Explicit reporting of absolute measures is important to ensure treatment effects are correctly interpreted. We examined the extent to which authors report absolute effects for patient-important outcomes in abstracts of systematic review. We searched OVID Medline and Cochrane Database of Systematic Reviews to identify eligible systematic reviews published in the year 2010. Citations were stratified into Cochrane and non-Cochrane reviews, with repeated random sampling in a 1:1 ratio. Paired reviewers screened articles, and recorded abstract characteristics including reporting of effect measures for the most patient-important outcomes of benefit and harm. We included 96 Cochrane and 94 non-Cochrane reviews. While 117 (77.5%) relative measures were reported in abstracts for outcomes of benefit, only 34 (22.5%) absolute measures were reported. Similarly, for outcomes of harm, 41 (87.2%) relative measures were provided in abstracts, compared to only 6 (12.8%) absolute measures. Eighteen (9.5%) abstracts reported both absolute and relative measures for outcomes of benefit, while only two (1.1%) reported both measures for outcomes of harm. Results were similar between Cochrane and non-Cochrane reviews. Systematic review abstracts seldom report measures of absolute effect. Journal editors should insist that authors report both relative and absolute effects for patient-important outcomes
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