Epidemiology and the initial presentation of autoimmune hepatitis in Sweden: A nationwide study

OBJECTIVE: Autoimmune hepatitis (AIH) is a chronic liver disease, which if untreated can lead to cirrhosis and hepatic failure. The aim of the study was to investigate the incidence, prevalence, diagnostic tradition and clinical initial presentation of AIH. MATERIAL AND METHODS: Analyses were performed in 473 patients identified as having probable or definite AIH. RESULTS: The incidence of AIH was 0.85/100,000 (95% CI 0.69-1.01) inhabitants, which is somewhat lower than reported previously. The point prevalence amounted to 10.7/100,000 (95% CI 8.8-13.1), and 76% of the cases were females. The age-related incidence curve was bimodal but men were found to have only one incidence peak in the late teens, whereas women had a peak after menopause. AIH was presented as a spectrum of clinical settings from detected "en passant" to acute liver failure. Almost 30% of patients already had liver cirrhosis at diagnosis. Autoantibodies indicative of AIH type 1 were found in 79% of cases. Other concomitant autoimmune diseases were frequently found (49%). CONCLUSIONS: The incidence and prevalence figures confirm that AIH is a fairly uncommon disease in the Swedish population. Symptoms at presentation were unspecific, but almost half of the patients were jaundiced, with around 30% having liver cirrhosis. The majority of Swedish AIH patients had AIH type 1.