6.20 Rapid Evidence Assessment (REA) is a pared down version of systematic review, employing the same general principles but in a lighter-touch manner to enable reviews to be undertaken more quickly. REAs collate descriptive outlines of the available evidence on a topic, critically appraise them, sift out studies of poor quality, and provide an overview of what the evidence says and what is missing from it. They are based on fairly comprehensive electronic searches of appropriate databases, and some searching of print materials, but not the exhaustive database searching, hand searching of journals and textbooks, or searches of the grey literature that go into systematic reviews.
6.21 Rapid Evidence Assessments carry a caveat that their conclusions may be subject to revision if more systematic and comprehensive review of the evidence is subsequently completed. This is consistent with the important principle that systematic reviews are only as good as their most recent updating and revision allows.