Table 3. Association analysis for QFT positivity among smokers.
| Variables | N† | % | p for χ2 test | Adjusted OR#(95% CI) |
|---|---|---|---|---|
| Gender | ||||
| Female | 41/131 | 31.30 | 0.528 | Reference |
| Male | 1427/4961 | 28.76 | 0.91 (0.62.1.35) | |
| Age (years) | ||||
| 5–19 | 4/46 | 8.70 | <0.001 | Reference |
| 20–29 | 58/506 | 11.46 | 1.30 (0.45,3.75) | |
| 30–39 | 108/590 | 18.31 | 1.72 (0.58,5.09) | |
| 40–49 | 331/1285 | 25.76 | 2.27 (0.76,6.72) | |
| 50–59 | 367/1139 | 32.22 | 2.74 (0.91,8.19) | |
| 60–69 | 394/1033 | 38.14 | 3.25 (1.08,9.79) | |
| ≥70 | 206/493 | 41.78 | 3.53 (1.15, 10.85) | |
| Education level | ||||
| Primary school or lower | 731/2179 | 33.55 | <0.001 | |
| Middle school | 560/2162 | 25.90 | ||
| High school | 155/643 | 24.11 | ||
| College or higher | 22/108 | 20.37 | ||
| Household per capita income (RMB) | ||||
| <6000 | 924/3108 | 29.74 | 0.076 | |
| ≥6000 | 544/1984 | 27.42 | ||
| BMI (kg/m2) | ||||
| 18.5–24.0 | 814/2766 | 29.43 | 0.520 | |
| <18.5 | 71/276 | 25.72 | ||
| 24.0–28.0 | 436/1515 | 28.78 | ||
| ≥28.0 | 147/535 | 27.48 | ||
| Alcohol drinking | ||||
| No | 732/2358 | 31.04 | 0.001 | |
| Yes | 736/2734 | 26.92 | ||
| TB contact history | ||||
| No | 1381/4862 | 28.40 | 0.002 | Reference |
| Yes | 87/228 | 38.16 | 1.48 (1.12,1.97) | |
| History of T2DM | ||||
| No | 1352/4751 | 28.46 | 0.029 | |
| Yes | 116/341 | 34.02 | ||
| Smoking status | ||||
| Former smoker | 101/352 | 28.69 | 0.953 | |
| Current smoker | 1367/4740 | 28.84 | ||
| Cigarette type | ||||
| Without filter | 108/324 | 33.33 | 0.064 | |
| With filter | 1360/4768 | 28.52 | ||
| Onset of cigarette smoking (years) | ||||
| <18 | 279/927 | 30.10 | 0.346 | |
| ≥18 | 1189/4165 | 28.55 | ||
| Duration of smoking (years) | ||||
| ≤10 | 96/753 | 12.75 | <0.001 | Reference |
| 10–20 | 199/891 | 22.33 | p for trend<0.001 | 1.45 (1.02, 2.06) |
| 20–30 | 366/1305 | 28.05 | 1.65 (1.14, 2.40) | |
| 30–40 | 392/1138 | 34.45 | 1.90(1.28, 2.82) | |
| 40–50 | 294/726 | 40.50 | 2.09 (1.36, 3.19) | |
| >50 | 121/279 | 43.37 | 2.26 (1.38, 3.69) | |
| Number of cigarettes per day | ||||
| 1–5 | 126/507 | 24.85 | 0.009 | |
| 5–10 | 182/683 | 26.65 | p for trend<0.001 | |
| 10–19 | 525/1912 | 27.46 | ||
| ≥20 | 635/1990 | 31.91 |
Abbreviations: BMI = body mass index; CI = confidence interval; OR = odds ratio; QFT = QuantiFERON-TB Gold In-Tube; T2DM = type 2 diabetes mellitus; TB = tuberculosis.
† Indeterminate results had been excluded from the analysis. Sum might not always be in total because of missing data.
# Adjusted for variables with p < 0.05 in univariate analysis by stepwise selection. Sex and age kept in the model.