Autoimmune hepatitis in Denmark: Incidence, prevalence, prognosis, and causes of death. A nationwide registry-based cohort study

Background & Aims Population-based studies of the clinical course of autoimmune hepatitis are scarce. We conducted a nationwide study of incidence, prevalence, prognosis, and causes of death of autoimmune hepatitis in Denmark. Methods From nationwide healthcare registries we identified all Danish citizens diagnosed with autoimmune hepatitis in 1994–2012 and their liver biopsy data. We followed patients through January 2013 and examined age-standardized incidence and prevalence, mortality, prognostic factors, risk of hepatocellular carcinoma, and causes of death. We used Cox regression to compare patients’ mortality relative to a gender- and age-matched general population sample. Results We included 1721 autoimmune hepatitis patients. The incidence rate was 1.68 (95% confidence interval 1.60 to 1.76) per 100,000 population per year, and it doubled during the study period. Of the 1318 patients who were biopsied at diagnosis, 28.3% had cirrhosis. The 10-year cumulative risk of hepatocellular carcinoma was 0.7% (95% confidence interval 0.3 to 1.5). Male gender and cirrhosis were associated with high mortality and development of hepatocellular carcinoma. In the first year after diagnosis, patients with autoimmune hepatitis had six-fold higher mortality than the general population; later, their mortality remained two-fold higher. Their 10-year cumulative mortality was 26.4% (95% confidence interval 23.7 to 29.1). 38.6% of deaths were liver-related including 3.6% from hepatocellular carcinoma. Conclusions This nationwide population-based study of autoimmune hepatitis showed that the incidence increased during 1994–2012, and that the disease remains associated with a high mortality, particularly in the first year after diagnosis. Male gender and cirrhosis were adverse prognostic factors.