Clinical features and natural history of ulcerative colitis in Korea

Background: The clinical characteristics of ulcerative colitis (UC) in Asian populations have not been well characterized. We therefore investigated the clinical features and natural history of UC in Korea. Methods: We retrospectively analyzed 304 Korean patients with UC first diagnosed at the Asan Medical Center between June 1989 and August 2005. Results: The male-to-female ratio of the patients was 0.94:1, and their median age at diagnosis was 40.0 years (range, 12-72 years). At diagnosis, proctitis was noted in 134 patients (44.1%), left-sided colitis in 69 patients (22.7%), and extensive colitis in 101 patients (33.2%). Disease activity at diagnosis was mild in 149 patients (49.0%), moderate in 125 patients (41.1%), and severe in 26 patients (8.6%). In addition, 4 asymptomatic patients (1.3%) were detected as a result of a screening colonoscopy. Clinical remission after the first attack was documented in 97.4% of patients. The cumulative relapse rate after 1, 5, and 10 years was 30.2%, 72.0%, and 88.4%, respectively. The cumulative risk of proximal extension in patients with proctitis or left-sided colitis was 33.0% after 5 years and 44.5% after 10 years. The cumulative probability of colectomy was 2.0% after 1 year, 2.8% after 3 years, and 3.3% after 5 to 15 years. The cumulative survival rate after 1, 5, and 10 years was 100%, 99.4%, and 97.4%, respectively. Conclusions: The clinical features of Korean UC patients at diagnosis are similar to those of Westerners. However, UC in Koreans may have a milder course than in Westerners, as indicated by the lower rate of colectomy among Koreans.