of key papers yielded an extra 30 candidate papers for review (Houghton 2020). However, the team documented exclusion of grey literature as a limitation of their review.

Designing search strategies

Differences between conducting quantitative and qualitative research impact on the design of search strategies for these different types of literature (Mackay 2007). Whilst quantitative research and searches take a linear and structured route, qualitative research searches often use emerging results to inform subsequent strategies in an iterative manner (Mackay 2007). As a consequence, qualitative searches may take a long time to plan, be labour intensive to undertake and challenging to replicate (Booth 2016).

Search strategy design

Designing the search strategy may necessitate a different question formulation and search strategy structure from the Population, Intervention, Comparator, and Outcome (PICO) structure used by systematic reviews of intervention effectiveness (Cooper 2018b). Table 1 summarises alternative structures to PICO (Booth 2016, Booth 2019b).

Frandsen and colleagues (Frandsen 2021) explored the presence of elements from conceptual frameworks in publication titles, abstracts, and controlled vocabulary in CINAHL and PubMed against a gold standard of qualitative reviews and their included studies.  From a sample of 101 publications they report high relative recall of conceptual framework elements or patient/population (99%) and research type (97%) and lower recall for intervention/phenomenon of interest (74%), outcome (79%), and context (61%). The authors conclude that, apart from patient/population and research type elements, other elements should be used with care (Frandsen 2023).

Search filters

Qualitative search strategies seek to optimise a balance between the sensitivity of not missing relevant items against the specificity of only retrieving the most relevant items whilst, at the same time, keeping the yield within manageable resources. Search filters may help researchers to achieve this balance.

Search filters for commonly used databases (e.g. MEDLINE, Embase, PsycINFO and CINAHL) are reported on the ISSG search filters resource. Whilst researchers view the use of search filters with caution in qualitative evidence synthesis (Grant 2004), the performance of qualitative search filters is acceptable, although inferior to search filters to identify trials (Booth 2016). An overview of thirteen search filters to identify qualitative research papers in MEDLINE (Wagner 2020) reported a sensitivity of 93.63% for a search filter developed at McMaster University (Wong Sharon 2004). For precision, the Medical Subject Heading “qualitative research” performed best at 2.15% but at the expense of sensitivity, retrieving less than a quarter of relevant studies (22.56%) (Wagner 2020). A University of Texas filter offered the optimal balance with a sensitivity of 81.96% and a precision of 0.80% (UTHealth 2021). An associated study extended evaluation to twelve search filters for PsycINFO and fifteen for CINAHL (Rosumeck 2020). Filters demonstrating the best sensitivity (>80%)  and precision ratio have been developed for PsycINFO (McKibbon 2006) and CINAHL (Wilczynski 2007) and subsequently evaluated (Rosumeck 2020).

Interestingly, short filters (e.g. qualitative OR interview* OR Interviews/ OR findings) have, in a limited number of case studies (Gorecki 2010, Flemming 2006), been demonstrated to perform comparably with extensive filters. Reasons, although unclear, may relate to less common qualitative terms retrieving records already retrieved by common terms, impairing their added value and unique yield. Unlike trials there has been no retrospective effort to index qualitative research and the MeSH term for "qualitative research" was only introduced in the year 2003.

Filters may miss relevant studies due to inconsistent indexing and poor metadata (Horton 2025). Qualitative methods are often underreported in titles and abstracts, making them hard to capture with filters alone (Horton 2025). So, rather than endorsing a single filter, authors recommend piloting and iteratively refining filters based on topic and database and encourage testing filter sensitivity against known sets of included studies to assess performance (Horton 2025). Likewise, filters should be used in combination with other techniques, such as citation chasing, consulting experts and searching grey literature (Horton 2025).

It is important to note that there is no dominant search filter used or recommended in practice to identify qualitative research. Unlike reviews of intervention effectiveness, where the Cochrane HSSS is rightly dominant, a researcher using a qualitative literature search filter needs to carefully match their choice of filter to the purpose of the literature search which will, in turn, vary by review (Booth 2016).

Comprehensive literature searching?

For reviews of intervention effectiveness, a comprehensive, exhaustive literature search for studies is commonly perceived as the default requirement. Researchers have demonstrated that even a single missing study may impact negatively on the precision of an estimate of intervention effectiveness.

Qualitative evidence synthesis does not offer such a demonstrable impact of a missing study. A complete Interpretation of a phenomenon of interest may still be possible in the absence of missing studies, particularly if missing studies share the characteristics ("more of the same") of studies already represented within the sample. The value of comprehensive literature searches is less clear. Further research on how to approach these issues is indicated (Benoot 2016, Ames 2019).

