Prevalence of primary biliary cirrhosis-autoimmune hepatitis overlap syndrome

The prevalence of and the most appropriate way to diagnose the primary biliary cirrhosis (PBC)-chronic autoimmune hepatitis (AIH) overlap syndrome are uncertain. We investigated the prevalence of PBC and AIH and their level of overlap at a tertiary referral center, along with clinical, biochemical, and serologic characteristics.

We reviewed data from all patients with PBC (n = 609) and/or AIH (n = 15) examined at the Tufts Medical Center (Boston, MA) from January 1, 2000, to June 20, 2006. PBC was diagnosed based on 2 of the following 3 results: 6 months of positive results in tests for cholestatic liver enzymes, a positive result in a test for antimitochondrial antibodies, or a liver biopsy that indicated PBC. AIH was defined as an alanine aminotransferase level of 200 U/L or greater (≥ 5-fold above normal), a liver biopsy that indicated severe interface hepatitis, and levels of immunoglobulin G 2-fold or greater than that of normal.

Only 6 patients with PBC (1%) met the Paris criteria for the overlap syndrome. If we included 9 patients with PBC who did not meet the Paris criteria, but had results from liver enzyme tests and liver biopsy analyses that indicated improvement after treatment with prednisone, the prevalence was 15 (2.8%). This is at the low end of previously reported prevalence values for overlap of PBC and AIH (2%-20%).

The prevalence of the PBC-AIH overlap syndrome varies among medical centers. We propose that if the definition of PBC-AIH overlap syndrome be modified to include patients with unequivocal responses to prednisone despite not meeting the Paris criteria, this would improve treatment of patients.