Current epidemiology and clinical characteristics of autoimmune liver diseases in South Korea.

Autoimmune liver diseases including autoimmune hepatitis (AIH) and primary biliary cholangitis (PBC) are rare diseases. The aim of this review is to examine the epidemiology and clinical characteristics of AIH and PBC in South Korea. There were 4,085 patients registered as AIH in the Rare Intractable Disease Registry of Korea between 2009-2013, with a median age of 56 years and female-to male ratio of 6.4. The age-adjusted incidence and prevalence of AIH were 1.07/100,000/year and 4.82/100,000 persons, respectively. Among the patients, 1.1% underwent liver transplantation, and case fatality was 2.18%. Liver cirrhosis at diagnosis was accompanied in 23%; liver biopsy was performed in 75.2%, and prednisolone therapy or prednisolone and azathioprine combination therapy was done in 73% with a remission rate of 86%. There were 2,824 patients with PBC (≥20 years) registered in Korea between 2009-2013 with a median age of 57 years and female-to male ratio of 6.2. The age-adjusted incidence and prevalence of PBC were 0.86/100,000/year and 4.75/100,000 persons, respectively. Among the patients, 2.5% underwent liver transplantation, and case fatality was 2.2% with a 5-year transplantation-free survival of 95.4%. Ursodeoxycholic acid (UDCA) was prescribed in 90% of the patients with a UDCA inadequate response rate of 30%. In conclusion, AIH and PBC are rare but mostly treatable diseases if diagnosed in the early stages. However, scarce data, low awareness, delayed diagnosis and non-availability of 2nd line therapeutics are important issues to be solved. Therefore, governmental support for research and drug development and nationwide cooperative studies are warranted.