Table 1: Disease Staging and General Symptomsa

Stage FEV1/FVC FEV1 Predicted General COPD Symptoms
I (mild) <0.7 ≥80% Chronic cough or sputum production may be present (but not always)
II (moderate) <0.7 50% ≥FEV1 <80% Exertional dyspnea develops (cough and sputum production sometimes present); some patients may have frequent exacerbations
III (severe) <0.7 30% ≥FEV1 <50% Greater exertional dyspnea, fatigue and repeated exacerbations
IV (very severe) <0.7 FEV1 <30% or 50% predicted plus chronic respiratory failure Symptoms worsen; potentially life-threatening exacerbations

FEV1=forced expiratory volume in 1 second; FVC=forced vital capacity; COPD=chronic obstructive pulmonary disease.
a Please refer to reference [5] as cited in text.