QuantiFERON-TB gold plus in people living with HIV: independence from CD4+ T-cell counts in a low TB-burden setting

Background Tuberculosis screening is recommended for people living with HIV. The QuantiFERON-TB test measures the cell-mediated response against M. Tuberculosis . The Gold-In-Tube measures the response of CD4+ T-cells, often leading to indeterminate results. The new Gold-Plus (QFT-GP) also measures CD8+ T-cells response, thus reducing uncertainties. However, studies on people living with HIV, that would benefit from a test independent from CD4+ T-cells, are scarce. Objective This study addresses this gap by evaluating the performance of QFT-GP specifically in a large cohort of people living with HIV in a low TB-endemic setting. Methods We retrospectively evaluated the frequency of indeterminate QFT-GP tests in a cohort of people living with HIV with at least one test. We collected demographic data, CD4+ and CD8+ T-cell count at nadir and at the time of testing, and history of prior TB infection or treatment. We correlated the QFT-GP results to the CD4+ T-cell count. Results Six hundred and ninety five patients were included (males/females 72.5/27.5%), median age was 51 ± 14 years. Only 1,2% of tests were indeterminate, and there was no association with the CD4+ or CD8+ T-cell count at the moment of the test or at the nadir. Conclusions QFT-GP has few indeterminate results, even in patients with a low CD4+ T-cell count.