Poor performance of anti-mitochondrial antibodies for the diagnosis of primary biliary cholangitis in female Colombian patients: A single-center study

Abstract

BACKGROUND

Primary biliary cholangitis (PBC) is a serious disease that causes significant morbidity. PBC is confirmed with liver biopsy but autoantibodies are frequently used as proxies for diagnosis. The performance of autoantibodies for the diagnosis of PBC seems to vary widely across populations.

AIM

To assess the diagnostic performance of several autoantibodies for the diagnosis of PBC in Latin American individuals.

METHODS

We studied 85 female adult Colombians, 43 cases with biopsy-confirmed PBC and 42 controls in whom a liver biopsy ruled out PBC. Plasma anti-mitochondrial antibodies (AMAs), anti-smooth muscle antibodies (ASMAs) and anti-nuclear antibodies (ANAs), as well as total immunoglobulin (Ig) M and IgG were determined using immunofluorescence or enzyme-linked immunosorbent assay in all study participants within 1 year of the biopsy. For all variables, values analyzed were those closest to the date of the biopsy. Patients with viral or alcoholic hepatitis were excluded.

RESULTS

Mean age at diagnosis was 58.7 years for cases and 56.9 years for controls, and the body mass index was lower among cases. Most cases received ursodeoxycholic acid, while most controls received vitamin E. Sjögren syndrome and Hashimoto’s thyroiditis were the most frequent autoimmune comorbidities of PBC. The prevalence of AMA positivity among PBC cases was unexpectedly low. The sensitivity and specificity values were respectively 44.2% and 76.2% for AMA, 74.4% and 38.1% for ANA, 14.0% and 73.8% for ASMA, 26.7% and 80.0% for IgG, and 57.1% and 85.7% for IgM. The combination of positive AMA plus positive IgM had 91% positive predictive value for PBC. Among AMA-negative cases, the most prevalent antibodies were ANA (87.5%). In all, 62% of AMA-positive and 84.6% of IgM-positive individuals had fibrosis in their biopsy.

CONCLUSION

AMA positivity was very low among female Latin American patients with PBC. The performance of all antibodies was quite limited. These results highlight the urgent need for better PBC biomarkers.

Keywords: Primary biliary cholangitis, Antibodies, Anti-mitochondrial antibodies, Latin America, Anti-smooth muscle antibodies

Core Tip: Primary biliary cholangitis (PBC) is confirmed by liver biopsy, but autoantibodies are frequently employed as an indirect diagnostic method. We studied 85 female adult Latin American patients, 43 with biopsy-confirmed PBC and 42 in whom liver biopsy ruled out PBC. The prevalence of anti-mitochondrial antibodies among PBC cases was only 44.2%. Anti-nuclear antibodies and anti-smooth muscle antibodies had similarly low diagnostic performance. Eighty-two percent of immunoglobulin M-positive individuals had fibrosis in their biopsy. Among female Latin American patients with PBC, the performance of any individual antibody for PBC diagnosis was quite limited.