Diagnostic performance of whole-blood interferon-γ assay and enzyme-linked immunospot assay for active tuberculosis

• Published in: Diagnostic microbiology and infectious disease Vol. 71; no. 2; pp. 139 - 143
• Main Authors: Lai, Chih-Cheng, Tan, Che-Kim, Lin, Sheng-Hsiang, Liao, Chun-Hsing, Huang, Yu-Tsung, Hsueh, Po-Ren
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.10.2011; Elsevier
• Subjects: Active tuberculosis; Adult; Aged; Australia; Biological and medical sciences; blood; Enzyme-Linked Immunospot Assay - methods; Female; Fundamental and applied biological sciences. Psychology; Humans; Infectious Disease; Infectious diseases; interferon-gamma; Interferon-gamma - blood; Interferon-gamma Release Tests - methods; Interferon-γ release assays; Internal Medicine; Male; Medical sciences; Microbiology; Middle Aged; Mycobacterium; Mycobacterium tuberculosis - pathogenicity; patients; Predictive Value of Tests; Prospective Studies; QFT-GIT; Rapid diagnosis; Reagent Kits, Diagnostic; T-SPOT.TB; Taiwan; tuberculosis; Tuberculosis - diagnosis; Tuberculosis - pathology; United Kingdom; Taiwan; Australia; United Kingdom; Rapid diagnosis; T-SPOT.TB; Interferon-γ release assays; QFT-GIT; Active tuberculosis; T-SPOT. TB; Infection; Whole blood; Enzyme; Cytokine; Diagnosis; Release; Gamma interferon
• ISSN: 0732-8893; 1879-0070; 1879-0070
• DOI: 10.1016/j.diagmicrobio.2011.05.013

The aim of this study was to compare the diagnostic performance of 2 interferon-γ release assays, an enzyme-linked immunospot assay (T-SPOT.TB; Oxford Immunotec Ltd., Oxford, UK) and the QuantiFERON-TB Gold in-Tube assay (QFT-GIT; Cellestis Ltd., Carnegie, Australia), in patients with suspected active tuberculosis (TB). From October 2009 to October 2011, a total of 200 patients with suspected TB were enrolled. Clinical and microbiological characteristics of the patients were collected and blood samples were obtained for T-SPOT.TB and QFT-GIT assays. Among the 200 subjects, 98 (49%) had culture-confirmed TB, 18 (9%) had probable TB, and the remaining 84 (42%) subjects did not have TB. The sensitivity, specificity, positive predictive value, and negative predictive value for active TB diagnosis by the T SPOT. TB were 83%, 71%, 81%, and 75%, respectively. For QFT-GIT, the sensitivity, specificity, positive predictive value, and negative predictive value for active TB diagnosis were 66%, 76%, 80%, and 62%, respectively. The QFT-GIT assay resulted in more indeterminate and false-negative results than the T-SPOT.TB assay, especially in immunocompromised patients. In conclusion, T-SPOT.TB had a higher sensitivity and resulted in fewer indeterminate results than the QFT-GIT assay for diagnosing active TB.