Abstract
Objective: We compared the usefulness of tuberculin skin test (TST) and three interferon-gamma release assays (IGRAs) (QuantiFERON-TB Gold (QFT-2G), QuantiFERON-TB Gold In-tube (QFT-3G), T-SPOT.TB) as the supportive method of diagnosing pulmonary tuberculosis (TB).
Methods: The subjects were 70 patients who required the differentiation of pulmonary TB clinically. The final clinical diagnosis of pulmonary TB in 22 patients and non-pulmonary TB disease in 48 patients was established by clinical specimens.
Results: In 22 patients with pulmonary TB, the positive response rate was 60% on TST, 80% on QFT-2G, 85% on QFT-3G and 95% on T-SPOT.TB. In 48 patients with non-pulmonary TB disease, the positive response rate was 47% on TST, 9% on QFT-2G, 9% on QFT-3G, 13% on T-SPOT.TB. Indeterminate results on three IGRAs were recognized in one patient each on QFT-2G and QFT-3G among patients with pulmonary TB in three patients on QFT-2G and two patients on QFT-3G among patients with non-pulmonary TB disease. However, there were no indeterminate results on T-SPOT.TB in either patient group. Patients with false-negative or indeterminate results on IGRAs had severe underlying diseases or were receiving immunosuppressive treatments.
Conclusions: T-SPOT.TB provided the best positive response rate for patients with pulmonary TB among three IGRAs, although T-SPOT.TB may have problems in the specificity of diagnosing TB disease. Therefore, we think it is important to perform T-SPOT.TB in combination with QFT to elevate the sensitivity of the diagnosis of TB disease based on the findings in this study.
- © 2011 ERS