Natural history of bleeding risk in colonic diverticulosis patients: a long‐term colonoscopy‐based cohort study

Summary Background The natural history of bleeding risk from colonic diverticulosis remains unclear. Aim To identify the incidence of bleeding in colonic diverticulosis patients and associated risk factors. Methods A cohort of 1514 patients with colonoscopy‐confirmed asymptomatic diverticulosis was selected between 2001 and 2013. Age, sex and location of colonic diverticulosis (right or left side, or bilateral) were assessed. The endpoint was a bleeding event, and data were censored at the time of last colonoscopy. The cumulative and overall incidences of bleeding were estimated using the Kaplan–Meier and person‐years methods. The Cox proportional hazards model was used to estimate age‐ and sex‐adjusted hazard ratios (aHRs). Results The median follow‐up period was 46 months. Bleeding events occurred in 35 patients, and the median time‐to‐event interval was 50 months. Kaplan–Meier analysis showed that the cumulative incidence of diverticular bleeding was 0.21% at 12 months, 2.2% at 60 months and 9.5% at 120 months. By the person‐years method, the overall incidence rate of bleeding was 0.46 per 1000 patient‐years. On multivariate analysis, age ≥70 (aHR. 3.7) and bilateral diverticulosis (aHR, 2.4) were significant risk factors for bleeding. Conclusions This long‐term follow‐up study demonstrated that the cumulative incidence of bleeding from diverticulosis was approximately 2% at 5 years and 10% at 10 years, and the overall incidence was 0.46 per 1000 patient‐years. Bilateral diverticulosis increased the risk of bleeding.