Characteristics | Non-COPD (n = 519) | COPD (n = 119) | P Value | ||
---|---|---|---|---|---|
 | N | % | N | % |  |
Pneumoconiosis category | |||||
 I | 323 | 62.24 | 29 | 24.37 | 0.00 a,** |
 II | 114 | 21.97 | 18 | 15.13 | |
 III | 82 | 15.80 | 72 | 60.50 | |
Exposure type | |||||
 Silicosis | 113 | 21.77 | 29 | 24.37 | 0.54 a |
 Coal | 406 | 78.23 | 90 | 75.63 | |
Engaged in Air drill | |||||
 Yes | 264 | 50.87 | 74 | 62.18 | 0.03 a,* |
 No | 255 | 49.13 | 45 | 37.82 | |
 Age,y | 49.00(46.00,53.00) | 53.00(48.00,60.00) | 0.00 b,** | ||
 BMI, kg/m2 | 23.14(21.30,25.22) | 22.32(20.10,24.37) | 0.01 b,** | ||
 Exposure time, y | 15.00 (10.00,25.00) | 20.00(13.00,25.00) | 0.01 b,* | ||
 Smoking index | 12.50(0.00,27.00) | 20.00(1.25,32.00) | 0.02 b,* | ||
 Education | 2.00(1.00,2.00) | 2.00(1.00,2.00) | 0.25 | ||
 Category | 1.00(1.00,2.00) | 3.00(2.00,3.00) | 0.00 b,** | ||
Pulmonary function | |||||
 Airflow limitation | 0.00(0.00,0.00) | 2.00(2.00,3.00) | 0.00 b,** | ||
 Pre-FEV1 | 89.70(81.40,98.60) | 57.90(41.60,70.60) | 0.00 b,** | ||
 Pre-FVC | 91.30(83.30,99.40) | 76.80(65.40,87.20) | 0.00 b,** | ||
 FEV1/FVC | 80.56(75.94,84.55) | 62.19(51.84,65.63) | 0.00 b,** | ||
 DLCO | 8.29(7.13,9.44) | 6.86(5.42,7.99) | 0.00 b,** | ||
 DLCO% | 91.90(79.20,104.50) | 76.40(60.60,88.50) | 0.00 b,** | ||
Severity scores | |||||
 Cough | 1.00(1.00,3.00) | 2.00(1.00,3.00) | 0.37 | ||
 Sputum | 1.00(1.00,3.00) | 2.00(1.00,3.00) | 0.39 | ||
 Wheeze | 0.00(0.00,0.00) | 0.00(0.00,1.00) | 0.00 b,** | ||
 Dyspnea | 2.00(2.00,2.00) | 2.00(2.00,2.00) | 0.00 b,** | ||
 Chest tightness | 2.00(1.00,3.00) | 2.00(1.00,3.00) | 0.29 | ||
 CAT | 10.00(7.00,14.00) | 13.00(8.00,17.00) | 0.00 b,** | ||
 CCQ | 21.00(16.00,26.00) | 25.00(21.00,29.00) | 0.00 b,** |