Pre-Diagnosis Alkaline Phosphatase and Antimitochondrial Antibody Positivity Vary by Race/Ethnicity Among Patients With Primary Biliary Cholangitis.

Abstract

Background: Diagnosis of primary biliary cholangitis (PBC) is made using alkaline phosphatase (ALP) and positive antimitochondrial antibody (AMA), but these biomarkers may vary by race. There is also little known about changes in ALP in the years prior to PBC diagnosis.

Methods: Using data from the Fibrotic Liver Disease Consortium, we used matched pairs to evaluate racial differences in ALP for up to 5 years prior to diagnosis. We also compared rates of AMA positivity by race.

Results: 1335 confirmed PBC patients were included: 769 (58%) non-Hispanic white (NHW); 110 (8%) Black; 138 (11%) Asian American Pacific Islander (AAPI); and 318 (24%) Hispanic. 774 patients had AMA test results. Black patients had significantly lower AMA positivity than NHWs. Black patients were less likely to be AMA-positive compared to NHW patients (OR = 0.50, 95% CI 0.29-0.86, p = 0.012). There were no significant differences in rates of AMA positivity between AAPI or  Hispanic versus NHW patients. All patient groups had elevated ALP for 2-5 years prior to diagnosis. ALP differed between Black and NHW patients only at specific times before diagnosis. There were no significant differences in ALP between Hispanic and NHW patients. AAPI patients had significantly lower ALP compared to NHWs.

Conclusion: In a diverse sample of PBC patients, we observed significant differences in AMA positivity and pre-diagnosis ALP levels by race. Future studies to better characterize PBC across racial/ethnic groups are warranted.