Chronic obstructive pulmonary disease by severity according to Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria.
| Stage | FEV1/FVC | FEV1 predicted (%) |
|---|---|---|
| Mild (GOLD I) | <0.7 | ≥80 |
| Moderate (GOLD II) | <0.7 | 50–80 |
| Severe (GOLD III) | <0.7 | 30–50 |
| Very severe (GOLD IV) | <0.7 | <30 |
FEV1/FVC = forced expiratory volume in 1 second/forced vital capacity ratio.