Diagnostic accuracy of interferon-gamma release assays for diagnosis of smear-negative pulmonary tuberculosis: a systematic review and meta-analysis

Introduction The diagnosis of smear-negative pulmonary tuberculosis (SNPTB) is challenging. Interferon gamma-release assays (IGRAs) may be helpful in early diagnosis among these patients resulting in prompt treatment and favorable outcomes. Methods We performed a comprehensive search from each databases' inception to April 5, 2021. The studies that provided sufficient data regarding the sensitivity and specificity of IGRAs included QuantiFERON-TB Gold In-Tube (QFT-GIT), T-SPOT.TB, or QuantiFERON-TB Gold Plus for diagnosis of SNPTB were included. Results Of 1,312 studies screened, 16 studies were included; 11 QFT-GIT, 2 T-SPOT.TB, and 3 QFT-GIT and T-SPOT.TB. For diagnosis of SNPTB, QFT-GIT had sensitivity of 0.77 (95% CI 0.71-0.82), specificity of 0.70 (95% CI 0.58-0.80), diagnostic odds ratio (DOR) of 8.03 (95% CI 4.51-14.31), positive likelihood ratio (LR) of 2.61 (95% CI 1.80-3.80), negative LR of 0.33 (95% CI 0.25-0.42), and area under receiver operating characteristic (AUROC) of 0.81 (95% CI 0.77-0.84). T-SPOT.TB had sensitivity of 0.74 (95% CI 0.71-0.78), specificity of 0.71 (95% CI 0.49-0.86), DOR of 6.96 (95% CI 2.31-20.98), positive LR of 2.53 (95% CI 1.26-5.07), negative LR of 0.36 (95% CI 0.24-0.55), and AUROC of 0.77 (95% CI 0.73-0.80). The specificity seemed lower in the subgroup analyses of studies from high tuberculosis burden counties compared to the studies from low tuberculosis burden. Conclusion IGRAs do have insufficient diagnostic performance for SNPTB. However, the tests are still helpful to exclude tuberculosis among patients with low pre-test probability. Registry: PROSPERO: CRD42021274653.