Table 3.
Accuracy of Xpert Mycobacterium tuberculosis/Rifampicin and Smear on Nasopharyngeal Aspirates Compared With Liquid Culture
| NPA | Sensitivity | Specificity | PPV | NPV | Sensitivity for Smear-Positive Samples | Sensitivity for Smear-Negative Samples |
|---|---|---|---|---|---|---|
| All children with complete results from at least one IS and NPA specimen (n = 535) | ||||||
| Xpert | ||||||
| All | 49/87, 56.3 (45.7–67.0) | 440/448, 98.2 (97.0–99.5) | 86.0 | 92.1 | 27/30, 90.0 (78.6–100) | 22/57, 38.6 (25.6–51.6) |
| HIV infected (n = 117) | 10/15, 66.7 (39.6–93.7) | 100/102, 98.0 (95.3–100) | 83.0 | 95.2 | 8/9 88.9, (63.2–100) | 2/6 33.3, (0–87.5) |
| HIV uninfected (n = 417) | 39/72, 54.2 (42.4–66.0) | 339/345, 98.3 (96.9–99.6) | 91.1 | 86.7 | 19/21, 90.5 (76.8–100) | 20/51, 39.2 (25.3–53.1) |
| Smear | 21/87, 24.1 (15.0–33.3) | 448/448, 100 (99.2–100) | 100 | 87.2 | ||
| Children with complete results from two paired IS and NPA specimens (n = 396) | ||||||
| Xpert (first NPA specimen) | 30/63, 47.6 (34.9–60.3) | 329/333, 98.8 (97.6–100.0) | 88.2 | 90.9 | 15/16, 93.8 (80.4–100) | 15/47, 31.9 (18.1–45.7) |
| Xpert (both NPA specimens) | ||||||
| All | 41/63, 65.1 (53.0–77.2) | 327/333, 98.2 (96.8–99.6) | 87.2 | 93.7 | 16/16, 100 (79.4–100) | 25/47, 53.2 (38.4–68.0) |
| HIV infected (n = 80) | 8/8 100, (63.1–100) | 70/72, 97.2 (93.3–100) | 80 | 100 | 4/4, 100 (39.8–100) | 4/4, 100 (39.8–100) |
| HIV uninfected (n = 315) | 33/55, 60.0 (46.6–73.4) | 256/260, 98.5 (97.0–100.0) | 89.2 | 92.1 | 12/12, 100 (73.5–100) | 21/43, 48.8 (33.3–64.4) |
| Smear (two smears) | 16/63, 25.4 (14.3–36.4) | 333/333, 100 (98.9–100) | 100 | 87.7 | ||
Data are the number correct/number tested, % (95% confidence interval).
Abbreviations: HIV, human immunodeficiency virus; IS, induced sputum; NPA, nasopharyngeal aspirate; NPV, negative predictive value; PPV, positive predictive value.