Table 2.
Sensitivity, Specificity, Positive Predictive Values, and Negative Predictive Values during 3 Years’ Follow-up with Prespecified Test Thresholds
| QFT-GIT (IU/ml) |
T-SPOT.TB (Spots) |
BCG-adjusted TST* (mm) |
|||||||
|---|---|---|---|---|---|---|---|---|---|
| ≥0.35 | ≥0.7 | ≥4 | ≥5 | ≥8 | ≥50 | ≥5 | ≥10 | ≥15 | |
| Sensitivity | |||||||||
| n | 50 | 44 | 19 | 53 | 50 | 22 | 62 | 42 | 25 |
| N | 82 | 82 | 82 | 81 | 81 | 81 | 89 | 89 | 89 |
| Estimate, % | 61.0 | 53.7 | 23.2 | 65.4 | 61.7 | 27.2 | 69.7 | 47.2 | 28.1 |
| 95% CI | 49.6–71.6 | 42.3–64.7 | 14.6–33.8 | 54–75.7 | 50.3–72.3 | 17.9–38.2 | 59–79 | 36.5–58.1 | 19.1–38.6 |
| Specificity | |||||||||
| n | 6,134 | 6,511 | 7,242 | 5,856 | 6,155 | 6,948 | 5,520 | 6,295 | 6,882 |
| N | 7,755 | 7,755 | 7,755 | 7,363 | 7,363 | 7,363 | 7,445 | 7,445 | 7,445 |
| Estimate, % | 79.1 | 84.0 | 93.4 | 79.5 | 83.6 | 94.4 | 74.1 | 84.6 | 92.4 |
| 95% CI | 78.2–80 | 83.1–84.8 | 92.8–93.9 | 78.6–80.4 | 82.7–84.4 | 93.8–94.9 | 73.1–75.1 | 83.7–85.4 | 91.8–93 |
| Positive predictive value | |||||||||
| n | 50 | 44 | 19 | 53 | 50 | 22 | 62 | 42 | 25 |
| N | 1,671 | 1,288 | 532 | 1,560 | 1,258 | 437 | 1,987 | 1,192 | 588 |
| Estimate, % | 3.0 | 3.4 | 3.6 | 3.4 | 4.0 | 5.0 | 3.1 | 3.5 | 4.3 |
| 95% CI | 2.2–3.9 | 2.5–4.6 | 2.2–5.5 | 2.6–4.4 | 3–5.2 | 3.2–7.5 | 2.4–4 | 2.6–4.7 | 2.8–6.2 |
| Negative predictive value | |||||||||
| n | 6,134 | 6,511 | 7,242 | 5,856 | 6,155 | 6,948 | 5,520 | 6,295 | 6,882 |
| N | 6,166 | 6,549 | 7,305 | 5,884 | 6,186 | 7,007 | 5,547 | 6,342 | 6,946 |
| Estimate, % | 99.5 | 99.4 | 99.1 | 99.5 | 99.5 | 99.2 | 99.5 | 99.3 | 99.1 |
| 95% CI | 99.3–99.6 | 99.2–99.6 | 98.9–99.3 | 99.3–99.7 | 99.3–99.7 | 98.9–99.4 | 99.3–99.7 | 99–99.5 | 98.8–99.3 |
Definition of abbreviations: BCG = bacillus Calmette-Guérin; CI = confidence interval; n = numerator; N = denominator; QFT-GIT = QuantiFERON Gold-In-Tube; TB = tuberculosis; TST = tuberculin skin test.
*
For participants with previous BCG vaccination (defined by self-report and scar inspection), 10 mm was deducted from the quantitative TST result to adjust for the associated sensitization to BCG (“BCG-adjusted TST”).