A retrospective comparison of systematic reviews with same-topic rapid reviews

To compare rapid reviews (RRs) to same-topic systematic reviews (SRs) for methods, studies included, and conclusions.

A retrospective comparison of studies comparing RRs and SRs by searching four scoping reviews published between 2007 and 2016. Reports were included if literature searches were conducted within 24 months of each other and had common research questions. Reviews were compared for duration, studies included, population, intervention, comparisons, outcomes, study designs, quality, methods, and conclusions.

Six studies containing 16 review pairs were included, covering nine topics. Overall, RRs used abbreviated methods more often: no search of grey literature, employing one reviewer to screen studies, engaging fewer experts, including fewer studies, and providing shorter reports, with poorer reporting quality and faster completion. Reviews reported similar conclusions, with two exceptions: one SR did not include a key study; separately, two RRs failed to highlight an association with early mortality identified by the SR. RRs tended to provide less detail and fewer considerations.

RRs used several methodological shortcuts compared with SRs on the same topic. It was challenging to discern methodological differences because of retrospective assessment and substantial nonreporting, particularly for RRs.