Table 4.

Willingness to pay estimates for chronic obstructive pulmonary disease attributes by disease severity (N = 506)

Attributes and levels	Marginal WTP to avoid level by COPD disease severitya (95 % CI)
	Mild (N = 108)	Moderate (N = 238)	Severe/very severe (N = 160)
Relieves symptoms (reference: complete relief)
Little or no relief	$61.97 (51.21–72.74)	$65.54 (57.52–73.56)	$67.51 (56.31–78.71)
Some relief	$30.51 (19.74–41.27)	$29.36 (21.34–37.38)	$26.64 (15.44–37.83)
Feel medicine start to work (reference: within 5 min)
Within 20 min	$5.48 (0.92–10.04)	$10.42 (7.17–13.68)	$13.41 (8.72–18.10)
Within 30 min or more	$10.43 (5.87–15.00)	$10.04 (6.79–13.29)	$18.33 (13.64–23.02)
Ease of use (reference: quick and easy)
Requires some practice and care	$8.70 (3.55–13.86)	$6.08 (2.52–9.63)	−$0.19 (−$5.40–5.02)
More difficult and time-consuming	$11.88 (6.72–17.04)	$19.20 (15.65–22.76)	$12.81 (7.60–18.01)
Rescue medicine use (reference: rarely, 1–2 times per week or less)
3–5 times per week	$20.50 (11.15–29.86)	$19.98 (12.88–27.07)	$18.13 (8.10–28.16)
Every day	$36.02 (26.67–45.38)	$33.68 (26.58–40.78)	$24.54 (14.51–34.56)
Side effects (reference: no side effects)
Mild side effects	$19.41 (14.45–24.38)	$13.46 (9.97–16.95)	$13.46 (8.57–18.35)
Moderate to severe side effects	$61.03 (56.07–66.00)	$57.77 (54.28–61.26)	$60.35 (55.46–65.24)

Reference was the most favorable level for each COPD medication attribute. 95 % CIs that did not include zero were considered to be statistically significant. Negative marginal WTP value for ‘Ease of use’ was due to a relatively small difference in preference between attribute levels ‘Quick and easy’ and ‘Requires some practice and care’

CI confidence interval, COPD chronic obstructive pulmonary disease, WTP willingness to pay

^aCOPD disease severity was participant-reported (Mild, Moderate, Severe, Very severe, Don’t know). Nine participants with response ‘Don’t know’ were excluded