Methotrexate and biological therapy are not associated with fatty liver in rheumatoid arthritis—a cross-sectional study

The prevalence of non-alcoholic fatty liver disease (NAFLD) in patients with rheumatoid arthritis (RA) is approximately 30%. The relationship between conventional synthetic and biologic disease-modifying antirheumatic drugs (csMDARDs and bDMARDs) and NAFLD is complex and requires careful consideration in clinical practice. This study evaluates the impact of various treatment regimens and analyzes the relationship between NAFLD, defined by a controlled attenuation parameter (CAP) threshold of 275 dB/m, and liver fibrosis (liver stiffness measurement > 8 kPa) and clinical parameters in 170 RA patients. Treatment groups were categorized based on methotrexate (MTX) use (“YES” and “NO”) and the use of biologic agents, including tumor necrosis factor inhibitors (TNFi), interleukin-6 (IL-6) inhibitors, as well as non-treatment groups. The prevalence of NAFLD in RA patients was found to be 36%, primarily attributed to components of metabolic syndrome and obesity including body-mass index (BMI), waist (WC) and hip circumference (HC), alanine aminotransferase (ALT), aspartate aminotransferase (AST) (all p < .001) triglycerides (p = .049). No significant differences in NAFLD prevalence were observed between treatment groups or between MTX treatment groups (cumulative doses < 3 g and > 3 g; p = 1.0). Furthermore, TNFi treatment duration did not show a significant correlation with NAFLD (Spearman’s rho = 0.024, p = .897) or with fibrosis severity (Spearman’s rho = 0.087, p = .640). In contrast, the duration of IL-6 inhibitor treatment demonstrated a significant negative correlation with NAFLD (Pearson’s r=-0,41, p = .029). Methotrexate does not appear to influence NAFLD or fibrosis in RA patients. In contrast, long-term use of IL-6 receptor inhibitors may contribute to a reduction in NAFLD.