TABLE 3.
Diagnostic test performances of smear microscopy, the Xpert MTB/RIF assay, digital radiography, and TB symptomsd
| Test or result | Performance (%) (95% CI), no. of positive participants/total no. of participants tested |
Cohen’s κ | |||
|---|---|---|---|---|---|
| Sensitivity | Specificity | PPV | NPV | ||
| Smear microscopy | 20.00 (8.07–41.60), 4/20 | 99.94 (99.63–99.99), 1,543/1,544 | 80.00 (37.56–96.38), 4/5 | 98.97 (98.34–99.37), 1,543/1,559 | 0.317 |
| Xpert MTB/RIF | 80.00 (58.40–91.93), 16/20 | 99.87 (99.53–99.96), 1,542/1,544 | 88.89 (67.20–96.90), 16/18 | 99.74 (99.34–99.90), 1,542/1,546 | 0.840 |
| Chest radiography | 45.00 (25.82–65.79), 9/20 | 95.98 (94.89–96.85), 1,482/1,544 | 12.68 (6.82–22.37), 9/71 | 99.26 (98.69–99.59), 1,482/1,493 | 0.182 |
| TB symptoms | 5.00 (0.88–23.61), 1/20 | 98.83 (98.16–99.26), 1,526/1,544 | 5.26 (0.93–24.64), 1/19 | 98.77 (98.09–99.21), 1,526/1,545 | 0.039 |
| TB symptom positive or chest radiography positivea | 45.00 (25.82–65.79), 9/20 | 95.92 (94.81–96.80), 1,481/1,544 | 12.50 (6.72–22.08), 9/72 | 99.26 (98.68–99.59), 1,481/1,492 | 0.179 |
| Smear microscopy positive or Xpert MTB/RIF assay positive | 80.00 (58.40–91.93), 16/20 | 99.81 (99.43–99.93), 1,541/1,544 | 84.21 (62.44–94.48), 16/19 | 99.74 (99.34–99.90), 1,541/1,545 | 0.818 |
| Smear microscopy positive or chest radiography positive | 60.00 (38.66–78.12), 12/20 | 95.92 (94.81–96.80), 1,481/1,544 | 16.00 (9.40–25.92), 12/75 | 99.46 (98.94–99.73), 1,481/1,489 | 0.237 |
| Xpert MTB/RIF positive or chest radiography positive | 90.00 (69.90–97.21), 18/20 | 95.98 (94.89–96.85), 1,482/1,544 | 22.50 (14.73–32.79), 18/80 | 99.87 (99.51–99.96), 1,482/1,484 | 0.347 |
| Smear microscopy positive, Xpert MTB/RIF assay positive, or chest radiography positive | 90.00 (69.90–97.21), 18/20 | 95.92 (94.81–96.80), 1,481/1,544 | 22.22 (14.54–32.41), 18/81 | 99.87 (99.51–99.96), 1,481/1,483 | 0.343 |
| Smear microscopy followed by Xpert MTB/RIFb | 80.00 (58.40–91.93), 16/20 | 99.81 (99.43–99.93), 1,541/1,544 | 84.24 (62.44–94.48), 16/19 | 99.74 (99.34–99.90), 1,541/1,545 | 0.818 |
| Smear microscopy followed by chest radiography and symptomsb followed by Xpert MTB/RIF assayc | 50.00 (29.93–70.07), 10/20 | 99.81 (99.43–99.93), 1,541/1,544 | 76.92 (49.75–91.82), 10/13 | 99.36 (98.82–99.65), 1,541/1,551 | 0.602 |
| Chest radiography and symptoms followed by Xpert MTB/RIF assayc | 35.00 (18.12–56.17), 7/20 | 99.87 (99.53–99.96), 1,542/1,544 | 77.78 (45.26–93.68), 7/9 | 99.16 (98.57–99.51), 1,542/1,555 | 0.479 |
| Chest radiography and symptoms followed by smear microscopyc followed by Xpert MTB/RIF assayb | 35.00 (18.12–56.17), 7/20 | 99.87 (99.53–99.96), 1,542/1,544 | 77.78 (45.26–93.68), 7/9 | 99.16 (98.57–99.51), 1,542/1,555 | 0.479 |
a
WHO-recommended algorithm.
b
Performed if smear negative.
c
Performed if digital radiography results were compatible with active TB or TB symptoms.
d
CI, confidence interval; PPV, positive predictive value; NPV, negative predictive value.