Long-term outcomes in antimitochondrial antibody negative primary biliary cirrhosis

OBJECTIVES: Antimitochondrial antibodies (AMA) are a sensitive and specific marker for primary biliary cirrhosis (PBC). AMAs are present in 95% of patients with PBC. However, 5% do not have AMAs and data on these patients is scarce. We aim to evaluate the long-term outcomes of patients with AMA negative PBC. METHODS: A retrospective chart review of 71 AMA negative PBC patients. Disease presentation, laboratory results, and clinical endpoints were recorded. AMA negative patients were matched on year of diagnosis to a control group of 71 AMA positive patients. RESULTS: Ninety-six percent of the AMA negative patients were of female gender with a median age at diagnosis of 55 years and a length of follow-up of 7.5 years vs. 86% females, a median age of 56 and a follow-up of 8.3 years in the control group. Mean total bilirubin and alkaline phosphatase levels were 0.7 mg/dL vs. 0.6 and 570 U/L vs 341, in AMA negative vs. AMA positive patients at presentation, respectively (p = NS). AMA negative patients did not differ in terms of age, serum IgM levels, ANA status, or length of follow-up. Notably, AMA negative patients had a significantly reduced survival free of liver-related complications including transplantation and death compared to AMA positive patients (p = 0.0182). CONCLUSION: In this large experience, AMA negative PBC patients had a significantly worse prognosis compared to AMA positive PBC patients. The reason for the difference in prognosis is unclear, as it may be true difference or reflect delays in case detection among AMA negative patients.