Autoimmune hepatitis: Epidemiology, prognosis and follow-up

Aims: This thesis includes one study (Study I) focused on epidemiological data regarding autoimmune hepatitis (AIH) and three studies (Studies II-IV) on follow-up of AIH. Patients and methods: Patients with AIH code K73.2 or K75.4 with special reimbursement in the Social Insurance Institution of Finland registry were included. Data from the Finnish cancer register were used to calculate standardized mortality ratios (Study I). All patients with AIH diagnosis in Helsinki University Hospital were included in the retrospective study of the impact of liver histology on disease progression (Study II). Twelve patients with AIH were investigated with magnetic resonance spectroscopy, liver biopsy, and transient elastography (Study III). Follow-up biopsies of all Finnish liver transplant recipients with AIH as an indication for transplantation were combined with clinical data to evaluate the prognosis and risk factors for AIH recurrence and graft loss (Study IV). Results: We showed that the median AIH incidence between 1995 and 2015 was 1.0/100,000/year (1.2/100,000/year in women and 0.38/100,000/year in men) and increased from 0.28/100,000 to 1.0/100,000 during the study period. The prevalence of AIH in 2015 was 14/100,000, 23/100,000 in women and 6.6/100,000 in men). The standardised mortality ratio was increased in all age groups and both genders. The most prevalent excessive causes of mortality when compared to the standard population were hepatocellular carcinoma, liver cirrhosis, and AIH per se (Study I). We identified the following prognostic variables for advancing fibrosis or cirrhosis in follow-up biopsies: interface or total inflammation, necrosis, cholestasis, or rosette formation in the baseline biopsy. If inflammation in the follow-up biopsies was constantly grade two or more in the Metavir scale, the hazard ratio (HR) for cirrhosis was 5.1, (95 % Confidence interval (CI) 1.6-16.2), p