Characteristics of the general population weighted sample
| Characteristics | All | M | F |
| Patients n | 862 | 533 | 329 |
| Sex | |||
| M | 48.5 | ||
| F | 51.5 | ||
| Age yrs | |||
| 40–49 | 36.1 | 35.3 | 36.8 |
| 50–59 | 32.4 | 33.2 | 31.8 |
| 60–69 | 31.5 | 31.6 | 31.4 |
| Education | |||
| High school or University | 42.5 | 48.8 | 65.3 |
| Primary school or no education | 56.7 | 51.2 | 34.7 |
| Social class (occupations)# | |||
| I–II (professional/intermediate) | 18.1 | 23.2 | 13.1 |
| III (skilled nonmanual) | 32.0 | 30.7 | 33.2 |
| IV–V (manual) | 49.8 | 40.1 | 53.7 |
| Smoking behaviour | |||
| Never smoker | 52.7 | 25.4 | 78.3 |
| Former Smoker | 24.1 | 41.5 | 7.8 |
| Smoker>20 pack-yrs | 13.1 | 24.1 | 2.9 |
| Smoker⩽20 pack-yrs | 10.0 | 9.0 | 10.9 |
| Respiratory diseases | |||
| COPD | 10.2 | 16.0 | 4.8 |
| Asthma | 3.6 | 3.8 | 3.4 |
| Spirometric results | |||
| FVC mL | 3454.5±877.7 | 4024.7±795.5 | 2916.9±552.2 |
| FEV1 mL | 2578.6±726.4 | 2959.5±762.8 | 2219.5±459.7 |
| % FVC over pred | 90.3±13.8 | 87.0±13.8 | 93.5±13.1 |
| % FEV1 over pred | 89.5±16.5 | 84.9±17.8 | 93.7±13.8 |
| FEV1/FVC % | 99.2±11.1 | 96.6±12.0 | 101.6±9.4 |
Data are presented as % or mean±sd unless otherwise stated
M: male
F: female
COPD: chronic obstructive pulmonary disease
FVC: forced vital capacity
FEV1: forced expiratory volume in one second
#: social class based on an adaptation of the British General's Classification 26