Epidemiology and surveillance of autoimmune hepatitis in Asia.

Autoimmune hepatitis (AIH) is a chronic inflammatory liver disease that mainly injures the hepatocytes. The autoimmune disease might be involved in its aetiology, but this remains to be confirmed. Recently epidemiological studies of AIH in Asia have been broadly conducted, revealing characteristics and management of AIH patients in Asia. In East Asia, most AIH patients are type 1, and type 2 AIH is very rare. However, type 2 AIH in South Asia is as frequent as in Europe and the USA. HLA-DR4 is associated with the characteristics of type 1 AIH in East Asia, whereas HLA-DR3 occurs in AIH patients from South Asia. AIH prevalence worldwide is increasing, and several studies have reported a prevalence of 19.44, 22.80 and 12.99 per 100 000 people in Europe, the USA and Asia respectively. A meta-analysis of studies on AIH showed similar annual incidence rates for all regions, with 1.31, 1.37 and 1.00 per 100 000 people in Asia, Europe and the USA respectively. The increase in the rates could be attributable to the increased awareness of disease concepts and diagnosis. In South Asia, most cases were diagnosed as AIH only after having progressed to cirrhosis, which may cause a higher mortality rate in South Asia than in East Asia. Therefore, the early diagnosis and treatment of AIH patients can improve the current situation in Asia.