Table 1 Demographic characteristics of the subjects
|  | Non-smokers(NC) n = 25 | Smokers (NS) n = 25 | Non-smokers with COPD (CN) n = 10 | Smokers with COPD (CS) n = 18 |
|---|---|---|---|---|
Sex (female/male) | 20/5 | 1/24 | 9/1 | 0/18 |
Age (years) | 55 ± 9 | 56 ± 11 | 59 ± 7 | 61 ± 9 |
Smoking history, pack-years | ― | 26 ± 14 | ― | 37 ± 25 |
FEV1,% predicted | 97 ± 15 | 99 ± 11 | 65 ± 17 | 70 ± 16 |
FEV1/FVC% | 84 ± 8 | 80 ± 7 | 56 ± 7 | 61 ± 5 |
GOLD stage | Â | Â | Â | Â |
1 | ― | ― | 1 | 1 |
2 | ― | ― | 7 | 12 |
3 | ― | ― | 2 | 5 |
4 | ― | ― | ― | ― |