The Comparison of Surgery and Medicine on the Impact of Diverticulitis (COSMID) trial is a randomized trial of elective colectomy vs. best medical management for patients with diverticulitis that limits their quality of life. Funded by the Patient-Centered Outcome Research Institute, the results of the COSMID trial are expected to establish an evidence-based approach to the care of millions of patients per year in the United States and help people impacted by this common condition make more informed treatment decisions.