An umbrella review is a review of reviews. It compiles all the evidence from existing reviews on a topic to give a high level overview.
An umbrella review is commonly conducted when there are multiple competing interventions for a condition. An overview of reviews about each of these interventions can be useful in determining how to best translate the evidence into practice.
Like many other reviews, the aim of an umbrella study is to determine what is known on a topic, what remains unknown, and recommendations are made for what requires further research.
While searching for literature to include in an umbrella review, reviews (of varying types) are identified, but no primary studies are included. The quality assessment of these studies can be in two parts:
1) an assessment of the methodology of the review and (or)
2) of the component primary studies methodologies that were included.
Information about included studies in an umbrella review are often displayed in a table. A narrative commentary explains the results and key points about each of the reviews and how the evidence is interpreted to guide practice.
Librarians are involved most heavily with identifying reviews for inclusion in the umbrella review, where expert search skills play a crucial role. Searching is a critical part of conducting reviews and errors made in the search process can result in biased or incomplete evidence.
Researchers seeking help with umbrella 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.
This article is a part of the HSL News series Understanding review types. For more information about this series, read the series’ introduction.
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