Geoepidemiology of primary sclerosing cholangitis: a critical review.

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease of unknown origin, characterized by progressive destruction of bile ducts caused by diffuse inflammation and fibrosis. Previous epidemiological studies in Northern Europe and North America demonstrated that incidence and prevalence rates are ranging from 0.5 to 1.3 and from 3.85 to 16.2 per 100,000 inhabitants per year, respectively. It is of note that the incidence of PSC appears to be gradually increasing. We have extensively reviewed the geoepidemiology of PSC and attempted to place it in context with the incidence in Japan. In 2012, the clinical diagnostic criteria of IgG4-SC were established and published by the Japan Biliary Association, rendering it possible for physicians to clinically differentiate PSC from IgG4-SC. We conducted a new nationwide survey for PSC as well as IgG4-SC, and have identified 197 patients with PSC and 43 patients with IgG4-SC without pancreatic involvement. In this survey we estimated prevalence rate of PSC in Japan as 0.95, lower than those in North America and European countries. Also we identified other unique features of Japanese PSC patients, including 2 peaks in age distribution at diagnosis and fewer presences of comorbid inflammatory bowel diseases, occurring in only 34% of PSC. This data is placed in the perspective of the international experience on PSC.