Increase trend in the prevalence and male‐to‐female ratio of primary biliary cholangitis, autoimmune hepatitis, and primary sclerosing cholangitis in Japan

Aim Autoimmune liver diseases (AILD) including autoimmune hepatitis (AIH), primary biliary cholangitis (PBC), and primary sclerosing cholangitis (PSC) impose a significant burden on public health, and it is important to estimate their prevalence. We carried out a nationwide, hospital‐based, epidemiological survey of AIH, PBC, and PSC, and compared the results with those from previous surveys. Method We randomly selected health‐care facilities used in the survey from a list of all facilities in Japan. The selection rate was determined according to a stratification based on the facility characteristics and scale. We sent questionnaires to the selected facilities enquiring about the number and sex of patients with AILD who visited the facility in 2016. An identical survey was undertaken for AIH/PBC in 2004 and for PSC in 2007; we carried out a comparative analysis of these data. Results We selected 1793 departments from health centers all over Japan. Of them, 1078 (60.1%) responded to the questionnaires. The number of reported patients with AIH, PBC, and PSC was 8505, 10 847, and 906, respectively, and point prevalence was 23.9 (95% confidence interval, 23.3–24.5) for AIH (8.7 in 2004), 33.8 (33.0–34.6) for PBC (11.6 in 2004), and 1.80 (1.75–1.85) for PSC (0.95 in 2007) per 100 000 population. Male‐to‐female patient ratio of AILD was 1:4.3 for AIH (1:6.9 in 2004), 1:3.9 for PBC (1:7.1 in 2004), and 1:0.88 for PSC (1:1.4 in 2007). Conclusion The current study indicates an increasing trend of prevalence as well as male‐to‐female patient ratio of AILD in Japan.