Demographic characteristics of the patients with COPD and healthy volunteers
| Patients with COPD | Controls | p Value | |
| Number of subjects | 25 | 25 | |
| Gender (female), % | 16 | 16 | |
| Age (years), mean±SD (range) | 69.2±8.1 (58–84) | 67.96±8.0 (57–86) | 0.59 |
| Education (years), mean±SD | 6.7±3.9 | 7.5±5.0 | 0.53 |
| Family history of COPD, % | 4 | – | |
| Disease duration (years) | 7.0±5.7 | – | |
| Actual smokers, % | 44 | 40 | 0.86 |
COPD, chronic obstructive pulmonary disease.