Table 1. Diagnostic accuracy of the Xpert MTB/RIF test for detecting Mycobacterium tuberculosis and its resistance to rifampin.a .
| Variable | Detection of MTB | Detection of resistance to RIF |
|---|---|---|
| Sensitivity (%) | 100 (100-100) | 100 (100-100) |
| Specificity (%) | 94.5 (92.4-96.6) | 98.0 (94.2-101.8) |
| PPV (%) | 76.4 (68.3-84. 5) | 90.0 (76.0-103.1) |
| NPV (%) | 100 (100-100) | 100 (100-100) |
| Accuracy (%) | 95.3 (93.5-97.1) | 98.3 (95.1-101.6) |
| Kappa* | 0.84 (0.78-0.90) | 0.94 (0.82-1.06) |
MTB: Mycobacterium tuberculosis; RIF: rifampin; PPV: positive predictive value; and NPV: negative predictive value. aValues expressed as n (95% CI). *The criteria for kappa were as follows: < 0.20, poor; 0.21-0.40, weak; 0.41-0.60, moderate; 0.61-0.80, good; and > 0.80-1.00, very good.