Overlap of autoimmune hepatitis and primary biliary cirrhosis: an evaluation of a modified scoring system.

Objective: The coexistence of autoimmune hepatitis (AIH) with primary biliary cirrhosis (PBC) as an overlap syndrome has been previously described. The ability to detect AIH overlap with a revised version of the International Autoimmune Hepatitis Group (IAHG) scoring system, however, remains unknown. Our specific aim was to evaluate the revised IAHG scoring system and its ability to identify AIH overlap in PBC.

Methods: One hundred forty-one PBC patients with first-time visits to the Mayo Clinic from January 1, 1990 to December 31, 1992 were evaluated. The calculation of individual revised IAHG scores was performed and compared to original IAHG scores.

Results: Among 137 PBC patients with available liver histologies, use of the original IAHG scoring system detected "definite" and "probable" AIH overlap among 2.2% and 62% of cases, respectively. Application of the revised IAHG scoring system, however, revealed no individuals (0%) with definite AIH overlap (>15 points). Twenty-six subjects (19%) fulfilled IAHG criteria for probable AIH overlap (10-15 points). The presence of antinuclear antibody and/or smooth muscle antibody positivity (p = 0.05), other autoimmune disorders (p < 0.01), and total histological score (p < 0.001) were significantly greater in the PBC plus probable AIH group than in subjects with PBC alone.

Conclusion: A reduction in the prevalence of definite 2.2% vs 0%) and probable (62% vs. 19%) AIH overlap among PBC subjects was observed with use of the revised IAHG coring system relative to the original criteria. Applicability of the revised IAHG scoring system, however, remains questionable, as nearly 20% of PBC patients will be classified with probable AIH overlap.