Table 3 Sensitivity, specificity, and Predictive values of AFB smear and Xpert MTB/RIF assay using culture as a gold standard
Method and test type | Sensitivity %(95 % CI) | Specificity %(95 % CI) | PPV %(95 % CI) | NPV %(95 % CI) |
|---|---|---|---|---|
AFB Smear | 36.2 (23.8–48.6) | 99 4 (98.2–100) | 95.5 (86.8–100) | 81.3 (75.9–86.7) |
GeneXpert MTB/RIF assay | ||||
Smear negative | 48.6(32.5–64.8) | 96.9(94.2–99.6) | 78.3(61.4–95.1) | 89.1(84.5–93.8) |
Smear positive | 95.2(86–100) | N/Aa | 95.2(86–100) | N/A |
Total (SPTB & SNTB) | 65.5(53.3–77.7) | 96.3 (93.4–992) | 86.4(76.2–96.5) | 88.6(83.9–93.3) |