Table 2.
The diagnostic performance of AFB, culture, pathological examination, Xpert and Ultra, using culture or final diagnosis as gold-standard
| Method | % (correct no./total no.) 95% CI | ||||
|---|---|---|---|---|---|
| Sensitivity | Specificity | PPV | NPV | ||
| For culture-positive TB patients (n = 11) | AFB |
63.6 (7/11) 31.6–87.6 |
100 (47/47) 90.6–100 |
100 (7/7) 56.1–100 |
92.2 (47/51) 80.3–97.5 |
| Pathology |
72.7 (8/11) 39.3–92.7 |
85.1 (40/47) 71.1–93.3 |
53.3 (8/15) 27.4–77.8 |
93.0 (40/43) 79.9–98.2 |
|
| Xpert |
90.9 (10/11) 57.1–99.5 |
89.4 (42/47) 76.1–96.0 |
66.7 (10/15) 38.7–87.0 |
97.7 (42/43) 86.2–99.9 |
|
| Ultra |
90.9 (10/11) 57.1–99.5 |
59.6 (28/47) 44.3–73.3 |
34.5 (10/29) 18.6–54.3 |
96.6 (28/29) 80.4–99.8 |
|
| For culture-positive and negative TB patients (n = 96) | AFB |
8.3 (8/96) 3.9–16.2 |
100 (47/47) 90.6–100 |
100 (8/8) 59.8–100 |
34.8 (47/135) 27.0–43.5 |
| Culture |
11.5 (11/96) 6.1–20.0 |
100 (47/47) 90.6–100 |
100 (11/11) 67.9–100 |
35.6 (47/132) 27.6–44.5 |
|
| Pathology |
42.7 (41/96) 32.8–53.2 |
85.1 (40/47) 71.1–93.3 |
85.4 (41/48) 72.8–92.8 |
42.1 (40/95) 32.2–52.7 |
|
| Xpert |
64.6 (62/96)a 54.1–73.9 |
89.4 (42/47) 76.1–96.0 |
92.5 (62/67) 86.1–99.0 |
55.3 (42/76) 43.8–66.7 |
|
| Ultra |
78.1 (75/96)a 68.3–85.7 |
59.6 (28/47) 44.3–73.3 |
79.8 (75/94) 71.5–88.1 |
57.1 (28/49) 42.8–71.5 |
|
SE sensitivity, SP specificity, PPV positive predictive value, NPV negative predictive value
aMcNemar test P = 0.011 (Ultra vs. Xpert)