Background The Institute of Medicine recommended standards for systematic review, but some guideline developers find the standards time and resource intensive. Rapid reviews are becoming a popular method to appraise and summarise evidence. But what are rapid reviews and do they replace or rely on systematic review?

Objectives To clarify major differences between rapid reviews and systematic reviews, especially aims, methods and uses for guidelines and policy.

Methods Overview of reviews and examination of organisational policies for rapid review focusing on reasons users request rapid review, methods used to produce them, and the uses of those syntheses.

Results There is no standards methodology for producing rapid review, nor is there consistency in intended use. Some organisations rely on systematic reviews to produce rapid review, while others incorporate short cuts in systematic review process. In addition to faster production, some users of rapid review are seeking product that is more clinically relevant and ready for implementation.

Discussion There are many ways to speed up systematic review, some at risk of introducing bias. Without clear understanding of the reasons users request rapid review and their expectations for the evidence product, simply speeding the time frame may not address all of user needs for evidence they can implement quickly.

Implications for Guideline Developers/Users Until there is consensus on what the label rapid review describes, users will need to identify their own minimal standards and evaluate adherence. Developers should be clear about user expectations for using the evidence.