Table 1.

Spirometry Essentials for Asthma and COPD

	Adult Lung Function Parameters
Condition and Severity	FEV1	FEV1/FVC
Asthma
Intermittent	>80% predicted	Normal*
Mild persistent	>80% predicted	Normal*
Moderate persistent	60%–79% predicted	Reduced ≤5% from normal*
Severe persistent	<60% predicted	Reduced >5% from normal*
COPD†
Mild	≥80% predicted	<0.7
Moderate	50%–79% predicted	<0.7
Severe	30%–49% predicted	<0.7
Very severe	<30% predicted or <50% predicted plus chronic respiratory failure	<0.7

COPD = chronic obstructive pulmonary disease; FEV₁=forced expiratory volume in 1 s; FVC=forced vital capacity

^*Normal FEV₁/FVC = 85% for patients aged 8 to 19 y; 80% for patients aged 20 to 39 y; 75% for patients aged 40 to 59 y; 70% for patients aged 60 to 80 y.

^†Postbronchodilator FEV₁ recommended for diagnosis and assessment.