Clinical features

Note:

• Measure expiratory time, by timing expiratory sounds that are audible over the sternum during forced expiration. 

A prolonged expiratory time makes COPD more likely

Patient	Target Disorder and Reference Standard	Diagnostic Test	LR+ (95% CI)	Post-test Probability
suspected COPD a (pre-test probability: 9%)	COPD (spirometry)	forced expiratory time > 9 sec	4.8	32%
		6-9 sec	2.7	21%
		<6 sec	0.45	4%