• Kiwon Cho, Eunha Cho, Soohoon Kwon, Sanghyuk Im, In Sohn, Sookhee Song, Hyeok Kim, and Suhyun Kim.
• Department of Internal Medicine, Seoul Medical Center, Seoul, Korea.
• Tuberc Respir Dis (Seoul). 2012 May 1; 72 (5): 416-25.

BackgroundThe sensitivities and specificities of interferon-gamma release assays (IGRAs) vary among different population studies, and the data on the routine use of IGRAs are limited. The aim of this study was to evaluate the role of QuantiFERON-TB Gold In-Tube (QFT-GIT) test in the diagnosis of active tuberculosis.MethodsWe conducted a prospective study, enrolling 77 patients with suspected pulmonary tuberculosis (TB), at a secondary care teaching hospital in Seoul.ResultsIn total, 12 (15.6%) patients showed indeterminate results due to positive control failure on the QFT-GIT test. Indeterminate results were significantly associated with the elderly, history of the intensive care unit stay, lymphocytopenia, especially low CD4 count, increased C-reactive protein and decreased protein levels. Of the 77 patients, 44 (57.1%) were diagnosed with active pulmonary tuberculosis, and the percentage of false negative results of the QFT-GIT was 36.4% (vs. 31.8% with TST). In the TB group with >65 years old (n=12), the proportions of the indeterminate (33.3% vs. 3.1%) and the false negative results (58.3% vs. 25.0%) of the QFT-GIT were significantly higher than in the younger TB group (n=32).ConclusionIndeterminate and false negative results of QFT-GIT test were not infrequent in tuberculosis, especially in the elderly. Care should be considered for the interpretation with the elderly, immunocompromised, chronic and severely diseased patients.

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