Table 1.
Demographic details and spirometric results
| Total subjects | Age | Male | Cumulative smoking | Prior diagnosis of asthma | Prior diagnosis of COPD | FEV1 | FEV1/FVC | |
| Number | Years | Number (%) | Pack-years | Number (%) | Number (%) | % predicted | % | |
| All subjects | 1566 | 53.0±8.7 | 985 (62.9%) | 14.1±18.6 | 46 (2.9%) | 10 (0.6%) | 99.6±13.1 | 80.1±5.8 |
| Healthy non-smoking subjects*† | 646 | 53.3±8.8 | 189 (29.3%) | 0.0±0.1 | 17 (2.6%) | 2 (0.3%) | 105.5±10.7 | 82.3±4.4 |
| COPD defined by fixed ratio | 85 | 60.4±9.4 | 83 (97.6%) | 36.9±28.1 | 5 (5.9%) | 4 (4.7%) | 80.2±11.6 | 66.0±4.1 |
| Non-COPD smokers | 817 | 51.9±8.0 | 704 (86.2%) | 23.1±16.9 | 23 (2.8%) | 4 (0.5%) | 97.9±11.8 | 80.1±4.7 |
| Non-COPD never smokers | 664 | 53.4±8.9 | 198 (29.8%) | 0.0±0.0 | 18 (2.7%) | 2 (0.3%) | 104.2±12.0 | 82.0±4.5 |
| COPD defined by LLN | 34 | 57.7±10.4 | 29 (85.3%) | 31.9±25.8 | 2 (5.9%) | 2 (5.9%) | 77.3±13.1 | 63.0±4.9 |
| Non-COPD smokers | 867 | 52.4±8.3 | 755 (87.1%) | 24.2±18.3 | 26 (3.0%) | 6 (0.7%) | 97.1±12.3 | 79.4±5.3 |
| Non-COPD never smokers | 665 | 53.5±8.9 | 201 (30.2%) | 0.0±0.0 | 18 (2.7%) | 2 (0.3%) | 104.1±12.1 | 82.0±4.5 |
*FEV1 of >85% predicted and FEV1/FVC of >0.7.
†A smoking history of <1 pack-year.
COPD, chronic obstructive pulmonary disease; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; LLN, lower limit of normal.