No Single Definition of a Rapid Review Exists, but Several Common Themes Emerge

"The only consensus around [a rapid review] definition," write Hamel and colleagues in a review published in the January 2021 issue of the Journal of Clinical Epidemiology, "is that a formal definition does not exist."

In their new review, Hamel et al. sifted through 216 rapid reviews and 90 methodological articles published between 2017 and 2019 to better understand the existing definitions and use of the term "rapid review," identifying eight common themes among them all.

The figure below from the publication shows the relative usage of these themes throughout the relevant identified articles.

In summary of all definitions examined in the review, the authors suggest the following broad definition of a rapid review: "a form of knowledge synthesis that accelerates the process of conducting a traditional systematic review through streamlining or omitting a variety of methods to produce evidence in a resource-efficient manner."

To complicate matters further, Hamel and colleagues also found that reviews meeting these general criteria may not always go by the term "rapid." For instance, the term "restricted review" fits many of these same parameters, but is not necessarily defined by the amount of time from inception to publication. However, the lack of an as-yet agreed-upon definition of a "rapid review" may ultimately hamper authors and potential end-users of these products, as the accepted legitimacy of such reviews may depend upon a common understanding of their standards and methodological frameworks. In addition, the range of rigor and specific protocols continues to vary widely between products labeled as "rapid reviews." Until there is a broader consensus of the definition of a rapid review and what, exactly, it entails, this working definition and associated themes provide insight into the current state of the art.

Check out our related post on the two-week systematic review here.

Hamel C, Michaud A, Thuku M, Skidmore B, Stevens A, Nussbaumer-Streit B, and Garritty C. (2020). Defining rapid reviews: A systematic scoping review and thematic analysis of definitions and defining characteristics of rapid reviews. J Clin Epidemiol 129: 74-85.

Manuscript available from the publisher's website here.