Background: Women may be under-represented in medical research (including trials), although this is debated. If true, this has a number of implications: a) trials are generally associated with better quality care and outcomes, and thus unequal participation is inequitable; and b) it may not be appropriate to generalise results of trials conducted in one gender group to practice in another. We might anticipate differences between sexes in conditions where women present with different symptoms, respond to treatment differently, adhere to treatment differently, or are treated differently by health staff. In producing systematic reviews, the Collaboration is well placed to inform this debate by considering gender in trial participants and outcomes by gender. This study examines whether information on gender is routinely extracted from trial data by reviewers, and whether the analysis of effects is presented by gender.

Methods: Within each Collaborative Review Group concerned with health problems that affect both women and men, we selected a random selection of reviews. For each review, we examined the details of the included trials. We recorded whether the gender of participants in the trial is reported, and whether men or women predominated in the study population. We also examined whether reviewers systematically sought, and reported on, gender analysis in each trial. Finally, we examined whether meta-analyses for subgroup analysis, or meta-regression, were presented by gender. Results and discussion: We will present the results of the analysis, and discuss the implications for clinicians, reviewers, editors, funders and people planning clinical trials.