Reporting of adverse events in systematic reviews can be improved: survey results

ObjectiveTo assess how information about adverse events is included in systematic reviews.Study Design and SettingWe included all new Cochrane reviews published in the Cochrane Database of Systematic Reviews (CDSRs) and all new reviews (2003–2004) in the Database of Abstracts of Reviews of Effects (DAREs) in Issue 1 2005 of The Cochrane Library.ResultsMore than half of Cochrane (44/78) and DARE (46/79) reviews assessed drug interventions. The rest assessed surgery (Cochrane [12]; DARE [10]), psychosocial, educational, or physiotherapy interventions (22; 23). Seventy-six percent (59/78) of Cochrane reviews mentioned adverse events as an outcome compared with 48% (38/79) of DARE reviews. Most reviews mentioning adverse events were of drug interventions (Cochrane [41/59]; DARE reviews [29/38]). Considering reviews that mentioned adverse events, 95% (56/59) of Cochrane reviews included only randomized trials and 73% (43/59) included an analysis of adverse events. For 10 Cochrane reviews, adverse events had not been reported by the included trials. In contrast, 58% (22/38) of DARE reviews mentioning adverse events included only randomized trials, the rest included both randomized and nonrandomized studies.ConclusionsMost Cochrane reviews of drug interventions considered adverse events. This was not the case for DARE reviews and for Cochrane reviews of nondrug interventions. This could be improved.