Background/clinical characteristics of silicotic patients at tuberculin testing
| Variable | Tuberculin reaction | Overall | p-value | |
| <10 mm | ≥10 mm | |||
| Subjects n | 118 | 317 | 435 | |
| Age yrs | 58.4±9.9 | 57.3±9.9 | 57.6±9.9 | 0.315 |
| Smoking status | 0.011 | |||
| Never-smoker | 16.1 | 9.1 | 11.0 | |
| Ex-smoker | 44.9 | 36.9 | 39.1 | |
| Current smoker | 39.0 | 53.9 | 49.9 | |
| Current cigarette·day−1 | 3.9±8.3 | 4.6±6.8 | 4.4±7.3 | 0.360 |
| Cigarette pack-yrs | 24.0±20.1 | 22.7±21.5 | 23.1±21.1 | 0.543 |
| Regular alcohol use | 5.1 | 13.6 | 11.3 | 0.013 |
| BCG scar | 1.7 | 3.8 | 3.2 | 0.369# |
| BMI | 23.1±3.4 | 23.8±3.3 | 23.6±3.3 | 0.079 |
| With other comorbidities¶ | 40.7 | 40.1 | 40.2 | 0.907 |
| Principal job | 0.104 | |||
| Underground driller+ | 36.4 | 46.4 | 43.7 | |
| Surface driller§ | 31.4 | 32.2 | 32.0 | |
| Fine silicaƒ | 5.1 | 3.2 | 3.7 | |
| Other jobs## | 27.1 | 18.3 | 20.7 | |
| Exposure to dust yrs | 24.2±9.4 | 24.2±8.3 | 24.2±8.6 | 0.957 |
| Profusion of nodules | 0.066 | |||
| Category 1 | 66.9 | 65.9 | 66.2 | |
| Category 2 | 27.1 | 32.2 | 30.8 | |
| Category 3 | 5.9 | 1.9 | 3.0 | |
| Size of nodules mm | 0.700 | |||
| <1.5 | 28.0 | 32.2 | 31.0 | |
| 1.5–3 | 61.0 | 57.4 | 58.4 | |
| 3–10 | 11.0 | 10.4 | 10.6 | |
| Regular shape of nodules | 81.4 | 82.3 | 82.1 | 0.878 |
| Progressive massive fibrosis | 18.6 | 17.7 | 17.9 | 0.813 |
Data are presented as % or mean±sd, unless otherwise stated. BCG: bacille Calmette–Guérin; BMI: body mass index. #: Fisher exact, two-tailed p-value; ¶: hypertension, diabetes mellitus and other heart, cerebrovascular, lung, gastrointestinal and renal diseases; +: caisson workers/tunnel workers/miners; §: surface drillers/stone-splitters/drillers in the construction trade or quarries; ƒ: involving fine silica powder in gem-, ceramic- or glass-related work; ##: with medium or low silica dust exposure.