The Pandora's Box of Evidence Synthesis and the case for a living Evidence Synthesis Taxonomy.

Abstract

Have we, as an evidence-based health community, opened the Pandora's box of evidence synthesis? There now exists a plethora of overlapping evidence synthesis approaches and duplicate, redundant and poor-quality reviews.1-4 After years of advocating for the need for systematic reviews of the evidence, there is a risk that this message been disseminated too widely and has been misinterpreted in this process. We have reached a point where in some fields more reviews exist than clinical trials, where same topic reviews are being conducted in parallel, and evidence syntheses possess limited utility for decision-making because of their poor quality or poor reporting.To paraphrase the late Douglas Altman,5 it is possible we are now at a stage where we need less reviews, better reviews and reviews done for the right reason - as opposed to the current state of mass production (approximately 80 reviews per day)6.