TABLE 2.
Sensitivity and specificity for TB detection against the culture reference standard
| Comparisona | % sensitivity (95% CI; n/N)b |
% specificity (95% CI; n/N)c |
|||
|---|---|---|---|---|---|
| Any culture positive | Smear negative, culture positive | HIV negative | HIV positive | All cultures negative | |
| Same sputum | |||||
| S2 Xpert Ultra | 91 (85 to 95; 116/127) | 59 (41 to 75; 16/27) | 92 (85 to 96; 83/90) | 89 (75 to 96; 33/37) | 98 (96 to 99; 296/301) |
| S2 RT-MTB | 77 (69 to 84; 98/127) | 22 (11 to 41; 6/27) | 81 (72 to 88; 73/90) | 68 (51 to 80; 25/37) | 98 (95 to 99; 294/301) |
| Difference (Xpert Ultra minus RT-MTB) | +14 (+9.2 to +21; 18/127) | +37 (+20 to +56; 10/27) | +11 (+6.1 to +19; 10/90) | +22 (+10 to +37; 8/37) | +0.7 (−1.4 to +2.9); 3/301 |
| Across sputum | |||||
| S1 Xpert | 88 (80 to 93; 82/93) | 45 (26 to 66; 9/20) | 88 (79 to 94; 66/75) | 89 (67 to 97; 16/18) | 100 (97 to 100; 213/214) |
| S1 Xpert Ultra | 89 (81 to 94; 83/93) | 50 (30 to 70; 10/20) | 89 (80 to 94; 67/75) | 89 (67 to 97; 16/18) | 100 (97 to 100; 213/214) |
| S4 RT-MTB | 80 (70 to 87; 74/93) | 20 (8 to 42; 4/20) | 81 (71 to 89; 61/75) | 72 (49 to 88; 13/18) | 98 (95 to 99; 209/214) |
| Difference (Xpert minus RT-MTB) | +8.6 (+2.4 to +17; 8/93) | +25 (−1.1 to +49; 5/20) | +6.7 (+0.0 to +15; 5/75) | 16 (−3.9 to +39; 3/18) | +1.9 (−1.8 to +2.9; 4/214) |
| Difference (Xpert Ultra minus RT-MTB) | +10 (+3.3 to +18; 9/93) | 30 (2.7 to 54; 6/20) | 8.0 (+0.1 to +17; 6/75) | +16 (−3.9 to +39; 3/18) | +1.9 (−1.8 to +2.9; 4/214) |
a
S2, sputum 2; S1, sputum 1; S4, sputum 4.
b
n/N, true positive/(true positive + false negative).
c
n/N, true negative/(true negative + false positive).