Patient characteristics and lung function
| Controls | COPD | p-value | |
| Patients | 405 | 154 | |
| Female/male | 239/166 (59/41) | 71/83 (46/54) | 0.006 |
| Age, years | 62±8 | 66±6 | <0.001 |
| Weight, kg | 77±16 | 77±15 | 0.99 |
| Height, cm | 170±9 | 171±9 | 0.025 |
| Smoking status, never-/former/current smoker | 76/145/184 | 5/92/57 | <0.001 |
| Smoking, pack-years | 22±18 | 36±20 | <0.001 |
| GOLD stage 1/2/3/4 | NA | 23/96/31/4 | NA |
| Lung function | |||
| FEV1, L | 2.85±0.71 | 1.87±0.64 | <0.001 |
| FEV1, % pred | 97±13 | 63±17 | <0.001 |
| FVC, L | 3.40±0.85 | 3.19±1.02 | 0.023 |
| FVC, % pred | 91±12 | 83±19 | <0.001 |
| FEV1/FVC | 0.84±0.06 | 0.60±0.17 | <0.001 |
| RV, % pred | 116±21 | 150±45 | <0.001 |
| TLC, % pred | 102±11 | 106±17 | 0.003 |
| DLCO, % pred | 93±16 | 66±20 | <0.001 |
| VA, % pred | 96±16 | 91±13 | <0.001 |
| DLCO/VA, % pred | 97±15 | 72±20 | <0.001 |
| R5, kPa·s·L−1 | 0.31±0.11 | 0.41±0.17 | <0.001 |
| R20, kPa·s·L−1 | 0.24±0.08 | 0.28±0.09 | <0.001 |
| R5–R20, kPa·s·L−1 | 0.07±0.05 | 0.13±0.10 | <0.001 |
| X5, kPa·s·L−1 | −0.09±0.05 | −0.18±0.13 | <0.001 |
| AX, kPa·s·L−1 | 0.34±0.39 | 1.13±1.33 | <0.001 |
Data are presented as n, n (%) or mean±sd, unless otherwise stated. Significant differences are depicted in bold. Categorical data were analysed using the Chi-squared test and numeric data were analysed with the t-test. GOLD: Global Initiative for Chronic Obstructive Lung Disease; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; RV: residual volume; TLC: total lung capacity; DLCO: diffusing lung capacity of the lung for carbon monoxide; VA: alveolar volume; R5: resistance at 5 Hz; R20: resistance at 20 Hz; X5: reactance at 5 Hz; AX: reactance area; NA: not applicable.