Table 1 Demographic and selected variables among the CWP cases and controls
From: Polymorphisms in interleukin 17A gene and coal workers’ pneumoconiosis risk in a Chinese population
Variables | CWP (n = 697) | Controls (n = 694) | P | ||
|---|---|---|---|---|---|
Number | Percent | Number | Percent | ||
Age, year (mean ± SD) | 68.0 ± 11.1 | 67.1 ± 8.4 | 0.103 | ||
Exposure years (mean ± SD) | 26.6 ± 9.0 | 27.3 ± 7.8 | 0.105 | ||
Smoking status | |||||
Never | 340 | 48.8 | 360 | 51.9 | 0.250 |
Ever | 357 | 51.2 | 334 | 48.1 | |
Former | 163 | 23.4 | 91 | 13.1 | |
Current | 194 | 27.8 | 243 | 35.0 | |
Pack-years smoked | <0.001 | ||||
0 | 340 | 49.2 | 360 | 52.6 | |
0-20 | 223 | 32.0 | 132 | 19.0 | |
>20 | 134 | 19.2 | 202 | 29.1 | |
Work type | 0.534 | ||||
Tunnel and coal mining | 663 | 95.1 | 652 | 94.0 | |
Transport | 16 | 2.3 | 17 | 2.5 | |
Others | 18 | 2.6 | 25 | 3.6 | |
Stage | |||||
I | 415 | 59.5 | |||
II | 219 | 31.4 | |||
III | 63 | 9.0 | |||