Diagnosis of tuberculosis infection by tuberculin skin test and a whole-blood interferon-γ release assay in patients considered for anti–tumor necrosis factor-α therapy

To assess the performance of QuantiFERON®-TB Gold in-Tube (QFT-GIT; Cellestis, Carnegie, Australia) and tuberculin skin test (TST) in patients with immune-mediated inflammatory diseases (IMID), before anti–tumor necrosis factor-α (TNF-α) therapy, and to compare the results with those from the healthy population. Three hundred fourteen subjects (214 with IMID and 100 controls) underwent simultaneous QFT-GIT and TST. QFT-GIT was positive in 21% of IMID patients and in 16% of controls (P = 0.29). Among IMID patients, 21% tested positive by QFT-GIT and 24%, by TST (P = 0.30). Positive QFT-GIT results were not affected by immunosuppressive therapy (odds ratio, 0.78; 95% confidence interval [CI], 0.36–1.68; P = 0.52). Agreement between both tests in those patients who tested positive by one of the tests was 50% (95% CI, 37.2–62.8). QFT-GIT is useful for identifying IMID patients requiring treatment of latent tuberculosis before anti-TNF therapy. However, given the poor agreement between TST and QFT-GIT, we advocate a strategy of simultaneous testing to optimize diagnostic sensitivity.