Long-term follow-up of ulcerative colitis in the Chinese population

OBJECTIVES: The incidence of ulcerative colitis (UC) in Asia is increasing but reports on its long-term course are few. We set out determine the incidence, prevalence, and survival rate of UC in the Chinese population and phenotypic stability by longitudinal follow-up. METHODS: A cohort of Chinese UC patients were followed up in a tertiary referral center in Hong Kong between 1985 and 2006. Clinical data were prospectively collected since 2001. Population statistics were obtained from the Census and Statistics Department of Hong Kong for the calculation of age-specific incidence, prevalence, and survival. The disease phenotypes at diagnosis and upon follow-up were documented. RESULTS: A total of 172 patients (51.7% men) with a median age at diagnosis of 37.0 years (range: 12.0-85.0) were included. The cohort was observed for a total of 1,393 person-years with a median follow-up duration of 7.0 years (range: 0.5-22.0). The age-standardized incidence and prevalence rates of UC per 100,000 were 2.1 (95% confidence interval, CI: 1.1-3.7) and 26.5 (95% CI: 22.6-30.9), respectively, in 2006. The 10-year cumulative rate of proximal extension was 23.8%. Only one patient developed colorectal cancer during the observation period. The cumulative colectomy rates were 2.4% and 7.6% at 1 and 10 years of follow-up. Overall survival was similar to that expected (P=0.07). CONCLUSIONS: The incidence of UC has increased sixfold in the past two decades in Hong Kong. The complication, colorectal cancer, and colectomy rates are low in Chinese patients but increase with duration of illness.