Increasingly, alternatives to comprehensive searching, relying on purposive or theoretical sampling, are being proposed. Where the intent of a qualitative evidence synthesis is interpretive, rather than descriptive, literature searches for qualitative research may not need to aspire to comprehensive coverage (Booth 2001). The planned Cochrane-Campbell Handbook of Qualitative Evidence Synthesis (early 2026) carries a first-ever chapter on sampling together with implications for searching and subsequent reporting (Ames 2026).

On the other hand, unintentional omission of studies capturing particular perspectives, professions or geographical contexts may miss Important nuances (Carroll 2012) reinforcing the point that diversity within the relevant sample may be the most Important driver for the literature search strategy.

Reporting

Reporting the process of literature searching in qualitative evidence synthesis is no less important than for reviews of intervention effectiveness; more so if alternatives to comprehensive sampling are to be used and justified. With careful and disciplined documentation of the search processes by the searcher, producing a transparent account of literature searching is possible even for Iterative searches (Booth 2016). Specifically Horton et al advocate for transparent documentation of filter use, including rationale, structure, and performance metrics (Horton 2025).

Reporting standards for qualitative evidence synthesis, include eMERGe for meta-ethnography (France 2019), RAMESES for meta-narrative approaches (Wong 2013a) (alongside its higher profile guidance for realist syntheses (Wong 2013b) and ENTREQ for generic approaches to QES (Tong 2012). All these reporting standards include items relating to documentation of the search process. In late 2025 a methodology systematic review and Delphi questionnaire, funded by the UK Medical Research Council, were undertaken to inform PRISMA-QES – an evidence-based reporting guideline for most types of QES (excluding meta-ethnography). It is anticipated that this will render ENTREQ obsolete (https://osf.io/37krs/) .

Most reporting standards derive from the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) reporting standard and so the number of studies identified by various literature search methods should be reported within a flowchart (Page 2021).  Reporting of search strategies should also follow generic reporting guidance. While not a reporting standard per se, the EQUATOR Inventory includes a prototypic structure for reporting search strategies, STARLITE (Booth 2006b), compiled from almost 50 published QES:

Sampling strategy

Type of study

Approaches

Range of years

Limits

Inclusion and exclusions

Terms used

Electronic sources

The use of a search narrative has been recommended to improve the transparency of literature searching (Craven 2011, Cooper 2018a). Whilst not specific to qualitative literature searching, providing detail on the conceptual and contextual details of the literature searching process is likely to hold value in explaining the conception and execution of the search strategy in a clear and transparent way (Benoot 2016).

Reference list

Ames 2019

Ames H, Glenton C, Lewin S. Purposive Sampling in a Qualitative Evidence Synthesis: A Worked Example From a Synthesis on Parental Perceptions of Vaccination Communication. BMC Medical Research Methodology. 2019;19(1). [Publication appraisal]

Ames 2026

Ames H, Booth A, Noyes J. Sampling for Studies. In: Noyes Jane HA, editor. Cochrane Campbell Handbook of Qualitative Evidence Synthesis. London: Wiley; 2026. 

Atkins 2008

Atkins S, Lewin S, Smith H, Engel M, Fretheim A, Volmink J. Conducting a meta-ethnography of qualitative literature: lessons learnt. BMC Medical Research Methodology. 2008;8(1).

Benoot 2016

Benoot C, Hannes K, Bilsen J. The use of purposeful sampling in a qualitative evidence synthesis: A worked example on sexual adjustment to a cancer trajectory. BMC Medical Research Methodology. 2016;16(1). 

Booth 2001

Booth A, editor Cochrane or cock-eyed? How should we conduct systematic reviews of qualitative research. Proceedings of the Qualitative Evidence-based Practice Conference, Taking a Critical Stance; 2001: Coventry University Coventry.

Booth 2006a

Booth A. Australian supermodel?—A practical example of evidence‐based library and information practice (EBLIP). Health Information & Libraries Journal. 2006;23(1):a-72.

Booth 2006b

Booth A. "Brimful of STARLITE": toward standards for reporting literature searches.  J Med Libr Assoc. 2006;94(4):421-9, e205. [Publication appraisal]

Booth 2015

Booth A, Carroll C. Systematic searching for theory to inform systematic reviews: is it feasible? Is it desirable? Health Information & Libraries Journal. 2015;32(3):220-35.

