| Characteristic | Subjects |
| Males/females | 175 (72.9)/60 (25) |
| Data not available | 5(2.1) |
| Age range yrs | |
| <30 | 7 (2.9) |
| 30–39 | 4 (1.7) |
| 40–49 | 17 (7.1) |
| 50–59 | 55 (22.9) |
| 60–69 | 71 (29.6) |
| >70 | 71 (29.6) |
| Not available | 15 (6.3) |
| BMI kg·m−2 | |
| <18.5 | 7 (2.9) |
| 18.5–24.9 | 77 (32.1) |
| 25.0–29.9 | 66 (27.5) |
| >30 | 25 (10.4) |
| Not available | 65 (25.5) |
| Never-smokers | 38 (15.8) |
| Former smokers | 99 (41.3) |
| Current smokers | 85 (35.4) |
| Tobacco consumption unknown | 18 (7.5) |
| Tobacco consumption pack-yrs | 59.1±64.4 |
| Patients with COPD | 74 (30.8) |
| GOLD stage 1 | 9 (12.2) |
| GOLD stage 2 | 31 (41.9) |
| GOLD stage 3 | 11 (14.9) |
| GOLD stage 4 | 0 (0.0) |
| Not classified | 23 (31.0) |
| Cystic fibrosis | 1 (0.4) |
| Asthma | 5 (2.1) |
| Diffuse interstitial lung disease | 4 (1.7) |
| Bronchiectasis | 4 (1.7) |
| α1-antitrypsin deficiency | 1 (0.4) |
| Sleep apnoea | 12 (5.0) |
| No known respiratory comorbidities | 110 (45.8) |
| Surgery for lung cancer yes/no | 185 (77.1)/21 (8.8) |
| Data not available | 34 (14.2) |
Data are presented as n (%) or mean±sd, unless otherwise stated. n = 240. BMI: body mass index; COPD: chronic obstructive pulmonary disease; GOLD: Global Initiative for Chronic Obstructive Lung Disease.