Table 2 Qualitative and quantitative analysis of tuberculin skin test (TST) and interferon gamma release assay (IGRA) readouts in household contacts according to their TST status at study completion (8–12 weeks after enrollment)
Variable | All (N = 838) | TST-positive aat baseline (n = 523) | TST converters (n = 62) | OR 95% CI | P d | TST-negative (n = 253) | OR 95% CI | P e |
|---|---|---|---|---|---|---|---|---|
At Baseline | ||||||||
TST1 (mm) b | ||||||||
Median [IQR] | 13 [0–17] | 16 [14–19] | 0 [0–3] | 0 [0–2] | ||||
Mean [SD] | 11 {7.9} | 16 {3.7} | 1 {2.3] | − | − | 2 {2.9} | − | − |
Range | [0–30] | [10–30] | [0–8] | [0–9] | ||||
≥5 mm | 576 (69%) | − | − | − | ||||
≥10 mm | 523 (62%) | − | − | − | ||||
≥15 mm | 349 (42%) | − | − | − | ||||
At 8–12 weeks | ||||||||
Max TST (mm) c | ||||||||
Median [IQR] | 14 [8–18] | 16 [14–19] | 16 [12–20] | 0 [0–6] | ||||
Mean [SD] | 12 {7.3} | 16 {3.7} | 16 {5.2} | 0.98 (0.92–1.05) | 0.58 | 3 {4.3} | − | − |
Range | [0–30] | [10–30] | [0–25] | [0–17] | ||||
≥5 mm | 656 (78%) | − | − | − | ||||
≥ 10 mm | 607 (72%) | − | − | − | ||||
≥ 15 mm | 396 (47%) | − | − | − | ||||
IGRA (IU/mL) | ||||||||
Median [IQR] | 1.03 [0.03-8.6] | 4.4 [0.68–10] | 4.6 [0.07–10] | 0.02 [0–0.11] | ||||
Mean [SD] | 3.6 {4.2} | 5.1 {4.2} | 5.0 {4.6} | 1.01 (0.95-1.07) | 0.75 | 0.6 {1.9} | 1.42 (1.28-1.58) | <0.001 |
Range | [0–14] | [0–14] | [0–10] | [0–10] | ||||
Negative | 292 (41) | 78 (19) | 18 (31) | 1.92 (1.02–3.7) | 0.04 | 196 (84) | − | − |
Positive | 420 (59) | 343 (81) | 40 (69) | Ref | 37 (16) | |||