Table 4: Natural History Model Input Parameters by COPD Severity^*.

Model Parameter	Mild	Moderate	Severe	Very Severe
Annual total exacerbation rate (95% CI) (14)	0.82	1.17	1.61	2.1
	(0.46−1.49)	(0.93−1.50)	(1.51−1.74)	(1.51−2.94)
Annual major exacerbation rate (95% CI) (14)	0.11	0.16	0.22	0.28
	(0.02−1.49)	(0.07−0.33)	(0.20−0.23)	(0.14−0.63)
No exacerbation–utility value (12;15)	0.85	0.81	0.76	0.66
Annual maintenance cost (16)	$500	$500	$1,488	$2,176

^*Abbreviations: CI, confidence interval; COPD, chronic obstructive pulmonary disease.