Table 5. Test results in validation cohort, patients with confirmed active TB (n = 68) and endemic controls (n = 35) from Tanzania.
| QFT (IFN-γ) | QFT (IP-10) | ESAT-6 free IGRA (IFN-γ) | ESAT-6 free IGRA (IP-10) | ||
|---|---|---|---|---|---|
| Patients (n = 68) | Positive | 54 (79) | 54 (79) | 56 (84) | 50 (74) |
| Negative | 12 (20) | 12 (20) | 11 (16) | 17 (25) | |
| Indeterminate | 1 (1) | 1 (1) | 1 (1) | 1 (1) | |
| Endemic controls (n = 35) | Positive | 17 (49) | 15 (43) | 17 (49) | 13 (37)* |
| Negative | 18 (51) | 20 (57) | 18 (51) | 22 (63) | |
| Indeterminate | 0 (0) | 0 (0) | 0 (0) | 0 (0) |
IFN-γ and IP-10 levels were determined using ELISA and deemed positive, negative and indeterminate using cut offs determined in a training set 0.25 IU/ml for ESAT-6 free IGRA (IFN-γ), 1.0 ng/ml for ESAT-6 free IGRA (IP-10) and 1.3 for QFT (IP-10). *p = 0.046, McNemars test compared to QFT (IFN-γ), all other comparisons to QFT (IFN-γ) were non-significant.