Autoimmune hepatitis in a demographically isolated area of Australia

Background: Previous studies describing autoimmune hepatitis (AIH) come from liver transplant centres in which a skewed distribution of cases may give a misleading picture of the incidence of AIH and its natural history. This series describes AIH in a stable and demographically discrete population of patients in the Australian Capital Territory (ACT) and the surrounding region. Methods: In 42 patients with type 1 AIH (point prevalence 8 per 100 000 population), clinical, laboratory and histological features at presentation, response to initial therapy, details of maintenance therapy and outcome were recorded. Results: Consistent with other publications, the male-to-female ratio was 1:3, mean age at presentation was 53 years and 24% had cirrhosis at diagnosis. Most patients (86%) responded to initial therapy and 67% went into long-term remission. One patient died from liver failure and none required liver transplantation. Azathioprine was included in the treatment regimen in 74% of cases with doses generally <2 mg/kg. Azathioprine dose greater than or equal to 2 mg/kg was associated with better clinical outcome, but this did not reach statistical significance. A higher proportion of female patients had cirrhosis at presentation (9/10 vs 1/10; P = 0.24). Conclusion: In this Australian community-based study, type 1 AIH was primarily a disease of later life, responded to conventional immunosuppressive therapy and generally has a good prognosis. Further study of the use of azathioprine is warranted to determine the optimal dose.