P246 Long-term prognosis of ulcerative colitis and its temporal changes between 1986 and 2015 in a population-based cohort in the Songpa-Kangdong district of Seoul, Korea

Abstract Background No population-based study has evaluated the natural course of ulcerative colitis (UC) over three decades in non-Caucasians. We aimed to assess the long-term natural course of Korean patients with UC in a population-based cohort. Methods This Korean population-based SK-IBD cohort included all patients (N = 1013) newly diagnosed with UC during 1986–2015. Disease outcomes and their predictors were evaluated. Results During the median follow-up of 105 months, the overall use of systemic corticosteroids, thiopurines, and anti-tumour necrosis factor (TNF) agents was 40.8%, 13.9%, and 6.5%, respectively. Over time, the cumulative risk of commencing corticosteroids decreased, whereas that of commencing thiopurines and anti-TNF agents increased. During follow-up, 28.7% of 778 patients with proctitis or left-sided colitis at diagnosis experienced proximal disease extension. A total of 28 patients (2.8%) underwent colectomy, demonstrating cumulative risks of colectomy at 1, 5, 10, 20, and 30 years after diagnosis of 1.0%, 1.9%, 2.2%, 5.1%, and 6.4%, respectively. Multivariate Cox regression analysis revealed that extensive colitis at diagnosis (hazard ratio [HR] 8.249, 95% confidence interval [CI] 2.394–28.430), ever use of corticosteroids (HR 6.437, 95% CI 1.440–28.773), and diagnosis in the anti-TNF era (HR 0.224, 95% CI 0.057–0.886) were independent predictors of colectomy. The standardised mortality ratio in UC patients was 0.725 (95% CI 0.508–1.004). Conclusion Korean UC patients may have a better clinical course than Western patients, as indicated by a lower colectomy rate. The overall colectomy rate has continued to decrease over the past three decades.