| Stage |
Symptoms |
Pulmonary functions |
| 0 – Imminent |
Chronic, sputum producing cough |
Normal |
| I – Mild |
With or without chronic symptoms |
Mildly limited ventilationFEV1/FVC ˂ 70%FEV1 ≥ 80% |
| II – Moderate |
Advanced symptomatology, dyspnoea resulting from physical load |
Worse ventilationFEV1/FVC ˂ 70%50% ≥ FEV1 ˂ 80% |
| III – Severe |
Escalated dyspnoea and repeated exacerbations, strongly limiting the patient's quality of life |
Severe ventilation defectFEV1/FVC ˂ 70%30% ≥ FEV1˂ 50% |
| IV – Extremely severe |
Severe chronic respiratory problems; the quality of life is even more limited; life threatening exacerbations |
Most severe ventilation defectsFEV1/FVC < 70% FEV1 < 30% |