Booth 2016

Booth A. Searching for qualitative research for inclusion in systematic reviews: a structured methodological review. Systematic Reviews. 2016;5(1). [Publication appraisal]

Booth 2017

Booth A. Qualitative Evidence Synthesis. Patient Involvement in Health Technology Assessment: Springer Singapore; Adis, 2017. p. 187-99.

Booth 2019a

Booth A, Mshelia S, Analo CV, Nyakang'o SB. Qualitative evidence syntheses: Assessing the relative contributions of multi‐context and single‐context reviews. Journal of Advanced Nursing. 2019;75(12):3812-22.

Booth 2019b

Booth A, Noyes J, Flemming K, Moore G, Tunçalp Ö, Shakibazadeh E. Formulating questions to explore complex interventions within qualitative evidence synthesis. BMJ Glob Health. 2019;4(Suppl 1):e001107.

Booth 2024

Booth A, Sommer I, Noyes J, Houghton C, Campbell F. Rapid reviews methods series: guidance on rapid qualitative evidence synthesis. BMJ Evidence-Based Medicine. 2024;29(3):194-200.

Campbell 2003

Campbell R, Pound P, Pope C, Britten N, Pill R, Morgan M, et al. Evaluating meta-ethnography: a synthesis of qualitative research on lay experiences of diabetes and diabetes care. Social Science & Medicine. 2003;56(4):671-84.

Carroll 2012

Carroll C, Booth A, Lloyd-Jones M. Should We Exclude Inadequately Reported Studies From Qualitative Systematic Reviews? An Evaluation of Sensitivity Analyses in Two Case Study Reviews. Qualitative Health Research. 2012;22(10):1425-34. [Publication appraisal]

Carroll 2017

Carroll C. Qualitative evidence synthesis to improve implementation of clinical guidelines. BMJ. 2017:j80.

Centre for Reviews & Dissemination 2009

Centre for Reviews & Dissemination. Systematic reviews: CRD’s guidance for undertaking reviews in healthcare . York: Centre for Reviews and Dissemination, University of York; 2009. 

Cooke 2012

Cooke A, Smith D, Booth A. Beyond PICO. Qualitative Health Research. 2012;22(10):1435-43.

Cooper 2017a

Cooper C, Booth A, Britten N, Garside R. A comparison of results of empirical studies of supplementary search techniques and recommendations in review methodology handbooks: a methodological review. Systematic Reviews. 2017;6(1). [Publication appraisal]

Cooper 2017b

Cooper C, Lovell R, Husk K, Booth A, Garside R. Supplementary search methods were more effective and offered better value than bibliographic database searching: A case study from public health and environmental enhancement. Research Synthesis Methods. 2017;9(2):195-223. 

Cooper 2018a

Cooper C, Dawson S, Peters J, Varley‐Campbell J, Cockcroft E, Hendon J, et al. Revisiting the need for a literature search narrative: A brief methodological note. Research Synthesis Methods. 2018;9(3):361-5.

Cooper 2018b

Cooper C, Booth A, Varley-Campbell J, Britten N, Garside R. Defining the process to literature searching in systematic reviews: a literature review of guidance and supporting studies. BMC Medical Research Methodology. 2018;18(1). [Publication appraisal]

Craven 2011

Craven J, Levay P. Recording database searches for systematic reviews - What is the value of adding a narrative to peer-review checklists? A case study of NICE interventional procedures guidance. Evidence Based Library and Information Practice. 2011;6(4):72-87. [Publication appraisal]

DeJean 2016

DeJean D, Giacomini M, Simeonov D, Smith A. Finding Qualitative Research Evidence for Health Technology Assessment. Qualitative Health Research. 2016;26(10):1307-17. [Publication appraisal]

Denyer 2009

Denyer D, Tranfield D. Producing a systematic review. In: Buchanan DA BAe, editor. The SAGE handbook of organizational research methods. London: SAGE Publications Ltd 2009.

Dixon-Woods 2001

Dixon‐Woods M, Fitzpatrick R, Roberts K. Including qualitative research in systematic reviews: opportunities and problems. Journal of Evaluation in Clinical Practice. 2001;7(2):125-33.

Dixon-Woods 2007

Dixon-Woods M, Booth A, Sutton AJ. Synthesizing qualitative research: a review of published reports. Qualitative Research. 2007;7(3):375-422.

Evans 2002

Evans D. Database searches for qualitative research. J Med Libr Assoc. 2002;90(3):290-3.

Flemming 2006

Flemming K, Briggs M. Electronic searching to locate qualitative research: evaluation of three strategies. Journal of Advanced Nursing. 2006;57(1):95-100. 

