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Gerstein Science Information Centre

Knowledge syntheses: Systematic & Scoping Reviews, and other review types

Definition

Booth (2016) states that "essentially an umbrella review is a cluster of existing systematic reviews on a shared topic" (p. 37). Umbrella reviews are also known as an overview of reviews. According to Grant & Booth (2009) umbrella reviews are "overarching reviews" that "agreggrat[e] findings from several reviews that address specific questions" (p. 103). Moreover, "each umbrella review focuses on a broad condition or problem for which there are two or more potential interventions and highlights reviews that address these potential interventions and their results" (Grant & Booth, 2009, p. 103).

When is an Umbrella Review methodology appropriate?

When to Use It: Umbrella reviews are best suited for topics which are already addressed in systematic and/or meta-analyses. Grant & Booth (2009) state that umbrella reviews are useful for combining the results of various reviews on a certain question. Booth (2016) adds that:

"Typically, the broad topic area will have been “split” into focused populations and/or interventions. The umbrella review seeks to impose an overall coherence by lumping these precise reviews together. Umbrella reviews are particularly valuable within health technology assessments that aim to consider all management options and yet may commission separate reviews of an individual treatment with specific outcomes" (p. 37).

Becker et al. (n.d) add that as there may be many possible interventions for a specific condition, it is beneficial for decision-makers to save time reviewing individual reviews and rather read an umbrella or overview of reviews that cover all possible interventions. An umbrella review can point at reviews that address different types of interventions. 

Elements of an Umbrella Review

The following characteristics, strengths and challenges are derived from Becker et al. (n.d), Booth (2016) and Grant & Booth (2009)

Characteristics:

  • An umbrella review is essentially a single document that includes evidence from a variety of Cochrane reviews 
  • An umbrella review can only be accomplished if the intervention of interest has already been discussed in a review

Strengths:

  • Provides a useful and quick overview of reviews for a particular topic as well as all the relevant reviews on that topic
  • Grant & Booth (2009) state that umbrella reviews "are a response, and potential solution, to the perennial dilemma reviewers face regarding 'lumping' versus 'splitting', i.e. whether the needs of a particular field or area are best addressed by a broad review...or by a succession of focused reviews" (p. 103)
  • They "build upon an area that is well-covered by existing systematic reviews by synthesizing the evidence from all relevant reviews to provide a single report which summarizes the current state of knowledge on the topic" (Booth, 2016, p. 37)
  • Umbrella reviews can "bring together many treatment comparisons for the management of the same disease or condition" (Booth, 2016, p. 37)

Weaknesses:

  • An umbrella review cannot be completed without pre-existing reviews
  • Limitations involve "the amount, quality and comprehensiveness of available information in the primary studies" (Booth, 2016, p. 37)

Methods and Guidance

The following resource provides further support on conducting an umbrella review:

METHODS & CONDUCT

Joanna Briggs Institute (JBI) Reviewer's Manual. Chapter 10: Umbrella Reviews: An extensive and detailed outline within the JBI Reviewer's Manual on how to properly conduct an umbrella review.

REPORTING

Methodology for JBI umbrella reviews: Comprehensive paper outlining the methodology in conducting umbrella reviews, from the Joanna Briggs Institute. 

SUPPLEMENTARY RESOURCES

Check out the supplementary resources page for additional information, including articles, on umbrella reviews.