S1906 Neglected Differences: A Meta-Epidemiologic Review of Sex-Disaggregated Outcome Reporting in Ulcerative Colitis Drug Trials

Introduction: Sex-based differences shape disease presentation, drug metabolism, and treatment outcomes in ulcerative colitis (UC). While NIH and other regulatory bodies mandate inclusion of sex as a biological variable, clinical trials rarely analyze or report efficacy or safety outcomes by sex. This oversight undermines equitable care and hampers the translation of trial findings into personalized therapy. To evaluate the frequency and quality of sex-disaggregated outcome reporting in UC drug trials over the past decade and identify factors linked to improved reporting practices. Methods: We performed a meta-epidemiologic review of UC trials registered on ClinicalTrials.gov from January 1, 2010, to present. Trials were eligible if they included adults (≥18 years), were marked as completed, posted results, and enrolled ≥10 participants. Among 461 inflammatory bowel disease trials screened, 167 UC-specific trials met inclusion criteria. Each was assessed for sex reporting, sex-disaggregated outcome data, and subgroup analysis. Trial characteristics—phase, sponsor type, site geography—were also recorded. Results: Of 167 UC trials, 92.4% (n = 154) reported the sex of enrolled participants. However, only 6 trials (1.4%) provided sex-disaggregated efficacy or safety outcomes. None included pre-specified subgroup analyses by sex. Trials with larger sample sizes, industry sponsorship, and international recruitment were slightly more likely to report sex data, but these traits did not consistently translate into stratified analysis. Discussions of underlying biological or sociocultural mechanisms for sex differences were rare. Conclusion: Despite near-universal reporting of participant sex, UC drug trials overwhelmingly fail to analyze or disclose sex-specific outcomes. This disconnect between policy and practice represents a significant barrier to sex-informed care and precision medicine. Adoption of standardized sex-disaggregated reporting is essential for equitable, evidence-based treatment strategies in UC.