Clinical features

Why?

Clinical impression of moderate or severe COPD makes it 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)	clinical impression: moderate-severe	4.2 (2.2 to 8.0)	29%
		clinical impression: mild	0.82 (0.55 to 1.2)	8%
		clinical impression: no disease	0.42 (0.25 to 0.70)	4%

A clinical prediction rule may be better, looking for the following 4 features: ^b

• self-report history of COPD
• aged > 45
• smoking > 40 pack-years
• maximum laryngeal height < 4 cm 

Patient	Target Disorder and Reference Standard	Diagnostic Test	LR+ (95% CI)	Post-test Probability	LR- (95% CI)	Post-test Probability
patient visting doctor b (pre-test probability: 52%)	COPD (spirometry)	all 4 factors present	220	100%	0.13	12%