Characteristics of participants
| Parameters | n=10 187 |
| Age (years) | 59.6 (9.0) |
| Sex, female (%) | 4741 (46.5) |
| Race, African American (%) | 3407 (33.4) |
| Body mass index (kg/m2) | 28.8 (6.3) |
| Smoking pack-years | 44.2 (25.0) |
| Smoking duration (years) | 36.4 (10.0) |
| Cigarettes/day | 24.3 (11.3) |
| Current smokers (%) | 5414 (53.2) |
| FEV1 (L) | 2.24 (0.92) |
| FEV1 % predicted | 76.4 (25.6) |
| FVC (L) | 3.30 (1.01) |
| FVC % predicted | 87.0 (18.3) |
| FEV1/FVC | 0.67 (0.16) |
| CT emphysema (%) | 6.2 (9.6) |
| CT gas trapping (%) | 21.9 (19.9) |
| 6 min walk distance (m) | 411.5 (121.6) |
| St George’s Respiratory Questionnaire score (units) | 27.4 (22.9) |
All values are expressed as mean (SD) unless otherwise indicated.