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.
|METHOD||Systematically search for, appraise, and synthesize research evidence||Statistically combine the results of quantitative studies to provide a more precise effect of the results|
|FORMAT||Results are typically narrative, may have tabular component||Results are graphical and tabular with narrative commentary|
|CONTENT||Analyzes what is known; recommendations for practice. Identifies what remains unknown; uncertainty around findings, recommendations for future research||Numerical analysis of measure of effect assuming absence of heterogeneity.|
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:
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.
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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.
This article was originally part of the HSL News series Understanding review types. For more information about this series, read the series’ introduction.