TABLE 6.
ASSOCIATIONS BETWEEN SELECTED CHARACTERISTICS AND DISCORDANCE BETWEEN POSITIVE TST (≥10 MM) AND NEGATIVE IGRA
| Recruits with a Negative QFT-GIT Result (n = 1,745) |
Recruits with a Negative T-Spot Result (n = 1,747) |
|||||||
| Characteristic | N (of 1,745) | N with TST Positive* (n = 37) | Bivariate Prevalence Ratio (95% CI) | Multivariate Prevalence Ratio (95% CI) | N (of 1,747) | N with TST Positive* (n = 33) | Bivariate Prevalence Ratio (95% CI) | Multivariate Prevalence Ratio (95% CI) |
| Age, yr† | — | — | 1.1 (1.1–1.2) | ‡ | — | — | 1.1 (1.1–1.2) | ‡ |
| Sex | ‡ | ‡ | ||||||
| Male | 1,136 | 21 | 1 (REF) | 1,132 | 19 | 1 (REF) | ||
| Female | 607 | 16 | 1.4 (0.7–2.7) | 613 | 14 | 1.4 (0.7–2.7) | ||
| Race and ethnic group | ‡ | ‡ | ||||||
| White | 1,158 | 11 | 1 (REF) | 1,157 | 11 | 1 (REF) | ||
| Black | 397 | 10 | 2.7 (1.1–6.2) | 400 | 10 | 2.6 (1.1–6.1) | ||
| Asian/Pacific Islander | 60 | 12 | 21.1 (9.7–45.7) | 59 | 8 | 14.2 (6–34.1) | ||
| Hispanic | 194 | 7 | 3.8 (1.5–9.7) | 197 | 7 | 3.7 (1.5–9.5) | ||
| TB prevalence in country of birth or long-term residence | ||||||||
| <20 per 100,000 | 1,659 | 19 | 1 (REF) | 1 (REF) | 1,662 | 18 | 1 (REF) | 1 (REF) |
| 20–100 per 100,000 | 30 | 3 | 8.7 (2.7–27.9) | 6.2 (2.1–18.7) | 30 | 3 | 9.2 (2.9–29.7) | 7.9 (2.8–22.5) |
| >100 per 100,000 | 56 | 15 | 23.3 (12.6–43.6) | 7.7 (3–20.1) | 55 | 12 | 20.1 (10.2–39.7) | 9.1 (3.9–21.4) |
| BCG vaccination | ||||||||
| No | 1,690 | 20 | 1 (REF) | 1 (REF) | 1,695 | 19 | 1 (REF) | 1 (REF) |
| Yes | 55 | 17 | 26.1 (14.5–47) | 4 (1.6–9.7) | 52 | 14 | 24 (12.8–45.2) | 4.4 (2.1–9.5) |
| BST reaction | ||||||||
| 0–4 mm | 1,417 | 8 | 1 (REF) | 1 (REF) | 1,423 | 7 | 1 (REF) | 1 (REF) |
| 5–9 mm | 133 | 7 | 9.3 (3.4–25.3) | 5.5 (2.2–13.5) | 132 | 6 | 9.2 (3.2–27.1) | 5.4 (2–14.5) |
| 10–14 mm | 145 | 11 | 13.4 (5.5–32.9) | 6 (2.3–15.5) | 142 | 9 | 12.9 (4.9–34.1) | 5.2 (1.9–14.2) |
| 15–19 mm | 34 | 4 | 20.8 (6.6–65.9) | 15.6 (5.1–47.5) | 35 | 5 | 29 (9.7–87) | 14.5 (4.8–43.5) |
| 20+ mm | 16 | 7 | 77.5 (31.9–188) | 37.5 (11–128) | 15 | 6 | 81.3 (31–213) | 86.1 (32.6–227) |
| Region of birth | ‡ | ‡ | ||||||
| NE | 295 | 7 | 1 (REF) | 297 | 7 | 1 (REF) | ||
| SE | 591 | 9 | 0.6 (0.2–1.7) | 590 | 9 | 0.6 (0.2–1.7) | ||
| West | 613 | 10 | 0.7 (0.3–1.8) | 614 | 9 | 0.6 (0.2–1.7) | ||
| Other | 246 | 11 | 1.9 (0.7–4.8) | 246 | 8 | 1.4 (0.5–3.8) | ||
| Farm work | ‡ | ‡ | ||||||
| No | 1,401 | 34 | 1 (REF) | 1,406 | 3 | 1 (REF) | ||
| Yes | 344 | 3 | 0.4 (0.1–1.2) | 341 | 30 | 0.4 (0.1–1.3) | ||
Definition of abbreviations: BCG = bacille Calmette-Guérin vaccine; BST = Battey skin test; CI = confidence interval; IGRA = IFN-γ release assay; QFT-GIT = QuantiFERON-TB Gold In-Tube test; TB = tuberculosis; T-Spot = T-SPOT.TB test; TST = tuberculin skin test.
*
TST positive defined by risk stratified interpretation (30).
†
Age was modeled as a continuous variable and all observations were used in the analysis; all others were categorical.
‡
Multivariate models did not include variables with P > 0.05.