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Systematic Reviews & Other Syntheses

Welcome!

The purpose of this guide is to connect you with useful information and resources for embarking on a systematic review or other type of synthesis, with a focus on searching for studies and managing your results.

Please note: some hyperlinked resources are provided by Queen's University Library and may not be available to non-affiliates. Queen's affiliates viewing this guide from off-site may need to login to the library's off-campus access to view the full contents of certain electronic books and articles.

Types of Syntheses

Knowledge syntheses, also known as syntheses, are rigorously conducted literature reviews of the research evidence. When systematic reviews were the first type of synthesis to appear in the health care literature back in the 1970s, the main objective was to synthesize quantitative research studies. Limitations of traditional systematic reviews and meta-analyses have led to the adaptation of syntheses to include: qualitative systematic reviews, mixed-methods reviews, rapid reviews, network meta-analyses, scoping reviews and realist reviews. While many syntheses begin with a clear question, their methodologies and the types of research evidence synthesized to answer the question can be quite different.

To help determine the most appropriate type of synthesis for your research question and purpose, you may find it helpful to consult the following:

Systematic Reviews

A systematic review attempts to identify, select, synthesize, and appraise all evidence on a given research question in a systematic and transparent manner. (Note: before embarking on a systematic review, it is important to conduct a literature search to determine whether or not a systematic review has already been published on your topic. If there is already a recent systematic review on your topic, it may be difficult to publish a similar systematic review.) To help ensure your systematic review is of high-quality, consider the criteria for assessing systematic reviews presented in the AMSTAR Checklist (A Measurement Tool to Assess Systematic Reviews). 
 

Introductory videos:


Systematic reviews steps:

*Important: before embarking on a systematic review, make sure that 1) a recent review on the same topic has not already been published, and 2) that a review protocol has not already been registered for the same topic. To check for systematic reviews that have already been published on your topic, search databases such as Ovid MEDLINE/PubMed, Embase, PsycINFO, CINAHL, and even Google Scholar to catch any journal content that is not covered in these databases. You can also search Epistemonikos for published systematic reviews, a freely available resource that attempts to identify all of the systematic reviews relevant for health decision-making. To check for registered (i.e. forthcoming) systematic reviews, search PROSPERO, the international prospective register of systematic reviews. You can also search for registered protocols by systematic review collaborations such as Cochrane, Campbell and the Joanna Briggs Institute. When you are confident that your research will not be duplicating efforts, you are ready to begin your own review.

Eight stages of a systematic review and meta analysis (Uman, 2011):

  1. Formulate the review question
  2. Define inclusion/exclusion criteria
  3. Develop reproducible search strategies and locate studies
  4. Select studies
  5. Extract data
  6. Assess study quality
  7. Analyze and interpret results
  8. Disseminate findings


Systematic review types:

  1. Quantitative systematic reviews include only quantitative research studies
  2. Qualitative systematic reviews include qualitative and/or mixed methods research studies
  3. Mixed methods reviews include both quantitative and qualitative studies

Most often the type of systematic review conducted will depend on the review question. For example, systematic reviews of healthcare interventions are generally quantitative reviews that include research studies in the form of randomized controlled trials. Systematic reviews of patient experiences are generally qualitative reviews that may include qualitative and mixed methods research studies. Mixed methods reviews are utilized to address the limitations of single method reviews, which are frequently too narrow in scope (Peters et al., 2015). "By including diverse forms of evidence from different types of research, mixed methods reviews attempt to maximize the findings - and the ability of those findings to inform policy and practice" (Peters et al., 2015, p. 5).

Cochrane describes five types of Cochrane Reviews:

  1. Intervention reviews assess the benefits and harms of interventions used in healthcare and health policy
  2. Diagnostic test accuracy reviews assess how well a diagnostic test performs in diagnosing and detecting a particular disease
  3. Methodology reviews address issues relevant to how systematic reviews and clinical trials are conducted and reported
  4. Qualitative reviews synthesize qualitative evidence to address questions on aspects other than effectiveness
  5. Prognosis reviews address the probable course or future outcome(s) of people with a health problem


Systematic review timeframe:

Topic: The review topic will also impact the amount of time required to conduct the review. For example, a systematic review on the effectiveness of a relatively new drug therapy may require less time to complete if the search yields a low number of results to screen and if the review itself only includes a small number of studies.

Searching: The amount of time needed to complete this component of the review will depend on: how straight-forward or complex the topic is, the number and type of resources that will be searched (refer to Where to Search), and the searcher's level of expertise. Working with an experienced librarian is highly recommended.

Review team: Estimating how long it will take to complete a systematic review will depend on the review team's availability to work on the review. Systematic review team members may have competing priorities throughout the duration of the systematic review that can delay the process.

Research evidence:

  • A research study found that the median time spent searching was just under 8 hours, including 1.5 hours spent searching the grey literature, while the average time spent searching was approximately 24 hours, of which 6.5 hours were spent searching the grey literature (Saleh et al., 2014). The average number of resources searched was 9, including grey literature resources. Grant funding influenced the amount of time spent searching and institution type impacted the number of resources searched.
     
