Comparison of QuantiFERON-TB Gold Plus, QuantiFERON-TB Gold In-Tube, and T-SPOT.TB among patients with tuberculosis.

OBJECTIVES: This study evaluated the efficacy of the following interferon (IFN)-γ release assays (IGRAs): QuantiFERON-TB Gold Plus (QFT-Plus), QFT-Gold In-Tube (QFT-GIT), and T-SPOT. TB (T-SPOT) with the quantitative values of IFN-γ response. METHODS: Blood samples were collected from patients with active tuberculosis (TB), latent TB infection (LTBI), individuals with previous TB infection, and healthy volunteers enrolled between May 2017 and June 2018. RESULTS: IGRAs results were analyzed in 175 subjects (76 had active TB, 14 had LTBI, 35 had prior TB infection, and 50 were healthy). QFT-Plus and QFT-GIT revealed equal efficacy for IFN-γ values, and the IFN-γ response in QFTs tended to increase with the spot counts in T-SPOT, with similar high sensitivities (approximately 90%) in the active TB group. The test concordance of two of three IGRAs was optimal among all subjects (κ coefficients: 0.82-0.96). Additionally, the median quantitative values of IFN-γ with QFT-Plus and QFT-GIT were higher in the active TB group than in the LTBI and previous TB groups. CONCLUSION: Three IGRAs showed equivalent efficacy with high sensitivities and higher IFN-γ response in active TB group than that in non-active TB group.