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Systematic Reviews & Other Review Types

This guide will help you get started with your next systematic review, scoping review, or other review types.

Other names for an Overview of Reviews

Systematic Review of Systematic Reviews, Umbrella Review, Review of Reviews, Summary of Systematic Reviews, Synthesis of Reviews, Review of Systematic Reviews, Review of Reviews, Review of Meta-analyses, Meta-review, Systematic Meta-review, Meta-Meta-analysis

What is an Overview of Reviews?

It is a systematic review of systematic reviews.  "The intent of this kind of review is to include systematic reviews or meta-analyses as the main study type and thus examine only the highest level of evidence." 

"The aim is not to repeat the searches, assess study eligibility, and assess risk of bias from included studies but rather to provide an overall picture of findings."

(Source: Blackwood D (2016))

Overviews of Reviews are best designed for:

  • Synthesizing and combining relevant data from existing systematic reviews or meta-analyses to make better decisions.
  • To provide clinical decision makers with the evidence they need when there are too many systematic reviews for them to keep up with for an intervention.
  • When there needs to be a rapid evidence synthesis for decision-makers but you need higher quality evidence due to limitations of the rapid review methodology.

What is an Overview of Reviews? Outline of Stages

Timeframe: Approximately 12 months or less.   *Varies beyond the type of review. Depends on many factors such as but not limited to: resources available, the quantity and quality of the literature, and the expertise or experience of reviewers" (Grant et al. 2009)

Question: A broad or narrow PICO of 1 or more interventions.

Is your review question a complex intervention? Learn more here

Sources and searches: Only locating the highest level of evidence of published or unpublished:

  1. Systematic Reviews or
  2. Meta-analyses

The aim is not to identify any new studies.  Cochrane Overviews of Reviews only identify Cochrane reviews unless it is necessary to include non-Cochrane reviews.  Is likely to limit the search from 1990 to current since there were few research syntheses published prior.

See our Systematic Review Search Service for help conducting the search!

Selection: Based upon clear inclusion/exclusion criteria and outcome measures defined a priori. 

Appraisal: Critical Appraisal of systematic reviews done by at least two independent reviewers using the appropriate tool.  Overall grade assessment of the evidence, Cochrane starting to include GRADE. 

Synthesis: May need to alter the meta-analyses in the included reviews or re-synthesis the data while extracting and combining the relevant data.  A final 'Summary of Evidence' table should be present.

Limitations of an Overview of Reviews

  • It is often mistaken as just a summary of reviews but it must include the re-synthesis of data.
  • Sometimes confused with being as quick as a rapid review, but an Overview of Reviews doesn't omit steps of the traditional systematic review process like a rapid review.  Overviews of Reviews also do not include other study types other than systematic reviews and meta-analyses.
  • Requires a systematic review expert to critically appraise systematic reviews.

For additional help

Systematic Review Service:

The health sciences library Chat with a Librarian service is available at Many of our librarians are available to provide systematic review education. Or you may reach the Team Lead, Stephanie Roth: Email Phone (215) 707-9469