| Variable | COPD(n = 96) | No COPD(n = 373)* | Total group(n = 469) |
| Male sex, n (%) | 66 (68.8) | 205 (55.0) | 271 (57.8) |
| Smokers, n (%) | |||
| Current | 21 (21.9) | 28 (7.5) | 49 (10.5) |
| Former | 40 (41.7) | 182 (48.8) | 222 (47.3) |
| FEV1 bronchodilator reversibility ⩾15%, n (%) | 27 (28.1) | 8 (2.1) | 35 (7.5) |
| Peak flow variability ⩾20%, n (%) | 26 (27.1) | 21 (5.6) | 47 (10.0) |
| Mean (SD) age (years) | 65.4 (6.8) | 62.0 (7.3) | 62.7 (7.3) |
| Mean (SD) post-bronchodilator FEV1 (l) | 2.4 (0.8) | 3.2 (0.8) | 3.0 (0.9) |
| Mean (SD) post-bronchodilator FEV1 (% predicted) | 74.0 (17.9) | 99.1 (14.4) | 94.0 (18.3) |
| Mean (SD) post-bronchodilator FEV1/FVC | 60.2 (8.6) | 78.4 (5.3) | 74.7 (9.5) |
| Mean (SD) Tlco/Va (mmol/min/kPa/l) | 1.21 (0.25) | 1.42 (0.18) | 1.37 (0.21) |
| Mean (SD) cigarette pack years (cigarette smokers only) | 27.2 (21.6) (n = 60) | 14.4 (18.4) (n = 185) | 17.6 (20.0) (n = 245) |
COPD, chronic obstructive pulmonary disease, FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; Tlco, gas transfer factor, adjusted for haemoglobin; Va, alveolar volume.
*The “No COPD” group included five subjects who met the spirometric criteria for COPD but had other respiratory disorders (bronchiectasis n = 4, sarcoidosis n = 1).
Note that the age data presented are the age at time of pulmonary function testing and the smoking data presented are derived from the detailed written questionnaire, not the screening questionnaire.