Significance of autoantibody seropositivity in children with obesity and non‐alcoholic fatty liver disease

Summary Background Autoantibodies are frequently positive in adults with nonalcoholic fatty liver disease (NAFLD) without concurrent autoimmune hepatitis (AIH). The clinical significance of this is unknown in children. Objective To determine the prevalence of autoantibody positivity in pediatric NAFLD and to evaluate its association with disease severity. Methods Multicenter, retrospective study of patients ≤18 years of age with biopsy‐confirmed NAFLD. Descriptive statistics were used and groups were compared using Wilcoxon‐Mann Whitney or χ2 testing, and multivariable logistic regression was used for binary or ordinal outcomes. Results One hundred and thirty six patients with a median age of 14 years were included. The median body mass index Z‐score was 2.5 (interquartile range 2.2, 2.6). Positive antinuclear antibody (ANA), anti‐smooth muscle antibody (ASMA), anti‐liver‐kidney microsomal antibody, or any combination of autoantibodies were observed in 22%, 14%, 0%, and 33% of patients, respectively. The proportion of patients with a steatosis score ≥2 was significantly higher in those with positive ANA (P = .045). In the multivariable regression analysis, positive ANA was associated with increased odds of steatosis score ≥2 (odds ratio, 5.91; 95% confidential interval, 1.50‐23.26), after controlling for potential confounders. No other significant histology differences were seen between the groups. Conclusions Positive ANA and ASMA are common in children with NAFLD; however, anti‐LKM positivity is not. ANA positivity is associated with more severe steatosis.