Evolutionary relationship between antimitochondrial antibody positivity and primary biliary cholangitis in Taiwan: a 16-year hospital cohort study

BACKGROUND: How antimitochondrial antibody (AMA)-positive patients evolve to have primary biliary cholangitis (PBC) in viral hepatitis-endemic areas is unknown.

OBJECTIVES: We aimed to investigate this evolution in Taiwan.

DESIGN/METHODS: A 16-year medical center-based cohort study of 2,095,628 subjects was conducted in Taiwan, an Asian country endemic to viral hepatitis. AMA-positive subjects were those with positive AMA with alkaline phosphatase (ALP) ⩽1.5 times the upper limit of normal (ULN), and PBC was defined as positive AMA with ALP >1.5 × ULN.

RESULTS: AMA-positive subjects had a lower average age- and sex-adjusted prevalence than PBC patients (4.68/10 5 versus 11.61/10 5, p  = 0.0002), but their incidence was comparable (0.99/10 5 versus 1.12/10 5, p  = 0.36). The former group had a borderline significantly lower mean age (56.59 years versus 58.10 years, p  = 0.06) and a lower female-to-male ratio (2.85:1 versus 5.44:1, p  < 0.0001). Both AMA-positive subjects (prevalence change: 20.0%, p  < 0.01; incidence change: -9.2%, p  < 0.01) and PBC patients (prevalence change: 14.6%, p  < 0.01; incidence change: -4.7%, p   <  0.01) prevalence rate increased but the incidence rate decreased. Among the 423 AMA-positive subjects, 77 (18.2%) developed PBC, for a mean duration of 1.757 years. Compared with AMA-positive subjects, PBC patients had similar concurrent chronic hepatitis B (CHB) rates (2.7% versus 4.3%, p  = 0.197) but lower chronic hepatitis C (CHC) rates (3.69% versus 15.60%, p  < 0.01).

CONCLUSION: PBC was more prevalent than AMA-positive subjects, and PBC patients had a higher female-to-male ratio than AMA-positive subjects, of whom 18.2% developed PBC (mean lag: 1.757 years). Upward trends in prevalence rates and downward trends in incidence rates were noted for both AMA-positive subjects and PBC. CHB was rare, CHC was more prevalent among PBC patients than the general population, and CHC was less prevalent among PBC than among AMA-positive subjects.