  • Greenhalgh and Peacock (2005) found that: "Electronic searching, including developing and refining search strategies and adapting these to different databases, took about two weeks of specialist librarian time..." (p1065).

Scoping Reviews

"Scoping studies aim to map rapidly the key concepts underpinning a research area and the main sources and types of evidence available, and can be undertaken as stand-alone projects in their own right, especially where an area is complex or has not been reviewed comprehensively before" (Mays et al., 2001, p. 194).

The following articles describe the purpose and methods of scoping reviews in detail:

Peters, M. D., Godfrey, C. M., Khalil, H., McInerney, P., Parker, D., & Soares, C. B. (2015). Guidance for conducting systematic scoping reviews. International journal of evidence-based healthcare, 13(3), 141-146.

Arksey, H., & O'Malley, L. (2005). Scoping studies: towards a methodological framework. International Journal of Social Research Methodology, 8(1), 19-32. doi:10.1080/1364557032000119616

Peters, M., Godfrey, C., McInerney, P., Soares, C., Hanan, K., & Parker, D. (2015). The Joanna Briggs Institute reviewers' manual 2015: methodology for JBI scoping reviews.

Bibliography

Cochrane. (n.d.). About Cochrane reviews. Retrieved May 11, 2015, from http://www.cochranelibrary.com/about/about-cochrane-systematic-reviews.html


Grant, M. J., & Booth, A. (2009). A typology of reviews: an analysis of 14 review types and associated methodologies. Health Information & Libraries Journal, 26(2), 91-108.

Greenhalgh, T., & Peacock, R. (2005). Effectiveness and efficiency of search methods in systematic reviews of complex evidence: audit of primary sources. BMJ: British Medical Journal, 331(7524), 1064-1065.
 

Grimshaw, J. (2010). A guide to knowledge synthesis: A knowledge synthesis chapter. Canadian Institutes of Health Research.
 

Higgins, J.P.T. & Green, S. (Eds.). (2011). Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 [updated March 2011]. The Cochrane Collaboration. Available from www.handbook.cochrane.org.

Institute of Medicine. (2011). Finding what works in health care: standards for systematic reviews. Washington, DC: The National Academies Press.

Kastner, M., Antony, J., Soobiah, C., Straus, S. E., & Tricco, A. C. (2016). Conceptual recommendations for selecting the most appropriate knowledge synthesis method to answer research questions related to complex evidence. Journal of Clinical Epidemiology, 73, 43-49.

Koffel, J. B. (2015). Use of recommended search strategies in systematic reviews and the impact of librarian involvement: A cross-sectional survey of recent authors. PLoS ONE, 10(5), 1–13. https://doi.org/10.1371/journal.pone.0125931

Mays, N., Roberts, E., & Popay, J. (2001). Synthesising research evidence. Studying the Organisation and Delivery of Health Services: Research Methods, 188-220.

McGowan, J., & Sampson, M. (2005). Systematic reviews need systematic searchers. Journal of the Medical Library Association, 93(1), 74.

Meert, D., Torabi, N., & Costella, J. (2016). Impact of librarians on reporting of the literature searching component of pediatric systematic reviews. Journal of the Medical Library Association : JMLA, 104(4), 267–277. https://doi.org/10.3163/1536-5050.104.4.004

Pearson, A., White, H., Bath-Hextall, F., Apostolo, J., Salmond, S., & Kirkpatrick, P. (2014). Methodology for JBI mixed methods systematic reviews. The Joanna Briggs Institute Reviewers’ Manual.
 
Peters, M. D., Godfrey, C. M., Khalil, H., McInerney, P., Parker, D., & Soares, C. B. (2015). Guidance for conducting systematic scoping reviews. International journal of evidence-based healthcare, 13(3), 141-146.

Peters, M. D, Godfrey, C. M., McInerney, P., Soares, C., Hanan, K., & Parker, D. (2015). The Joanna Briggs Institute Reviewers' Manual 2015: Methodology for JBI Scoping Reviews.


Petticrew, M. (2001). Systematic reviews from astronomy to zoology: myths and misconceptions. BMJ: British Medical Journal, 322(7278), 98.

Rethlefsen, M. L., Farrell, A. M., Osterhaus Trzasko, L. C., & Brigham, T. J. (2015). Librarian co-authors correlated with higher quality reported search strategies in general internal medicine systematic reviews. Journal of Clinical Epidemiology, 68(6), 617–626. https://doi.org/10.1016/j.jclinepi.2014.11.025

Saleh, A. A., Ratajeski, M. A., & Bertolet, M. (2014). Grey literature searching for health sciences systematic reviews: a prospective study of time spent and resources utilized. Evidence Based Library and Information Practice, 9(3), 28-50.

Tricco, A. C., Lillie, E., Zarin, W., O’Brien, K., Colquhoun, H., Kastner, M., ... & Kenny, M. (2016). A scoping review on the conduct and reporting of scoping reviews. BMC medical research methodology, 16(1), 1.
 

Uman, L. S. (2011). Systematic reviews and meta-analyses. Journal of the Canadian Academy of Child and Adolescent Psychiatry, 20(1), 57.