Abstract:

Objective To explore the value of applying Mycobacterium tuberculosis IgG antibody test kit in the diagnosis of tuberculosis.Methods A total of 795 confirmed patients with tuberculosis diagnosed in Xi’an Chest Hospital from January 2013 to December 2016 were selected as the TB group; 185 patients with other lung diseases (except NTM) were selected as the control group, and 36 patients with non-tuberculosis mycobacteria (NTM) were selected as the NTM group. The sensitivity, specificity, positive predictive value and negative predictive value of TB antibody test kit in all patients were analyzed retrospectively in comparison with the clinical diagnosis and culture of the Mycobacterium tuberculosis as the gold standard. The positive rate of TB group versus NTM and control group was analyzed by chi-square test, and the application value of the method was evaluated.Results Using the clinical diagnosis standard as the standard, the sensitivity, specificity, positive predictive value, negative predictive value, missed diagnosis rate, misdiagnosis rate, prevalence rate, accuracy and Youden index were 42.01% (334/795), 82.81% (183/221), 89.78% (334/372), 28.42% (183/644), 57.99% (461/795), 17.19% (38/221), 78.25% (795/1016), 50.89% (517/1016), 0.25. Using tuberculosis culture results as the reference, the sensitivity, specificity, positive predictive value, negative predictive value, missed diagnosis rate, misdiagnosis rate, prevalence rate, accuracy and Youden index were 51.12% (160/313), 69.84% (491/703), 43.01% (160/372), 76.24% (491/644), 48.88% (153/313), 30.16% (212/703), 30.81% (313/1016), 64.07% (651/1016), 0.21. The positive rate of tuberculosis antibody test kit in the TB group, NTM group, and groups with smear positive pulmonary tuberculosis, smear negative pulmonary tuberculosis, tuberculous meningitis, tuberculous pleurisy/peritonitis, tuberculous pericarditis were 42.01% (33.4/795), 61.11% (22/36), 50.00% (80/160), 41.99% (97/231), 46.43% (13/28), 38.76% (138/356), 30.00% (6/20); no statistically significant difference was found between the positive rate of tuberculosis antibody testing between these different groups (χ ²=7.14, P=0.128). The positive rate of Mycobacterium tuberculosis IgG antibody test in TB group (42.01%,334/795), NTM group (61.11%,22/36) and control group (8.65%,16/185) was statistically different (χ ²=81.63, P=0.000) but the highest rate belonged to the NTM group, which might easily lead to misdiagnosis. Conclusion Because the sensitivity and accuracy of Mycobacterium tuberculosis IgG antibody test kit in detecting tuberculosis antibody are comparatively low, while the missed diagnosis and misdiagnosis rates are comparatively high, it is not recommended for clinical application anymore.

Key words: Tuberculosis, pulmonary, Antigen-antibody reactions, Microchip analytical procedures, Laboratory techniques and procedures, Evaluation studies