Table 3.
Analysis of effectiveness of each screening strategy
| Effectiveness Measures | TST | T-SPOT.TB | QFT-GIT | TST/T-SPOT.TB | TST/QFT-GIT |
|---|---|---|---|---|---|
| Numbers of post-primary TB cases in 2 year period | 4.52 | 3.80 | 4.03 | 4.67 | 4.85 |
| Number of TB cases prevented by screening strategy | 2.98 | 3.70 | 3.47 | 2.83 | 2.65 |
| Numbers of people treated for LTBI | 284 | 228 | 242 | 174 | 168 |
| Numbers of true positives treated | 184 | 228 | 214 | 174 | 163 |
| Numbers of false positives treated | 101 | 0 | 28 | 0 | 5 |
| Numbers of people treated for LTBI per case of active TB prevented (NNT) | 95.5 | 61.7 | 69.7 | 61.7 | 63.6 |
Effectiveness measures relate to outcomes and costs for entire cohort of 1,000 contacts over the 2 year examination period. No screening results in 7.5 cases of post-primary TB in the 2 year period. (TST - Tuberculin Skin Test, QFT-GIT - Quantiferon-TB Gold-In-Tube, NNT- number needed to treat)