Epidemiology and Natural History in Japan

Multicenter national surveys of PBC have been carried out 15 times since 1980 in Japan by the members of the Intractable Hepato-Biliary Disease Study Group in Japan supported by the Health Labour Sciences Research Grant. The subjects were 8,509 patients with PBC diagnosed and followed up between January 1, 1968 and December 31, 2011 at 520 hospitals and institutions throughout the country. We investigated the epidemiological trends and long-term prognosis of PBC in Japan based on national surveys. The annual incidence expressed as number of PBC patients has almost leveled off after 1989, and almost 70 % of patients with PBC were diagnosed in the asymptomatic stage. The prevalence of PBC gradually increased throughout the observation period. There were no major differences in clinical findings of PBC in Japan from those in the previous reports. Recently, the annual number of deaths caused by liver disease has decreased. The 5-year survival rates were 97.9 and 80.3 %, the 10-year survival rate 93.7 and 66.7 %, and the 20-year survival rate 84.2 and 52.1 %, respectively, showing significant differences among the groups (p < 0.0001). As results of examining changes in survival rate of PBC patients at each clinical stage, there was significant difference between the 1980s, 1990s, and 2000s for a-PBC and s-PBC. The results of the national surveys support the view that increased a-PBC with excellent prognosis and improvement in prognosis of all clinical stages of PBC may be important for increased prevalence in Japan.