France 2019

France EF, Cunningham M, Ring N, Uny I, Duncan EAS, Jepson RG, et al. Enhancing transparency in reporting the synthesis of qualitative research: ENTREQ. BMC Medical Research Methodology. 2019;19(1).

Frandsen 2019

Frandsen TF, Gildberg FA, Tingleff EB. Searching for qualitative health research required several databases and alternative search strategies: a study of coverage in bibliographic databases. Journal of Clinical Epidemiology. 2019;114:118-24. 

Frandsen 2021

Frandsen TF, Lindhardt CL, Eriksen MB. Performance of conceptual framework elements for the retrieval of qualitative health literature: a case study. Journal of the Medical Library Association. 2021;109(3). 

Frandsen 2023

Frandsen TF, Eriksen MB. Supplementary strategies identified additional eligible studies in qualitative systematic reviews. Journal of Clinical Epidemiology. 2023;159:85-91.

Frandsen 2025

Frandsen TF, Moos C, Marino CILH, Eriksen MB. Supplementary databases increased literature search coverage beyond PubMed and Embase. J Clin Epidemiol. 2025 May;181:111704. {Publication appraisal]

Gorecki 2010

Gorecki CA, Brown JM, Briggs M, Nixon J. Evaluation of five search strategies in retrieving qualitative patient‐reported electronic data on the impact of pressure ulcers on quality of life. Journal of Advanced Nursing. 2010;66(3):645-52. [Publication appraisal]

Grant 2004

Grant MJ. How does your searching grow? A survey of search preferences and the use of optimal search strategies in the identification of qualitative research. Health Information & Libraries Journal. 2004;21(1):21-32.

Haddaway 2022

Haddaway NR, Grainger MJ, Gray CT. Citationchaser: A tool for transparent and efficient forward and backward citation chasing in systematic searching. Research Synthesis Methods. 2022;13(4):533-45.

Hannes 2012

Hannes K, Macaitis K. A move to more systematic and transparent approaches in qualitative evidence synthesis: update on a review of published papers. Qualitative Research. 2012;12(4):402-42.

Horton 2025

Horton J, Kaunelis D, Rabb D, Smith A. What’s beyond the core? Database coverage in qualitative information reveal. Journal of the Medical Library Association. 2025;113(1):49-57. [Publication appraisal]

Houghton 2020

Houghton C, Meskell P, Delaney H, Smalle M, Glenton C, Booth A, et al. Barriers and facilitators to healthcare workers’ adherence with infection prevention and control (IPC) guidelines for respiratory infectious diseases: a rapid qualitative evidence synthesis. Cochrane Database of Systematic Reviews. 2020;2020(8).

Justesen 2021

Justesen T, Freyberg J, Schultz ANØ. Database selection and data gathering methods in systematic reviews of qualitative research regarding diabetes mellitus - an explorative study. BMC Medical Research Methodology. 2021;21(1). [Publication appraisal]

McKibbon 2006

McKibbon KA, Wilczynski NL, Haynes RB. Developing Optimal Search Strategies for Retrieving Qualitative Studies in PsycINFO. Evaluation & the Health Professions. 2006;29(4):440-54. [Publication appraisal]

Mackay 2007

Mackay G. Is there a need to Differentiate between Qualitative and Quantitative Searching Strategies for Literature Reviewing? Qualitative Social Work. 2007;6(2):231-41.

Major 2012

Major CH, Savin-Baden M. Designing the synthesis.  An Introduction to Qualitative Research Synthesis: Routledge; 2012. p. 43-55.

Methley 2014

Methley AM, Campbell S, Chew-Graham C, McNally R, Cheraghi-Sohi S. PICO, PICOS and SPIDER: a comparison study of specificity and sensitivity in three search tools for qualitative systematic reviews.  BMC Health Services Research. 2014;14(1). [Publication appraisal]

Murphy 1998

Murphy, Dingwall, Greatbatch, Parker, Watson. Qualitative research methods in health technology assessment: a review of the literature. Health Technology Assessment. 1998;2(16).

Noyes 2019

Noyes J, Booth A, Cargo M, Flemming K, Harden A, Harris J, et al. Chapter 21: Qualitative evidence. Cochrane Handbook for Systematic Reviews of Interventions: Wiley; 2019. p. 525-45.

Page 2021

Page MJ, McKenzie JE, Bossuyt PM, Boutron I, Hoffmann TC, Mulrow CD, et al. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. Systematic Reviews. 2021;10(1).

Pedersen 2023

Pedersen ML, Tingleff EB. Grey literature and comprehensive search strategies are important in qualitative syntheses. Journal of Clinical Nursing. 2023;32(19-20):7640-1.

