Baseline Hepatic Steatosis Influences Longitudinal FIB-4 Trajectories During TNF Inhibitor Therapy in Axial Spondyloarthritis

Abstract Objectives: Whether baseline hepatic steatosis influences longitudinal Fibrosis-4 (FIB-4) trajectories during TNF inhibitor therapy in axial spondyloarthritis (axSpA) remains unknown. This study addressed this question. Methods: This retrospective longitudinal cohort study included 154 patients with axSpA treated with TNF inhibitors for at least 6 months. Patients were classified according to baseline ultrasonographic hepatic steatosis, and FIB-4 scores were compared between baseline and the final follow-up visit. Results: Baseline FIB-4 values were higher in patients with hepatic steatosis (p=0.035). During follow-up, patients without steatosis showed a significant increase in FIB-4, whereas those with steatosis demonstrated a non-significant decrease. Delta FIB-4 differed significantly between groups (p=0.008), while FIB-4 values remained within the low-risk range throughout follow-up. Findings were similar across sex, TNF inhibitor type, and steatosis grade. Longer cumulative biologic exposure was associated with smaller changes in FIB-4. Conclusion: Baseline hepatic steatosis was associated with distinct longitudinal FIB-4 trajectories during TNF inhibitor therapy. Rather than indicating progressive liver fibrosis, these findings suggest that baseline hepatic status substantially influences the interpretation of serial FIB-4 measurements in patients with axSpA. If confirmed prospectively, baseline hepatic steatosis should be considered when using FIB-4 for longitudinal liver monitoring during biologic therapy.