Characteristics of control and chronic obstructive pulmonary disease(COPD) study subjects
| Control | COPD | p-value | |
| Subjects n | 912 | 1017 | |
| Male % | 63.6 | 69.8 | 0.0038 |
| Age yrs | 60.8±8.9 | 65.9±8.2 | <0.0001 |
| Smoking pack-yrs | 38.7±17.4 | 48.7±22.8 | <0.0001 |
| FEV1 % pred | 95.4±11.0 | 43.2±15.2 | <0.0001 |
| FEV1/FVC | 77.8±4.9 | 47.6±12.1 | <0.0001 |
Data are presented as mean±sd, unless otherwise stated. FEV1: forced expiratory volume in one second; % pred: % predicted; FVC: forced vital capacity.