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.

CharacteristicIncludedNot included value*
(%) (%)

Gender0.806
 Male107 (82.9)178 (84.0)
 Female22 (17.1)34 (16.0)
Age, median (IQR)38 (32–43)37 (30–42)0.247
Education0.389
 Up to primary39 (30.2)76 (35.8)
 Primary to middle60 (46.5)83 (39.2)
 High school and higher30 (23.3)53 (25.0)
Unstable housing0.357
 No113 (87.6)178 (84.0)
 Yes16 (12.4)34 (16.0)
History of incarceration0.719
 No78 (60.5)124 (58.5)
 Yes51 (39.5)88 (41.5)
HIV infection0.366
 No123 (95.3)197 (92.9)
 Yes6 (4.7)15 (7.1)
Alcohol0.154
 None76 (58.9)134 (63.2)
 Less than twice per week31 (24.0)57 (26.9)
 Twice per week or more22 (17.1)21 (9.9)
Smoked cigarette during study periods (18 months)0.919
 No4 (3.1)7 (3.3)
 Yes125 (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
 0–530 (23.3)41 (19.3)
 6–1036 (27.9)50 (23.6)
 11–1537 (28.7)49 (23.1)
 16+26 (20.2)72 (34.0)
QFT conversion at 18 mos (IFN-γ ≥ 0.70 IU/mL)
 No77 (59.7)
 Yes52 (40.3)

values for the difference between included versus excluded participants were generated using the Pearson’s 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.