"Evidence synthesis uses formal, explicit, and rigorous methods to bring together the findings of research already completed, to provide an account of the totality of what is known from that pre-existing research." 1
A systematic review is a type of evidence synthesis that evaluates the "evidence on a clearly formulated question that uses systematic and explicit methods to identify, select, and critically appraise relevant primary research, and to extract and analyze data from the studies that are included in the review." The methods used must be reproducible and transparent. 2
Evidence synthesis requires:
1. Gough D, Davies P, Jamtvedt G, et al. Evidence Synthesis International (ESI): Position Statement. Systematic Reviews. 2020;9(1):155. doi:10.1186/s13643-020-01415-5
2. Wright RW, Brand RA, Dunn W, Spindler KP. How to write a systematic review. Clin Orthop Relat Res. 2007;455:23-29. doi:10.1097/BLO.0b013e31802c9098
Although systematic reviews are the most recognized type of evidence synthesis, there are many other types of evidence reviews. Elements like the size of your team, timeline for the project, and specificity of your research question can help determine the type of review that best serves your needs.
Literature review/ Narrative Review |
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Scoping Review |
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Systematic Review |
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Rapid Review |
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Umbrella review |
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Source: Grant MJ, Booth A. A typology of reviews: an analysis of 14 review types and associated methodologies. Health Information & Libraries Journal. 2009;26(2):91-108. doi:10.1111/j.1471-1842.2009.00848.x
1. Develop a Research Topic
2. Define Inclusion and Exclusion Criteria
3. Search the Literature
More details are provided in Literature Search
4. Select Studies
5. Assess study quality
6. Extract Data
7. Analyze and Present Results
8. Interpret Results
Reviewers should comment on:
9. Update the Review as Needed
New research findings can quickly make Evidence Synthesis reviews out of date.