TTi conducted a systematic review, designed to evaluate the risk of ulcerative colitis with isotretinoin use, in accordance with best practices. A thorough review of the evidence base was undertaken, and epidemiological studies examining the safety of isotretinoin that specifically reported on ulcerative colitis were carefully identified. Data was abstracted using standardized tools and evaluated for pooling. A rigorous meta-analysis was performed, including various sensitivity analyses. TTi also provided technical and statistical support on a broad range of topics, including epidemiological methods, methods for evidence synthesis, power and sample size calculations, and developed memos, reports and presentations for various lay audiences. TTi is now in the process of developing a peer-reviewed manuscript from the results of the meta-analysis.