TABLE 9.
RISK STRATIFICATION OF TUBERCULOSIS EXPOSURE BY TEST AGREEMENT*
| Test Results | N | High Risk (5-mm criteria) | Moderate Risk (10-mm criteria) | Low Risk (15-mm criteria)† |
| All tests negative | 1,693 | 16 (1%) | 359 (21.2%) | 1,318 (77.9%) |
| One test positive | 68 | 4 (5.9%) | 33 (48.5%) | 31 (45.6%) |
| TST only | 32 | 2 (6.3%) | 23 (71.9%) | 7 (21.9%) |
| QFT-GIT only | 21 | 2 (9.5%) | 8 (38.1%) | 11 (52.4%) |
| T-Spot only | 15 | 0 (0%) | 2 (13.3%) | 13 (86.7%) |
| Two tests positive | 10 | 0 (0%) | 7 (70%) | 3 (30%) |
| TST and QFT-GIT | 1 | 0 (0%) | 1 (100%) | 0 (0%) |
| TST and T-Spot | 5 | 0 (0%) | 5 (100%) | 0 (0%) |
| QFT-GIT and T-Spot | 4 | 0 (0%) | 1 (25%) | 3 (75%) |
| All three tests positive | 10 | 1 (10%) | 7 (70%) | 2 (20%) |
Definition of abbreviations: QFT-GIT = QuantiFERON-TB Gold In-Tube test; T-Spot = T-SPOT.TB test; TST = tuberculin skin test.
*
Risk stratification as per Centers for Disease Control and Prevention risk stratified index (30).
†
χ2 (trend) for low risk compared with the other groups = 61.6; P < 0.0001.