Lung functional characteristics of nonobstructed and obstructed subjects
| Nonobstructed | Obstructed | |
| FEV1 % pred | 103±15 | 64±17 |
| FVC % pred | 106±12 | 83±17 |
| FEV1/FVC | 0.77±0.4 | 0.60±0.8 |
| FEF25% % pred | 81±23 | 32±18 |
| FEF50% % pred | 100±41 | 29±11 |
| FEF75% % pred | 84±36 | 41±18 |
| FEF25–75% % pred | 61±5 | 27±10 |
Data are presented as mean±sd. FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; FEFx%: forced expiratory flow at 25%, 50% and 75% of FVC. p<0.0001 for all comparisons.