Table 3.
Tuberculosis Incidence among Participants According to QuantiFERON Status
| Events (n) | Observation Time (Person-Years) | Rate/100 Person-Years | 95% CI | |
|---|---|---|---|---|
| QFT | ||||
| All negative QFT | 7 | 3,994.6 | 0.18 | 0.07–0.36 |
| All positive QFT | 46 | 4,371.7 | 1.05 | 0.77–1.40 |
| Baseline QFT positive | 57 | 5,854.7 | 0.97 | 0.74–1.26 |
| QFT conversion | 17 | 1,223.1 | 1.39 | 0.81–2.22 |
| QFT reversion | 3 | 203.9 | 1.47 | 0.30–4.30 |
| TST | ||||
| All negative TST | 3 | 3,502.5 | 0.09 | 0.01–0.25 |
| Baseline positive TST* | 58 | 6,519.1 | 0.89 | 0.67–1.15 |
| TST conversion | 7 | 654.3 | 1.07 | 0.43–2.22 |
| TST reversion | 0 | 235.7 | 0.00 | 0.00–1.58 |
| Both | ||||
| All negative QFT/TST | 2 | 2,827.2 | 0.07 | 0.01–0.26 |
| Baseline QFT/TST positive | 47 | 4,642.3 | 1.01 | 0.74–1.35 |
| QFT/TST conversion | 7 | 525.9 | 1.33 | 0.53–2.76 |
Definition of abbreviations: CI = confidence interval; QFT = QuantiFERON-TB Gold In-Tube test; TST = tuberculin skin test.
*
Participants who developed active tuberculosis did not have TST subsequently performed, and therefore an unbiased all-positive TST group could not be assessed.