Value of subtypes of antimitochondrial antibodies in primary biliary cholangitis / 中华风湿病学杂志

ABSTRACT

Objective:To investigate the distribution and clinical significance of subtypes of antimitochondrial antibodies (AMA)-M2, M4, M9 in primary biliary cholangitis (PBC).Methods:A total of 1 367 patients were detected with AMA-M2, M4, M9 in Peking Union Medical College Hospital (PUMCH) from Jan 2014 to Dec 2019 and the clinical parameters were collected. The distribution patterns of AMA subtypes in different groups were analyzed and the diagnostic sensitivity and specificity of AMA subtypes in PBC were calculated. Chi-square test was used for statistical analysis.Results:In 1 367 patients, 236 of whom were positive for AMA subtypes. The positivity of AMA subtypes in female was significantly higher than in male (20.34% vs 9.41%, χ2=23.792, P<0.01). In addition, the positivity of AMA subtypes was significantly higher in 30-65 years old patients than in patients younger than 30 years old or older than 65 years old [(20.00%(193/965) vs 10.97%(17/155) vs 10.53%(26/247), χ2=17.209, P<0.01]. 110 patients with positive AMA subtypes were diagnosed with PBC. The diagnostic sensitivity and specificity of AMA-M2 were both desirable [94.64%(106/112) and 92.35%(1 159/1 255)]. Although the specificity of AMA-M4 was as high as 99.12%(1 244/1 255), its sensitivity was very low [15.18%(17/122)]. Combined detection of different AMA subtypes could not improve the diagnostic sensitivity and specificity significantly. Diseases other than PBC can be positive for AMA subtypes, predominantly for AMA-M2. Conclusion:Female and 30-65 years old patients were more frequently positive for AMA subtypes. AMA-M2 was the most valuable AMA subtype for diagnosing PBC.