Diagnostic Value of TB-IGRA, PPD, TB-DNA-PCR and TB-Ab in Silicosis Complicated with Tuberculosis

Purpose: The purpose of this article is to investigate the clinical value of TB-IGRA (Tuberculosis-Interferon Gamma Release Assay), PPD (Intradermal Terbuculin Test), TB-DNA-PCR (Tuberculosis-Deoxyribonucleic-Polymerase Chain Reaction) and TB-Ab (Tuberculosis-Antibody) in diagnosing silicosis complicated with pulmonary tuberculosis. Methods: 53 cases of suspected silicosis complicated with pulmonary tuberculosis were selected in the time span ranging from February 2017 to May 2019. TB-IGRA test, PPD test, TB-DNA-PCR and TB-Ab detection were performed. The sensitivity, specificity, positive predictive value and negative predictive value were calculated. Results: Silicosis and pulmonary tuberculosis were diagnosed in 11 cases, with an incidence of 20.75%. The positive rates of TB-IGRA, PPD, TB-DNA-PCR and TB-Ab were 66.04%, 30.19%, 5.67% and 26.42%, respectively. The sensitivity was 90.91%, 81.82%, 27.27% and 54.55% respectively. The specificity was 42.86%, 80.95%, 100% and 80.95% respectively. The positive predictive values were 28.57%, 50%, 100% and 42.86% respectively. The negative predictive values were 94.44%, 91.89%, 84% and 87.18%. The positive rate, sensitivity and negative predictive value of TB-IGRA were the highest, while the specificity of TB-DNA-PCR was the highest yet with low positive rate, sensitivity and positive predictive value. Conclusion: The positive rate and sensitivity of TB-IGRA were high, yet with poor specificity, so it was impossible to judge whether the cases belonged to active pulmonary tuberculosis. The combination of PPD and TB-DNA-PCR could improve the sensitivity, specificity and positive predictive value, and the diagnostic accuracy of active pulmonary tuberculosis, which showed satisfactory clinical value.