Comparison of QuantiFERON-TB In Tube test and T-SPOT.TB with tuberculin skin test in HIV- infected individuals from an intermediate tuberculosis burden country

Abstract

Objective: The objective of this study was to evaluate the performance of T-SPOT.TB and QuantiFERON-TB In Tube test(QFT-IT) assays and tuberculin skin test(TST) for the diagnosis of latent tuberculosis infection in HIV infected individuals in South Korea. Design: A cross-sectional study was carried out at a tertiary hospital in South Korea to compare two forms of the interferon-γ release assays to TST. Results: We enrolled 95 patients with a median CD 4 cell count 429 cells/μl (range 18-1134) for the study. More positive assay results were obtained with T-SPOT.TB than for both TST and QFT-IT: 27.4 % compared to 11.6% and 15.8% ( P = 0.002 and P = 0.003) respectively. Positive results for TST were similar to those obtained with QFT-IT (P = 0.727). Agreement between the 3 tests was fair to good (QFT-IT vs TST, κ = 0.665 : T-SPOT.TB vs TST , κ = 0.456 : QFT-IT vs T-SPOT.TB, κ = 0.593) in all cases. Patients with positive results of QFT-IT, TST and T-SPOT.TB did not have statistically significant higher mean CD4 cell counts than those with negative results. Conclusion: When tested on HIV infected patients from South Korea, T-SPOT.TB, QFT-IT and TST showed fair to good agreement. T-SPOT.TB is more sensitive than both TST and QFT-IT. The result of all 3 tests was not affected by CD4 cell counts