Many reports of randomised trials still don't begin or end with a systematic review of the relevant evidence
Clarke M., Hopewell S.
Background: Existing evidence should provide ethical, scientific and environmental justification for new randomised trials and users of the findings of these trials need to see them in the context of similar trials. Since 1997, audits have been done of reports of randomised trials in Annals of Internal Medicine, BMJ, JAMA, Lancet, and New England Journal of Medicine to see if results are placed in context in the Discussion section of the report and, since 2005, to see if systematic reviews are used in the Introduction section. Methods: We handsearched each May 2012 issue of these five journals to identify reports of randomised trials. Introduction and Discussion sections were categorised on the basis of their use of systematic reviews. Results: Thirty-five reports of randomised trials were included. Considering the Introduction sections: 5 were said to be the first trial, 1 used an updated systematic review in the design, 13 discussed previous systematic reviews, 10 mentioned other trials, and 6 didn't mention other trials or claim to be the first. Considering the Discussion sections: 2 were said to be the first trial, 2 contained a systematic review integrating the new trial, 11 mentioned a systematic review, and 20 made no apparent systematic attempt to place findings in full context. There was variability across the journals, with reports in the Lancet making notably more use of systematic reviews. Conclusions: Many trials still do not use systematic reviews in their design and reporting.