Table 1.
Demographic and behavioral characteristics of participants with negative QFT results (IFN-γ < 0.35 IU/mL) at baseline, included versus not included in the analysis; Tijuana, Mexico, 2006–2008.
| Characteristic | Included | Not included | P value* |
|---|---|---|---|
| N = 129 | N = 212 | ||
| n (%) | n (%) | ||
| Gender | 0.806 | ||
| Male | 107 (82.9) | 178 (84.0) | |
| Female | 22 (17.1) | 34 (16.0) | |
| Age, median (IQR) | 38 (32–43) | 37 (30–42) | 0.247 |
| Education | 0.389 | ||
| Up to primary | 39 (30.2) | 76 (35.8) | |
| Primary to middle | 60 (46.5) | 83 (39.2) | |
| High school and higher | 30 (23.3) | 53 (25.0) | |
| Unstable housing | 0.357 | ||
| No | 113 (87.6) | 178 (84.0) | |
| Yes | 16 (12.4) | 34 (16.0) | |
| History of incarceration | 0.719 | ||
| No | 78 (60.5) | 124 (58.5) | |
| Yes | 51 (39.5) | 88 (41.5) | |
| HIV infection | 0.366 | ||
| No | 123 (95.3) | 197 (92.9) | |
| Yes | 6 (4.7) | 15 (7.1) | |
| Alcohol | 0.154 | ||
| None | 76 (58.9) | 134 (63.2) | |
| Less than twice per week | 31 (24.0) | 57 (26.9) | |
| Twice per week or more | 22 (17.1) | 21 (9.9) | |
| Smoked cigarette during study periods (18 months) | 0.919 | ||
| No | 4 (3.1) | 7 (3.3) | |
| Yes | 125 (96.9) | 205 (96.7) | |
| Number of cigarettes smoked daily, median (IQR) | 10.5 (6–15) | 12.5 (7–19) | 0.023 |
| Number of cigarettes smoked daily (quartiles) | 0.058 | ||
| 0–5 | 30 (23.3) | 41 (19.3) | |
| 6–10 | 36 (27.9) | 50 (23.6) | |
| 11–15 | 37 (28.7) | 49 (23.1) | |
| 16+ | 26 (20.2) | 72 (34.0) | |
| QFT conversion at 18 mos (IFN-γ ≥ 0.70 IU/mL) | |||
| No | 77 (59.7) | — | |
| Yes | 52 (40.3) | — |
*P values for the difference between included versus excluded participants were generated using the Pearson's χ 2 test for categorical variables and the Wilcoxon rank sum for continuous variables.
IFN-γ: interferon-gamma; QFT: QuantiFERON-TB Gold In-Tube; IQR: interquartile range.