TABLE 8.

RISK STRATIFICATION OF TUBERCULOSIS EXPOSURE BY QUANTITATIVE RESULT OF TST, QFT-GIT, AND T-SPOT^*

		Quantitative TST Result				Quantitative QFT-GIT Result			Quantitative T-Spot Result
Risk Stratification†	N	0–4 mm	5–9 mm	10–14 mm	≥15 mm‡	<0.35	0.35–0.99	≥1§	≤4 Spots	5–7 Spots	≥8 Spots||
High risk (5-mm criteria)	21	18 (85.7%)	1 (4.8%)	1 (4.8%)	1 (4.8%)	18 (85.7%)	2 (9.5%)	1 (4.8%)	20 (95.2%)	0	1 (4.8%)
Moderate risk (10-mm criteria)	409	362 (88.5%)	10 (2.4%)	21 (5.1%)	16 (3.9%)	392 (95.8%)	7 (1.7%)	10 (2.4%)	391 (95.6%)	3 (0.7%)	15 (3.7%)
Low risk (15-mm criteria)	1,373	1,332 (97%)	21 (1.5%)	10 (0.7%)	10 (0.7%)	1,356 (98.8%)	13 (1%)	4 (0.3%)	1,336 (97.3%)	19 (1.4%)	18 (1.3%)

Definition of abbreviations: QFT-GIT = QuantiFERON-TB Gold In-Tube test; T-Spot = T-SPOT.TB test; TST = tuberculin skin test.

^*Note: The 22 borderline T-Spot results were added into this analysis to have results for the five to seven spots category.

^†Risk stratification as per Centers for Disease Control and Prevention risk stratified index (30).

^‡χ² (trend) for 15 mm compared with the other groups = 24.6; P < 0.0001.

^§χ² (trend) for 1 compared with the other groups = 24.4; P < 0.0001.

^||χ² (trend) for 8 spots compared with the other groups = 11.5; P = 0.0007.