The COSMID trial is a study to see if surgery or medicine is better for people with diverticulitis. Diverticulitis is when small pouches in the colon get inflamed. The trial compares elective colectomy (a surgery to remove part of the colon) with best medical management. Best medical management includes treatments like fiber, antibiotics, and probiotics to help with symptoms. The study wants to know which option helps improve quality of life (QoL) the most. People can join the study if they have had at least one episode of diverticulitis confirmed by a CT scan, and they are over 18 years old. People with certain health issues, like a history of surgery for diverticulitis or who are pregnant, can't join.

• The study is conducted at multiple sites and participants are randomly assigned a treatment.
• Participants can choose to share their outcomes without random treatment assignment.
• The study focuses on improving QoL for those with diverticulitis.