Distribution of background characteristics as stratified by tuberculin skin test and T-Spot.TB status
| Variables | Tuberculin reaction | T-Spot.TB | ||||
| <10 mm | ≥10 mm | p-value | Negative | Positive | p-value | |
| Subjects n | 45 | 88 | 49 | 84 | ||
| Male sex | 98 | 97 | 1.00# | 100 | 95 | 0.30# |
| Smoking status | 0.19¶ | 0.14¶ | ||||
| Never | 21 | 15.2 | 16.7 | 17.4 | ||
| Ex-smoker | 64 | 57 | 69 | 54 | ||
| Current | 14.3 | 28 | 14.6 | 29 | ||
| Alcohol use | 14.3 | 8.7 | 0.33 | 12.5 | 9.3 | 0.56 |
| BCG scar | 2.4 | 1.1 | 0.53# | 2.1 | 1.2 | 1.00# |
| Comorbidity+ | 16.7 | 19.6 | 0.69 | 18.8 | 18.6 | 0.98 |
| Principal job | 0.50¶ | 0.31¶ | ||||
| Underground driller§ | 38 | 47 | 35 | 49 | ||
| Surface drillerƒ | 38 | 37 | 42 | 35 | ||
| Other | 23 | 16.3 | 23 | 16.3 | ||
| Nodule profusion | 0. 76¶ | 0.56¶ | ||||
| Category 1 | 69 | 74 | 73 | 72 | ||
| Category 2 | 29 | 25 | 27 | 26 | ||
| Category 3 | 2.4 | 1.1 | 0.0 | 2.3 | ||
| Nodule size mm | 0.88¶ | 0.52¶ | ||||
| <1.5 | 26 | 26 | 27 | 25 | ||
| 1.5–3 | 67 | 64 | 60 | 67 | ||
| 3–10 | 7.1 | 9.8 | 12.5 | 7.0 | ||
| PMF | 23.8 | 17.4 | 0.38 | 25 | 16.3 | 0.22 |
| Age yrs | 63.6±9.0 | 58.9±9.7 | 0.01 | 61.3±9.8 | 59.9±9.7 | 0.42 |
| Cigarette pack-yr | 24.7±24.6 | 19.9±18.0 | 0.20 | 24.8±20.2 | 19.5±18.8 | 0.28 |
| Body mass index kg·m−2 | 23.8±3.5 | 24. 3±2.8 | 0. 35 | 24.0±3.5 | 24.4±2.7 | 0.45 |
| Dust exposure yr | 23.2±9.7 | 22.8±8.3 | 0.77 | 23.8±7.6 | 22.4±9.3 | 0.39 |
Data are presented as % or mean±sd, unless otherwise stated. BCG: bacilli Calmette–Guérin; PMF: progressive massive fibrosis. #: Fisher exact, two-tailed p-value; ¶: univaviate analysis of each variable by age group; +: diabetes mellitus, heart/cerebrovascular disease, malignancies, cirrhosis and renal and gastrointestinal diseases; hypertension alone was not included; §: caisson workers/tunnel workers/miners; ƒ: surface drillers/stone-splitters/drillers in construction trade or quarries.