TABLE 1

QuantiFERON-TB Plus (QFT-Plus) performance characteristics in different study groups

FrequencyQFT-Plus resultPositive results in each tubeIFN-γ concentration IU·mL−1TB2−TB1 IU·mL−1
IndeterminateNegative#Positive#TB1TB2TB1TB2
Low-risk controls1060103 (97.17)3 (2.83)210.1 (0.09–0.13)0.11 (0.09–0.13)0 (−0.01–0.01)
Active TB119314 (12.07)102 (87.93)961012.09 (0.83–6.52)2.88 (1–7.89)0.14 (−0.13–0.79)
Sex
 Male7217 (9.86)64 (90.14)59642.08 (0.86–6.38)2.91 (1.17–7.62)0.23 (−0.14–0.88)
 Female4727 (15.56)38 (84.44)37372.09 (0.71–7.03)2.85 (0.88–7.80)0.11 (−0.11–0.50)
Smear
 Negative65112 (18.75)52 (81.25)51522.12 (0.89–9.51)2.69 (1.01–9.66)0.05 (−0.17–0.55)
 Positive5422 (3.85)50 (96.15)45492 (0.67–6.04)3.26 (0.92–6.31)0.29 (0–1.16)
Localisation
 PTB7939 (11.84)67 (88.16)62661.93 (0.57–6.04)2.82 (0.75–6.22)0.26 (−0.12–0.80)
 EPTB4005 (12.5)35 (87.5)34352.29 (1.23–10)2.95 (1.15–10)0.06 (−0.17–0.46)
BCG
 Negative602 (33.33)4 (66.67)441.15 (0.33–1.86)1.47 (0.4–2.75)0.07 (0.01–0.44)
 Positive5404 (7.41)50 (92.59)44502.01 (0.9–6.57)2.79 (1.02–8.2)0.14 (−0.20–0.65)
  • Data are presented as n, n (%) or median (interquartile range). IFN: interferon; TB: tuberculosis; PTB: pulmonary tuberculosis; EPTB: extrapulmonary tuberculosis; BCG: bacille Calmette–Guérin. #: percentages are based on the total number of valid tests, excluding indeterminate results.