143,144 However, definitions of clinical relapse and measurements of disease severity vary between studies. In studies from across Asia, most patients with UC had a milder disease course,35,70 with more frequent relapsing

disease course rather than continuous active disease.56,80 A study from South Korea reported cumulative relapse rates after 1, 5, and 10 years to be 30%, 72%, and 88%, respectively.84 In a Malaysian study, no significant differences were seen in the severity of disease between different IBD patients of different ethnicities.56 A recent study from Korea found that for patients diagnosed at age 40 years or less disease was more severe at presentation than those diagnosed at age greater than 40 years. Cumulative relapse ZD1839 and surgical rates were not different.145 In a separate Korean study146

comparing 39 patients aged 18–44, to 34 patients aged 45–85, age less than 45 was found to be an independent predictor of relapse in UC, similar to data from a previous Western study.147 Colectomy.  Studies from the West have reported cumulative colectomy rates at one year of 6–11%, 5 years of 20% and 10 years of 24–28%.90,143,148 Colectomy rates are lower in Asian BAY 57-1293 in vivo UC patients, with rates at one year 2.0–4.1%;84,149 5 years, 5.9%;56 and 10 years, 7.6–15.6%.26,56 It is unclear whether these lower colectomy rates are related to a milder disease presentation and course in Asian subjects, variations in disease management in Asia, or different physician and patient thresholds for colectomy. A recent Japanese study identified early factors predicting colectomy in patients who did not undergo colectomy within their first month of diagnosis. These included moderate or severe disease at diagnosis, as assessed using Truelove and Witt criteria, as well as low hemoglobin and albumin 4 weeks after first induction therapy.138 Colorectal cancer.  Colorectal cancer (CRC) is a known complication of long term UC and

screening is recommended after 8–10 years of the disease.150 The overall prevalence of CRC associated with UC has been reported at 3–5% MCE in the West151 and 0.0–2.2% in Asia.26,55,70,81,84,152,153 In many Asian studies cumulative incidence rates were not reported and there was a relatively short duration of follow-up. In a meta-analysis of studies from around the world, excluding Asian countries, the cumulative risk of CRC-associated with UC was reported to be 1.6%, 8.3% and 18.4% at 10, 20 and 30 years.154 CRC rates are comparatively lower in UC patients in India:82,155 0%, 1.0–2.3% and 5.8–7% at 10, 10–20 and > 20 years respectively, and in Japan:156 0.5%, 4.1%, and 6.1% at 10, 20 and 30 years, respectively. In 3922 patients from five hospitals in China,157 the overall prevalence of CRC in patients with UC was low at 0.87% but the cumulative risk of developing CRC was 1.15% at 10 years, 3.56% at 20 years, and 14.36% at 30 years, which is comparable to Western cohorts.