Table 4.
True- and false-positive resultsa when changing from QFT-IT to T-Spot in screening for LTBI
| Country | LTBI prevalenceb | Increase in true positivesa,c | Increase in false positivesa,c | Increase in false positives for every true positive gained |
|---|---|---|---|---|
| United States |
4.70% |
329 |
12,389 |
37.7 |
| Mexico |
28.82% |
2,018 |
9,253 |
4.6 |
| Brazil |
38.74% |
2,712 |
7,964 |
2.9 |
| Thailand |
46.74% |
3,272 |
6,924 |
2.1 |
| Ivory Coast | 54.62% | 3,823 | 5,900 | 1.5 |
LTBI, latent tuberculosis infection; QFT-IT, QuantiFERON-TB Gold In-Tube; T-Spot, T-SPOT.TB.
a Based on a hypothetical population of 100,000 tested individuals.
b Source: World Health Organization Global TB Database [4].
c Sensitivity estimates: QFT-IT 81%, T-Spot 88%; specificity estimates: QFT-IT 99%, T-Spot 86%.