ORIGINAL ARTICLE Clinical Characteristics of Ulcerative Colitis Associated with Primary Sclerosing Cholangitis in Korea Byong Duk Ye, MD,* Suk-Kyun Yang, MD,* Sun-Jin Boo, MD,* Yun Kyung Cho, MS,* Dong-Hoon Yang, MD,* Soon Man Yoon, MD,* Kyung Jo Kim, MD,* Jeong-Sik Byeon, MD,* Seung-Jae Myung, MD,* Chang Sik Yu, MD, † Sung-Cheol Yun, PhD, ‡ and Jin-Ho Kim, MD* Background: Primary sclerosing cholangitis (PSC) is well known as one of the extraintestinal manifestations of ulcerative colitis (UC). However, the prevalence of PSC in UC patients to- gether with the clinical characteristics and outcomes of UC asso- ciated with PSC (UC-PSC) are not clear in Asians. Methods: We retrospectively reviewed the medical records of UC patients who were registered and followed up at the Asan Medical Center. The prevalence of PSC in UC and the clinical features of UC-PSC compared with matched UC without PSC were investigated. Results: A total of 1849 patients diagnosed with UC between July 1977 and September 2009 were reviewed. Among these, 21 UC-PSC patients (1.1%) were identified. The cumulative probability of PSC after diagnosis of UC was 0.71% after 1–5 years, 1.42% af- ter 10 years, 2.59% after 15 years, and 3.35% after 20–25 years. Compared with 63 matched UC alone patients, UC-PSC showed pancolitis (95.2%), rectal sparing (38.1%), and backwash ileitis (42.9%) more frequently (P < 0.001). During follow-up, three of 21 UC-PSC patients (14.3%) were diagnosed with colorectal neo- plasia and three patients (14.3%) died of PSC-associated complica- tions. UC-PSC patients were associated with increased probability of colorectal neoplasia development (P ¼ 0.036) and a trend toward increased mortality compared with the UC alone group. Conclusions: The prevalence of PSC in Korean UC patients appears to be lower than that of Western patients. Similar to Cau- casians, UC-PSC shows unique colonoscopic features and is asso- ciated with more frequent colorectal neoplasia development and poor prognosis in Korea. (Inflamm Bowel Dis 2011;17:1901–1906) Key Words: ulcerative colitis, primary sclerosing cholangitis, Korea C hronic ulcerative colitis (UC) is known to be associ- ated with various extraintestinal manifestations that can involve almost every system. 1 Extraintestinal organ systems involved in UC include the hepatobiliary system, musculoskeletal system, mucocutaneous system, genitouri- nary system, and the eyes. 2 Primary sclerosing cholangitis (PSC) is a chronic inflam- matory disease of the biliary tree resulting in biliary cirrhosis and hepatic fibrosis. 3–6 PSC is the most specific hepatobiliary involvement of UC, with the prevalence varying from 2.1% to 7.6% in Western studies. 7–13 On the contrary, the prevalence of UC in patients with PSC was reported to be 44% to 71% in Western studies. 14–17 With regard to the clinical characteris- tics of UC associated with PSC (UC-PSC), Western studies have reported that it is associated with increased frequency of pancolitis, backwash ileitis, and rectal sparing. 1,18,19 UC-PSC patients also showed milder colonic disease activity than patients with UC alone. 19–21 Furthermore, most studies in Western countries have identified PSC in UC as a significant risk factor for colorectal neoplasia (CRN) when com- pared with patients with UC alone, 22–28 although some have not. 29–31 UC-PSC has also been reported to be associated with increased mortality compared with UC alone. 18 However, there are few studies on the epidemiology, clinical characteristics, and prognosis of patients with UC- PSC in Asian populations. 32–35 In Japan, one small-scale single-center study reported that the prevalence of PSC in Japanese UC patients was 2.5%, 32 but a more recent larger- scale hospital-based study demonstrated that it was just 0.8%. 33 In a Korean hospital-based study, the prevalence of PSC in Korean UC patients was 1.0%. 34 However, the clini- cal characteristics and course of UC-PSC in East Asians have not been properly investigated yet, as these studies included only three or four patients with UC-PSC. 32–34 In this study we tried to identify the prevalence of PSC in patients with UC and the clinical features of UC-PSC patients compared with a control group of matched UC patients without PSC at a single tertiary center in Korea. Received for publication September 8, 2010; Accepted October 11, 2010. From the *Department of Gastroenterology, † Department of Colon and Rectal Surgery, ‡ Division of Biostatistics, Center for Medical Research and Information, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea. Reprints: Suk-Kyun Yang, MD, Department of Gastroenterology, University of Ulsan College of Medicine, Asan Medical Center, 388-1 Pungnap-dong, Songpa-gu, Seoul, 138-736, Korea (e-mail: sky@amc. seoul.kr) Copyright V C 2010 Crohn’s & Colitis Foundation of America, Inc. DOI 10.1002/ibd.21569 Published online 16 December 2010 in Wiley Online Library (wileyonlinelibrary.com). Inflamm Bowel Dis  Volume 17, Number 9, September 2011 1901