Evaluation of interferon gamma release assay in the diagnosis of pulmonary tuberculosis

Abstract

Objective To evaluate the value of interferon gamma release assay, QuantiFERON-TB Gold In-Tube (QFT-GIT) in the diagnosis of pulmonary tuberculosis. Methods From June 2012 to December 2014, a prospective study was undertaken at Beijing Chest Hospital, Capital Medical University.A total of 593 patients with suspected pulmonary tuberculosis [human immunodeficiency virus (HIV) negative, age≥ 16 years old] were enrolled and 84 (14.2%) patients were excluded for uncertain diagnosis.Of the 509 patients were divided into two groups: 322 tuberculosis (including 229 bacteriological-negative TB) and 263 non-tuberculosis groups.Each patient was tested by QFT-GIT on peripheral blood and the diagnostic performance of QFT-GIT in pulmonary tuberculosis were analyzed according to the final diagnosis. Results Of 22 patients (4.3%) with indeterminate test results, age was associated with the rate of indeterminate test results.The positive rate of QFT-GIT in bacteriological-positive and bacteriological-negative pulmonary tuberculosis were 89.0% and 81.9%, there was no significant difference between them (χ2=2.384, P>0.05). The sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio and negative likelihood ratio of the QFT-GIT were 84.0%, 62.2%, 79.1%, 69.6%, 2.23 and 0.257, respectively. Conclusions QFT-GIT may be a more accurate approach for the diagnosis of active tuberculosis, offers more basis for the diagnosis of smear negative tuberculosis. Key words: Mycobacterium tuberculosis; Interferon gamma release assay; Enzyme-linked immunosorbent assay; Diagnostic performance