The auxiliary diagnostic performance of creation tuberculin skin test for mycobacterium tuberculosis compared with...

For bacteriologically negative suspected tuberculosis, immunological testing provides important diagnostic evidence. The traditional tuberculin skin test has poor specificity. QuantiFERON-TB Gold Plus (QFT-Plus, the latest generation of Interferon-Gamma Release Assays) and creation tuberculin skin test (C-TST) offer higher specificity and are less affected by non-tuberculous mycobacteria and BCG vaccine. However, the efficacy of QFT-Plus and C-TST in suspected tuberculosis remain unclear. We compared the performance of the QFT-Plus with the C-TST in auxiliary diagnosing tuberculosis in individuals with suspected tuberculosis.

The subjects were 137 patients suspected of tuberculosis, including 74 pulmonary tuberculosis (PTB) patients and 63 non-active pulmonary tuberculosis. All participants underwent both QFT-Plus and C-TST testing.

The sensitivities of QFT-Plus and C-TST in diagnosing PTB were 93.15 % and 86.49 %, respectively. The specificities of QFT-Plus and C-TST in diagnosing PTB were 40.35 % and 41.27 %, respectively. When QFT-Plus and C-TST were combined, the specificity increased to 58.73 %. The Area Under the Curves of Receiver Operating Characteristic in QFT-Plus and C-TST were 0.79 vs 0.67 (p < 0.05), respectively. In addition, the median IFN-γ level of TB2 tubes in the PTB group of QFT-Plus was significantly higher than that of TB1 tubes.

QFT-Plus and C-TST demonstrated diagnostic value in helping clinicians identify PTB and rule out non-patients to a certain extent, and the two methods had moderate agreement. The combined diagnosis statistically improved the specificity in auxiliary diagnosing PTB. Furthermore, the QFT-Plus appears more advantageous than C-TST for auxiliary diagnosing of tuberculosis.