Clinical utility of QuantiFERON-TB GOLD In-Tube and tuberculin skin test in patients with tuberculous pleural effusions.

Interferon gamma release assays are used for diagnosing latent tuberculosis (TB); however, their role in diagnosing tuberculous pleural effusion (TPE) is not defined. The aim of this study was to evaluate the usefulness of the QuantiFERON-TB Gold In-Tube assay (QFT-IT) and compare this assay with the tuberculin skin test (TST) for diagnosing TPE in settings where tuberculosis is endemic and bacillus Calmette-Guérin vaccination is mandatory. The TST and QFT-IT test were conducted prospectively with 101 patients presenting with clinically suspected TPE. Of the 97 evaluable subjects, 54 had TPE. The sensitivity, specificity, positive predictive value, and negative predictive value were, respectively, 76.9%, 61.1%, 74.1%, and 64.7% for QFT-IT; 72.5%, 71.7%, 77.1%, and 66.7% for TST; and 83.7%, 45.7%, 68.3%, and 66.7% for QFT-IT plus TST. Thus, the QFT-IT test may be more useful than the TST for diagnosing TPE. Although the combination of QFT-IT and TST had higher sensitivity, it had poor specificity owing to the high prevalence of latent TB in our setting.