title: Diagnostic value of T-SPOT.TBinterferon-γ release assays for active tuberculosis.
abstract: The aim of the present study was to evaluate the diagnostic value of interferon-γ release assays for the detection of active tuberculosis (ATB) in patients previously vaccinated with Bacillus Calmette-Guérin (BCG). In total, 540 patients underwent the T-SPOT.TBtest, including 295 patients with active pulmonary TB (PTB), 52 patients with active extrapulmonary TB (EPTB), 11 individuals with inactive TB and 182 non-TB cases. Simultaneously, 186 patients with ATB, including PTB and EPTB cases, and 125 non-TB patients underwent tuberculin skin tests (TST). Associations between the sensitivity of the T-SPOT.TBassays and lung lesion severity, positive smear grade, disease site and the duration of anti-TB treatment were evaluated. The sensitivity and specificity values of the T-SPOT.TBassay for diagnosing ATB were 76.66 and 76.37%, respectively, and the positive rate in the inactive TB test results was significantly lower (23.63%; P<0.001). The diagnostic sensitivity was higher in the PTB cases when compared with the EPTB cases (P=0.01). Furthermore, the diagnostic sensitivity of the ATB cases undergoing anti-TB treatment was significantly lower when compared with the cases not undergoing treatment (P=0.002), and the sensitivity gradually decreased with the treatment duration (P=0.01). In addition, a statistically significant difference was identified in the specificity between the T-SPOT.TBassay and the TST (76.37 vs. 51.15%; P<0.001), whereas the sensitivity values did not differ significantly (76.66 vs. 75.56%). Therefore, the results indicated that the T-SPOT.TBassay is a promising diagnostic test for active PTB in a BCG-vaccinated population, and should replace the TST. As the administration of anti-TB treatment resulted in a lower sensitivity to the diagnostic test, the T-SPOT.TBassay may also be suitable for the assessment of treatment outcomes.
authors.affiliation: Department of Tuberculosis, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai 200433, P.R. China.
authors.forename: Liping
authors.initials: L
authors.lastname: Yan
authors.affiliation: Department of Tuberculosis, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai 200433, P.R. China.
authors.forename: Heping
authors.initials: H
authors.lastname: Xiao
authors.affiliation: Department of Tuberculosis, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai 200433, P.R. China.
authors.forename: Min
authors.initials: M
authors.lastname: Han
authors.affiliation: Department of Tuberculosis, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai 200433, P.R. China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhang
keywords: T-SPOT.TB; extrapulmonary tuberculosis; interferon-γ release assays; pulmonary tuberculosis; tuberculin skin test