A nationwide study of autoimmune liver diseases in the Faroe Islands: Incidence, prevalence, and causes of death 2004 - 2021.

Background and aims: Autoimmune liver diseases are rare diseases, and population-based studies on the epidemiology of autoimmune hepatitis (AIH), primary biliary cholangitis (PBC), and primary sclerosing cholangitis (PSC) are sparse. We aimed to assess the incidence of AIH, PBC, and PSC in the Faroe Islands. Methods: All cases of AIH, PBC, and PSC diagnosed in the Faroe Islands between January 1st , 2004, and December 31st , 2021, were included in this nationwide registry-based cohort study. In addition, we searched all medical records to assess diagnostic criteria and cause of death. Results: The incidences of AIH, PBC, and PSC in the Faroe Islands were 5.2, 2.5 and 0.7 per 100,000 population per year, respectively. Point prevalence per 100,000 population on December 31st 2021, was 71.8 for AIH, 38.5 for PBC, and 11.0 for PSC. Nine AIH patients died after a median of 3 years, three died of hepatocellular carcinoma (HCC), and two died of liver failure. Five PBC patients died after a median of 7 years, one of HCC and one of liver failure. One PSC patient died of cholangiocarcinoma. Conclusion: The incidence and prevalence of AIH, PBC and PSC in the Faroe Islands are among the highest reported in population-based settings.