Chronic obstructive pulmonary disease severity classification
| GOLD stage | FEV1 % predicted | Patients n | |
| Mild | 1 | ≥80% | 2 |
| Moderate | 2 | ≥50% and <80% | 16 |
| Severe | 3 | ≥30% and <50% | 9 |
| Very severe | 4 | <30% | 3 |
| Total | 30 |
GOLD: Global Initiative for Chronic Obstructive Lung Disease; FEV1: forced expiratory volume in 1 s.