Title Diagnostic difficulties of autoimmune hepatitis in adults: a systematic review of diagnostic scoring systems and the repositioning proposed by the 2025 EASL/BSG guidelines

Autoimmune hepatitis (AIH) is a chronic liver disease with a notoriously challenging diagnosis, given the absence of a pathognomonic marker and overlap with other cholestatic, metabolic, and drug-induced liver diseases. This systematic review aims to synthesize the main diagnostic difficulties reported in the literature regarding AIH in adults and to analyze how the 2025 EASL and BSG clinical practice guidelines reposition diagnostic criteria in comparison to previous scoring systems (1993 Classical criteria, 1999 Revised/ERDHAI score, 2008 Simplified criteria). A narrative synthesis approach will be adopted given the expected heterogeneity across primary validation studies and the risk of incorporation bias inherent to the diagnostic scores under evaluation.