Petticrew 2006

Petticrew M, Roberts H. How to find the studies: the literature search Systematic Reviews in the Social Sciences. London: Wiley; 2006.

Richardson 1995

Richardson WS, Wilson MC, Nishikawa J, Hayward RS. The well-built clinical question: a key to evidence-based decisions. ACP journal club. 1995;123(3):A12-3.

Rogers 2017

Rogers M, Bethel A, Abbott R. Locating qualitative studies in dementia on MEDLINE, EMBASE, CINAHL, and PsycINFO: A comparison of search strategies. Research Synthesis Methods. 2017;9(4):579-86. 

Rosumeck 2020

Rosumeck S, Wagner M, Wallraf S, Euler U. A validation study revealed differences in design and performance of search filters for qualitative research in PsycINFO and CINAHL. Journal of Clinical Epidemiology. 2020;128:101-8. 

Sandelowski 2006

Sandelowski MJ, Barroso J. Searching for and retrieving qualitative research reports. In: Sandelowski MJ, Barroso, Julie, editor. Handbook for synthesizing qualitative research: Springer publishing company; 2006.

Shaw 2004

Shaw RL, Booth A, Sutton AJ, Miller T, Smith JA, Young B, et al. Finding qualitative research: an evaluation of search strategies. BMC Medical Research Methodology. 2004;4(1). [Publication appraisal]

Stansfield 2026

Stansfield CC, M; Booth A;. Searching and identifying studies. In: Noyes J HA, editor. Cochrane Campbell Handbook for Qualitative Evidence Synthesis. London: Wiley; 2026.

Stern 2014

Stern C, Jordan Z, McArthur A. Developing the Review Question and Inclusion Criteria. AJN, American Journal of Nursing. 2014;114(4):53-6.

Subirana 2005

Subirana M, Solá I, Garcia JM, Gich I, Urrútia G. A nursing qualitative systematic review required MEDLINE and CINAHL for study identification. Journal of Clinical Epidemiology. 2005;58(1):20-5. 

Szabo 2023

Szabo SM, Hawkins NS, Germeni E. The extent and quality of qualitative evidence included in health technology assessments: a review of submissions to NICE and CADTH. Int J Technol Assess Health Care. 2023;40(1):e6.

Tong 2012

Tong A, Flemming K, McInnes E, Oliver S, Craig J. Enhancing transparency in reporting the synthesis of qualitative research: ENTREQ. BMC Medical Research Methodology. 2012;12(1).

Toye 2014

Toye F, Seers K, Allcock N, Briggs M, Carr E, Barker K. Meta-ethnography 25 years on: challenges and insights for synthesising a large number of qualitative studies. BMC Medical Research Methodology. 2014;14(1).

Wagner 2020

Wagner M, Rosumeck S, Küffmeier C, Döring K, Euler U. A validation study revealed differences in design and performance of MEDLINE search filters for qualitative research. Journal of Clinical Epidemiology. 2020;120:17-24. [Publication appraisal]

Wilczynski 2007

Wilczynski NL, Marks S, Haynes RB. Search Strategies for Identifying Qualitative Studies in CINAHL. Qualitative Health Research. 2007;17(5):705-10. [Publication appraisal]

Wildridge 2002

Wildridge V, Bell L. How CLIP became ECLIPSE: a mnemonic to assist in searching for health policy/management information. Health Information & Libraries Journal. 2002;19(2):113-5.

Wong 2004

Wong SSL, Wilczynski NL, Haynes RB. Developing Optimal Search Strategies for Detecting Clinically Relevant Qualitative Studies in MEDLINE. Studies in Health Technology and Informatics. 2004;107:311-316. 

Wright 2015

Wright K, Golder S, Lewis-Light K. What value is the CINAHL database when searching for systematic reviews of qualitative studies? Systematic Reviews. 2015;4(1). [Publication appraisal]

UT Health 2021

UT Health Houston. Search Filters for Various Databases: Ovid Medline. Houston, US-TX: UTHealth [updated Last Updated: Jul 12, 2021. Available from: http://libguides.sph.uth.tmc.edu/search_filters/ovid_medline_filters .

Wong 2013a

Wong G, Greenhalgh T, Westhorp G, Buckingham J, Pawson R. RAMESES publication standards: meta-narrative reviews.  BMC Medicine. 2013;11(1).

Wong 2013b

Wong G, Greenhalgh T, Westhorp G, Buckingham J, Pawson R. RAMESES publication standards: realist syntheses. BMC Medicine. 2013;11(1).