Table 1

Classification of severity of airflow obstruction

Postbronchodilator FEV₁/FVC	FEV₁% predicted	NICE 2004	ATS/ERS 2004	GOLD 2008	NICE 2010
Postbronchodilator FEV₁/FVC	FEV₁% predicted	Severity of airflow obstruction
			Postbronchodilator	Postbronchodilator	Postbronchodilator
<0.7	≥80		Mild	Stage 1: Mild	Stage 1: Mild^*
<0.7	50–79	Mild	Moderate	Stage 2: Moderate	Stage 2: Moderate
<0.7	30–49	Moderate	Severe	Stage 3: Severe	Stage 3: Severe
<0.7	<30	Severe	Very severe	Stage 4: Very severe^†	Stage 4: Very severe^†

↵* Symptoms should be present to diagnose chronic obstructive pulmonary disease in people with mild airflow obstruction.
↵† Or FEV₁ <50% with respiratory failure.
ATS, American Thoracic Society; ERS, European Respiratory Society; FEV₁, forced expiratory volume in 1 s; FVC, forced vital capacity; GOLD, Global Initiative for Chronic Obstructive Lung Disease; NICE, National Institute for Health and Clinical Excellence.