Table 5.
Validity of Predictors of Latent Tuberculosis Infection, as Measured by the T-SPOT.TB (T-Spot), Among US Army Recruits
| Factor | No. (%) of positive RFQ responses (n = 1783) | No. of persons with positive T-Spot results (n = 34) | RFQ sensitivity, % | RFQ specificity, % | RFQ PPV, % | RFQ NPV, % | RFQ AUC |
| 1. Close contact of TB case | 20 (1.1) | 3 | 2.9 | 98.9 | 5.0 | 98.1 | 0.509 |
| 2. TB prevalence ≥20 cases per 100000 persons in country of birth | 96 (5.4) | 10 | 29.4 | 95.1 | 10.4 | 98.6 | 0.623 |
| 3. Lived with parent born outside of the US | 79 (4.4) | 7 | 20.6 | 95.9 | 8.9 | 98.4 | 0.582 |
| 4. Prior positive TST result | 21 (1.2) | 5 | 14.7 | 99.1 | 23.8 | 98.4 | 0.569 |
| 5. Age ≥30 years | 149 (8.4) | 8 | 23.5 | 91.9 | 5.4 | 98.4 | 0.577 |
| Combinations of factors | |||||||
| 1 or 2 | 113 (6.3) | 11 | 32.4 | 94.2 | 9.7 | 98.6 | 0.633 |
| 1, 2, or 3 | 124 (7.0) | 12 | 35.3 | 93.6 | 9.7 | 98.7 | 0.667 |
| 1, 2, 3, or 4 (selected model) | 166 (9.3) | 15 | 44.1 | 91.4 | 9.0 | 98.8 | 0.688 |
| 1, 2, 3, 4, or 5 | 282 (15.8) | 18 | 52.9 | 84.9 | 6.4 | 98.9 | 0.708 |
| 1, 2, 3, 4, 5, or overseas travel ≥1 month | 318 (17.8) | 18 | 52.9 | 82.9 | 5.7 | 98.9 | 0.712 |
| 1, 2, 3, 4, 5, or residence in congregate setting | 367 (20.6) | 19 | 55.9 | 80.1 | 5.2 | 98.9 | 0.711 |
| Any risk factora | 579 (32.5) | 21 | 61.8 | 68.1 | 3.6 | 98.9 | 0.744 |
NOTE. AUC, area under the curve; NPV, negative predictive value; PPV, positive predictive value; RFQ, risk factor questionnaire; TB, tuberculosis; T-Spot, T-SPOT®.TB.
a
Risk factors include all of the previously mentioned risk factors, plus health care work, casual contact with a TB case, and prior TB treatment.