Clinical characteristics and outcomes of primary sclerosing cholangitis and ulcerative colitis in Japanese patients

Background In Western countries, most patients with primary sclerosing cholangitis (PSC) have concurrent ulcerative colitis (UC). The number of patients with UC in East Asia has increased markedly over the past two decades. However, current clinical features of PSC and of PSC associated with UC (PSC-UC) have not yet been clarified in East Asia, particularly in Japan. We aimed to reveal the clinical courses and associations with UC in Japanese patients with PSC from the mutual viewpoint of PSC and UC. Methods We retrospectively retrieved medical records of patients with PSC (69) and UC (1242) who were diagnosed at Chiba University Hospital between June 1991 and August 2017. Results In the present cohort, 37 patients had PSC-UC; the cumulative risks of PSC in patients with UC and of UC in patients with PSC were 3.0% and 53.6%, respectively. We confirmed similar distinctive results by a Japanese nationwide survey, noting that younger patients with PSC had a notably high possibility of association with UC. From the viewpoint of the UC cohort, the occurrence of right-sided disease was significantly higher in patients with PSCUC than in those with UC (16.2% vs. 4.2%, P = 0.003). Pancolitis was more commonly observed in PSC-UC, and proctits/left-sided colitis was less commonly found in patients with UC. The number of patients with young-onset PSC-UC may be increasing similar to an increase in patients with UC in Japan. Conclusions In our cohort, the comorbidity rate of PSC-UC was higher than that obtained in previous reports. The incidence of PSC-UC and UC may increase in the future in East Asia, particularly in Japan.