Table 4.
Sensitivity, specificity, PPV and NPV to detect tuberculosis (TB) infection and rifampicin resistance based on a culture method as a gold standard
| Method | Sensitivity | Specificity | PPV | NPV | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| % (n) |
95% CI | % (n) |
95% CI | % (n) |
95% CI | % (n) |
95% CI | ||||
| Detection of TB infection | |||||||||||
| Microscopy | 70.2 | 63.9–76.0 | 71.4 | 57.8–82.7 | 90.6 | 85.5–94.5 | 33.9 | 25.4–43.2 | |||
| (165/235) | (40/56) | (165/182) | (40/118) | ||||||||
| Xpert MTB/RIF | 81.3 | 75.7–86.1 | 98.2 | 90.4–99.9 | 97.9 | 94.8–99.4 | 57.3 | 46.8–67.3 | |||
| (191/235) | (55/56) | (191/195) | (55/96) | ||||||||
| Detection of rifampicin resistance | |||||||||||
| Xpert MTB/RIF | 96.8 | 90.9–99.3 | 91.8 | 84.4–96.4 | 94.8 | 88.3–98.3 | 97.8 | 92.3–99.7 | |||
| (91/94) | (89/97) | (91/96) | (89/91) | ||||||||
PPV = positive predictive value, NPV = negative predictive value, CI = confidence interval