Baseline characteristics of the subjects
| Smoking controls | COPD | p Value | |
| No of subjects | 143 | 320 | |
| Age (years) | 61 (58–65) | 65 (60–720) | <0.001 |
| Body mass index | 27 (24–29) | 25 (22–28) | <0.001 |
| Sex | |||
| Men (%) | 109 (76) | 252 (79) | 0.55 |
| Women (%) | 34 (24) | 68 (21) | |
| Smoking history | |||
| Pack-years | 39 (30–53) | 46 (33–61) | 0.002 |
| Smoking status | |||
| Current smokers (%) | 81 (57) | 179 (56) | |
| FEV1 (litres) | 3.1 (2.6–3.6) | 1.4 (0.96–2.23) | <0.001 |
| FEV1 (% predicted) | 102 (94–111) | 53 (36–76) | <0.001 |
| FVC (litres) | 4.2 (3.4–4.8) | 3.2 (2.4–3.9) | <0.001 |
| FEV1/FVC | 0.75 (0.73–0.79) | 0.48 (0.37–0.62) | <0.001 |
| GOLD stages | 1–4 | ||
| GOLD 1 (%) | 72 (23) | ||
| GOLD 2 (%) | 97 (30) | ||
| GOLD 3 (%) | 92 (29) | ||
| GOLD 4 (%) | 59 (18) | ||
| Emphysema | |||
| CT evidence (%) | 8 (6) | 224 (70) | <0.001 |
| No CT evidence (%) | 134 (94) | 96 (30) | |
| CT unavailable (%) | 1 (0) | 0 (0) | |
| Median elastin antibodies (relative units) | 52 (34–67) | 40 (27–61) | 0.001 |
Parameters are expressed as median with IQR. Sex, smoking status, GOLD stages and the presence of emphysema are expressed as percentages. Mann–Whitney or Fisher exact p values are reported.
COPD, chronic obstructive pulmonary disease; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; GOLD, Global Initiative for Chronic Obstructive Lung Disease.