Characterization of overlap syndrome between primary biliary cirrhosis and autoimmune hepatitis according to antimitochondrial antibodies status.

AIMS: Codification of variant forms between Primary Biliary Cirrhosis (PBC) and Autoimmune Hepatitis (AIH) has not been definitively standardized. The aim of this study was to compare among 102 consecutive patients, 2 subsets of overlap syndrome (OS, N=21) with and without antimitochondrial antibody (AMA) to two groups of patients with typical PBC (N=43) or AIH (N=38).

METHODS: OS was defined by the presence in the same patient of at least 2 of 3 accepted criteria of PBC and AIH. Twelve patients with OS were AMA negative and 9 were AMA positive.

RESULTS: A lower level of alanine transaminase (139+/-48 vs 269+/-154 IU/L, P<0.05) and a trend towards a higher level of alkaline phosphatase or gamma-glutamyl transpeptidase was observed in OS without AMA than in OS with AMA (693+/-200 vs 544+/-124 IU/L; 370+/-66 vs 241+/-77 IU/L, respectively). All AMA-negative patients with OS had antinuclear and/or anti-smooth muscle antibodies. OS without AMA differed from those with AMA in that they had more severe bile duct damage including destructive cholangitis (P<0.05), ductopenia (P<0.05), ductular hyperplasia (P<0.05) and a higher METAVIR fibrosis score (2.5+/-0.3 vs 1.3+/-0.3, P<0.05). The response to therapy was not different between PBC, AIH and OS.

CONCLUSIONS: According to the presence of AMA, 2 homogeneous subgroups of patients with overlap syndrome between PBC and AIH may be identified. AMA status affects clinical presentation and liver disease severity of OS.