Table 1.
Xpert MTB/RIF assay performance for pulmonary and extrapulmonary specimens.
| Category | Specimen type | Number (%) | Xpert MTB/RIF Error& Invalid | True negative | False negative | True positive | False positive | Xpert Sensitivity (%) with 95% CI | Xpert Specificity (%) with 95% CI | Xpert Positive Predictive Value (%) with 95% CI | Xpert Negative Predictive Value (%) with 95% CI |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Pulmonary | BAL | 340 (16.5) | 4 | 327 | 0 | 3 | 6 | 100 (29.2–100) | 98.2 (29.2–100) | 33.3 (18.4–52.4) | 100 |
| Tracheal | 30 (1.4) | 0 | 29 | 0 | 1 | 0 | 100 (25–100) | 100 (88–100) | 100 | 100 | |
| Sputum | 848 (41.2) | 20 | 626 | 8 | 175 | 19 | 95.6 (91.5–98) | 97 (95.4–98.2) | 90.2 (85.5–93.4) | 98.7 (97.5–99.3) | |
| Extrapulmonary | Urine | 44 (2.1) | 2 | 40 | 0 | 2 | 1 | 100 (15.8–100) | 97.5 (86.8–99.9) | 66.6 (22.4–93.2) | 100 |
| Abscess | 49 (2.4) | 1 | 36 | 0 | 10 | 2 | 100 (69.1–100) | 94.7 (82.2–99.3) | 83.3 (56.4–95) | 100 | |
| Osteoarticular | 80 (3.4) | 2 | 66 | 2 | 3 | 7 | 60 (14.6–94.7) | 90.4 (81.2–96) | 30 (13.5–53.9) | 97 (91.8–98.9) | |
| Biopsy | 162 (7.8) | 9 | 119 | 5 | 13 | 16 | 72.2 (46.5–90.3) | 88.1 (81.4–93) | 44.8 (32–58.2) | 95.9 (91.8–98) | |
| Pericardium | 120 (5.8) | 2 | 112 | 3 | 2 | 1 | 40 (5.2–85.3) | 99.1 (95.1–99.9) | 66.6 (17.7–94.8) | 97.3 (94.8–98.7) | |
| Cerebrospinal fluid (CSF) | 44 (2.1) | 1 | 39 | 0 | 2 | 1 | 100 (15.8–100) | 97.5 (86.8–99.9) | 66.6 (22.4–93.2) | 100 | |
| Gastric Lavage | 111 (5.4) | 2 | 103 | 1 | 4 | 1 | 80 (28.3–99.4) | 99 (94.7–99.9) | 80 (35.1–96.7) | 99 (94.6–99.8) | |
| Blood | 15 (0.7) | 2 | 13 | 0 | 0 | 0 | — | 100 (75.2–100) | — | 100 | |
| Plural fluid | 175 (8.4) | 7 | 153 | 4 | 7 | 4 | 63.6 (30.7–89) | 97.4 (93.6–99.3) | 63.6 (37.6–83.5) | 97.4 (94.5–98.8) | |
| Ascites | 38 (1.8) | 2 | 33 | 0 | 3 | 0 | 100 (29.2–100) | 100 (89.4–100) | 100 | 100 | |
| Pulmonary | 1218 (59.2) | 24 | 982 | 8 | 179 | 25 | 95.7 (91.7–98.1) | 97.5 (96.3–98.3) | 87.7 (82.9–91.3) | 99.1 (98.4–99.5) | |
| Extrapulmonary | 838 (40.7) | 31 | 713 | 15 | 49 | 30 | 76.5 (64.3–86.2) | 95.9 (94.2–97.2) | 62 (52.8–70.4) | 97.9 (96.8–98.6) | |
| Total Number | 2056 | 55 | — | — | — | — | — | — | — | — | |