Abstract:

Objective To evaluate the serodiagnostic value with tuberculosis (TB) antibody test in diagnosis of active pulmonary tuberculosis (PTB).Methods The clinical data and the results of serum Mycobacterium tuberculosis (MTB) antibody test based on IgG, IgM, LAM, 16kD, 38kD were collected from 495 patients with active PTB (experimental group) and 158 patients with non-tuberculosis respiratory diseases (control group), who hospitalized at Chongqing Public Health Medical Center during August 2016 to August 2017. Serodiagnosis was commenced in those patients after active PTB was confirmed by the comprehensive measures, including clinical manifestations, chest imaging, sputum bacteriological results or diagnostic anti-TB treatment responses. The sensitivity, specificity, positive predictive value and negative predictive value of the serum-tuberculosis antibody test in diagnosis of active PTB were evaluated.Results Out of 495 cases with active PTB, 340 cases showed positive sera TB antibody response (positive rate 68.7%); whereas, 55 out of 158cases with non-tuberculosis respiratory diseases revealed positive serum TB antibody detection test (positive rate 34.8%). The positive rate of serum TB antibody test in the experimental group was significantly higher than that in the control group (χ ²=57.50, P<0.01). The positive rate of serum TB antibody test (64.0%, 210/328) in the patients with bacteriologically negative pulmonary TB was lower than that (77.8%, 130/167) in the patients with bacteriologically positive PTB, and this difference was statistically significant (χ ²=9.83, P<0.01). In the experimental group, among 340 cases with positive TB antibody test results, 210 cases (61.8%, 210/340) were found to be positive with anti-LAM, 38kD and IgG antibodies at the same. The sensitivity, specificity, positive predictive value and negative predictive value of the serum TB antibody detection test based on IgG, IgM, LAM, 16kD, 38kD was 68.7% (340/495), 65.2% (103/158), 86.1% (340/395) and 39.9% (103/258) respectively; the Youden index and the overall consistent rate was 0.34 and 67.8% (443/653) respectively. Conclusion This study suggests that the serum TB antibody test has excellent accuracy and auxiliary diagnosis value in the diagnosis of patients with active PTB. The sensitivity of serum TB antibody test among the bacteriologically positive PTB patients is higher than that in the bacteriologically negative patients. The diagnostic sensitivity of PTB may be improved by the united detection of anti-LAM, 38kD and IgG antibodies.

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