PURPOSE: The ideal treatment for chronic and recurrent colonic diverticular disease (crDD) remains unresolved, partly due to lacking evidence regarding surgical safety. This study evaluated 90-day reoperation and mortality rates following elective surgery for crDD and explored predictors for reoperation and mortality. METHODS: This national cohort study included all patients with crDD undergoing elective colonic resection or stoma formation in Denmark from 1996-2021. Outcomes were the 90-day cumulative incidence proportion (CIP) of reoperation and mortality, and predictors were explored in Cox proportional hazard models. RESULTS: Among 35,174 patients with crDD, 3,584 (10%) underwent elective surgery. The 90-day reoperation rate was 18.0%
mortality was 1.6%. During the 25-year period, the reoperation rate declined 30%, from 19.5% to 13.8%, and mortality declined 74%, from 2.7% to 0.7%. Among 2,942 patients with colonic resection and no stoma formation, the reoperation rate due to anastomotic leak was 3.0% overall and 0.9% in the most recent years. Mortality was 18 times higher in patients aged ≥ 80 years versus those aged <
60 years (CIP 8.0% versus 0.4%). The reoperation rate was increased in patients with ≥ 4 hospital contacts or ≥ 3 admissions compared to patients with fewer contacts, while mortality was not associated with the number of hospital contacts before surgery. CONCLUSION: Elective surgery in crDD was safe with careful patient selection. The risk of reoperation due to anastomotic leak was very low. Patients with most hospital contacts had an increased reoperation rate, supporting consideration for elective surgery early in patients with disabling diverticular disease.