Recommendations for Diagnosis and Management of Osteoporosis in COPD Men

Table 3

Spirometric classification of chronic obstructive pulmonary disease severity based on postbronchodilator FEV₁ [4, 11].

Stage I: mild	FEV1/FVC < 0.70 FEV1⩾ 80% predicted
Stage II: moderate	FEV1/FVC < 0.70 50% ⩽ FEV1 < 80% predicted
Stage III: severe	FEV1/FVC < 0.70 30% ⩽ FEV1 <50% predicted
Stage IV: very severe	FEV1/FVC < 0.70 FEV1 < 30% predicted or FEV1 < 50% predicted plus chronic respiratory failure*

FEV₁: forced expiratory volume in 1 second; FVC: forced vital capacity
*Respiratory failure: arterial partial pressure of oxygen (Pao₂) <8.0 kPa (60 mm Hg) with or without arterial partial pressure of CO₂(Paco₂) >6.7 kPa (50 mm Hg) while breathing air at sea level.