Mild COPD: Individual may not be aware that his/her lung function is abnormal.
Mild airflow limitation (FEV1/FVC < 70%; FEV1 ≥ 80% predicted) and sometimes, but not always chronic cough and sputum production.
Stage 2: Moderate COPD:
Patients typically seek medical attention at this stage because of chronic respiratory symptoms or an exacerbation of their disease.
Worsening airflow limitation (FEV1/FVC < 70%; FEV1 50% to 80% predicted), with shortness of breath typically developing on exertion.
Stage 3: Severe COPD:
Further worsening of airflow limitation (FEV1/FVC < 70%; FEV1 30% to 50% predicted), greater shortness of breath, reduced exercise capacity, and repeated exacerbations which have an impact on a patient’ quality of life.
Stage 4: Very severe COPD:
At this stage, quality of life is very appreciably impaired and exacerbations may be life-threatening
Severe airflow limitation (FEV1/FVC < 70%; FEV1< 30% predicted or FEV1 < 50% predicted plus chronic respiratory failure).