Non‐alcoholic fatty liver disease in patients with autoimmune hepatitis

Background and Aim The incidence of non‐alcoholic fatty liver disease (NAFLD) is increasing all over the world. NAFLD develops in patients with liver disease, including patients with autoimmune hepatitis (AIH). NAFLD and AIH have some similar laboratory and histological findings. The aim of this study was to elucidate the characteristics of AIH patients with NAFLD. Methods We re‐evaluated the nationwide survey performed in Japan in 2015 of AIH patients diagnosed between 2009 and 2013. Results A total of 1151 subjects (144 men and 1007 women) were enrolled in the present study. The overall prevalence of NAFLD was 17.0%. Compared to AIH without NAFLD, AIH patients with NAFLD had the following characteristics: (i) low female‐to‐male ratio, (ii) older age, (iii) mild elevation in hepatobiliary enzymes, (iv) histologically progressive fibrosis and mild plasma cell infiltration or mild lobular hepatitis, (v) lower prevalence of prednisolone administration and higher prevalence of ursodeoxycholic acid administration, (vi) higher levels of hepatic enzymes and immunoglobulin G after treatment, and (vii) similar prevalence of autoimmune and malignant complications. Conclusion AIH patients with NAFLD have many features that are different from AIH patients without NAFLD. Understanding these differences is essential for the proper diagnosis and treatment of AIH patients with NAFLD. Autoimmune hepatitis (AIH) patients with non‐alcoholic fatty liver disease (NAFLD) have many features that are different from AIH patients without NAFLD. Understanding these differences is essential for proper diagnosis and treatment of AIH patients with NAFLD.