To evaluate the clinical value of tuberculosis interferon γ release assay (TB-IGRA) in the diagnosis of active pulmonary tuberculosis among the suspected pulmonary tuberculosis patients in the southwest region of China with high TB burden.

A total of 1627 suspected pulmonary tuberculosis patients from the Department of Infectious Diseases of Zhijin County People′s Hospital in Guizhou Province in China between December 20, 2018 and December 20, 2019 were enrolled for this study. Then TB-IGRA, tuberculin skin test (TST) and tuberculosis immunoglobulin (TB-Ig) were used respectively to diagnose the active pulmonary tuberculosis. And the sensitivity, specificity and accuracy were compared among the patients with TB-IGRA, TST, and TB-Ig, respectively. The influences of Bacillus Calmette-Guérin (BCG) vaccination on these tests were analyzed.

The sensitivity, specificity and accuracy of TB-IGRA were 91.26%, 80.13%, and 89.37%, respectively, and they were higher than those of TST or TB-IgG. The results of TB-IGRA diagnosis for active pulmonary tuberculosis among the suspected pulmonary tuberculosis patients were not affected by BCG vaccination (χ²=0.05, P=0.83). However, BCG vaccination affected the results of TST significantly (χ²=108.17, P<0.001).

TB-IGRA seems to be superior to TST or TB-IgG as a diagnostic tool for the detection of active pulmonary tuberculosis among the suspected pulmonary tuberculosis patients in southwest region of China with high TB burden and it is not affected by BCG vaccination.