Understanding Review Types: Systematic / Meta-analysis Reviews

A systematic review or meta-analysis is a study of studies. These reviews aim to collect all existing evidence to address a specific research question. The criteria used to select included evidence is pre-defined and responds precisely to the research question. Explicit methods to minimize bias and increase transparency are used to produce reliable synthesis of information. The purpose of this synthesized information is to create strong evidence to inform clinical decision-making, policy and research.

It is important to note that all meta-analyses are systematic reviews, but not all systematic reviews are meta-analyses. There are six steps to consider:

1. Plan – Frame research question, determine inclusion and exclusion criteria for studies, create project management outline including deadlines and responsibilities, and develop protocol.
2. Identify – Determine search terms and databases to search, retrieve studies and document findings.
3. Evaluate – Screen, select, sort, and appraise studies.
4. Collect & Code – Determine forms, code selected studies, and synthesize data extracted.
5. Explain – Analyze findings and put them into context.
6. Summarize – Write up the report.

These steps usually takes about 12 months, with a minimum of 6 months recommended. Systematic reviews and meta-analyses are undertaken by a research team rather than individual researchers to facilitate expedited review of studies and reduce researcher bias.

Librarians are involved most heavily with step two: the “Identify” step, where expert search skills play a crucial role. Searching is a critical part of conducting systematic reviews and errors made in the search process can result in biased or incomplete evidence. Researchers seeking help with systematic reviews can help their librarians by having a general sense of the literature in the field (see our previous post on literature reviews), including knowledge of key works and specialized terminology.

For more information about systematic reviews, see our Systematic Review Resources guide. 

References

Grant, M. & Booth, A. (2009). A typology of reviews: an analysis of 14 review types and associated methodologies. Health Information and Libraries Journal, 26(2), 91-108. DOI: 10.1111/j.1471-1842.2009.00848.x

Higgins JPT, Green S (editors). Cochrane Handbook for Systematic Reviews of Interventions Version 6 [updated Sept 2018]. The Cochrane Collaboration, 2018. Available from http://handbook.cochrane.org/

Other readings

Møller AM and Myles PS. What makes a good systematic review and meta-analysis?, BJA: British Journal of Anaesthesia. 2016. 117(4): 428–430.

Munn Z et al. Systematic review or scoping review? Guidance for authors when choosing between a systematic or scoping review approach.  BMC Medical Research Methodology. 2018;18:143.

Aromataris E, Munn Z (Editors). Joanna Briggs Institute Reviewer's Manual. The Joanna Briggs Institute, 2017.

Higgins JPT, Green S (editors). Cochrane Handbook for Systematic Reviews of Interventions. The Cochrane Collaboration, 2011.

Liberati A et al. The PRISMA Statement for Reporting Systematic Reviews and Meta-Analyses of Studies That Evaluate Health Care Interventions: Explanation and Elaboration. PLoS Med. 2009. 6(7): e1000100.

Cochrane Living Systematic Reviews-Interim Guidance for Pilots (version 0.3). 21 April 2017

This article was originally part of the HSL News series Understanding review types. For more information about this series, read the series’ introduction.

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