Table 4.

Subgroup analysis quantifying heterogeneity in patient preferences

Attribute	Level	Subgroup	Marginal utility	95% CI	WTP	p Value
Route	Take oral tablet over subcutaneous injection	Sex (female)	0.07	0.02 to 0.11	$201.24	<0.01
		Sex (male)	−0.07	−0.11 to −0.02	$66.79
		Race (white)	0.09	0.03 to 0.14	$182.23	<0.01
		Race (black)	−0.09	−0.14 to −0.03	$18.48
		Injury (lower extremity)	0.08	0.02 to 0.15	$132.38	0.01
		Injury (upper extremity)	−0.08	−0.15 to −0.02	$18.98
Bleeding complications requiring transfusion	Reduce risk by 1%	Injury (lower extremity)	−0.02	−0.03 to −0.003	$14.50	0.01
		Injury (upper extremity)	0.02	0.003 to 0.03	$32.04
Wound complications requiring another surgery	Reduce risk by 1%	Recruitment (inpatient)	0.02	0.003 to 0.03	$46.32	<0.01
		Recruitment (outpatient)	−0.02	−0.03 to −0.003	$20.24

Marginal utility quantifies the additional satisfaction gained by the patient for each described attribute/level. Negative marginal utility values signify an aversion to or dissatisfaction with the described attribute/level. All willingness to pay values are presented in reference to a less preferred option. For example, both females and males prefer oral tablets compared with a subcutaneous injection. However, females are willing to pay more for an oral tablet over a subcutaneous injection than males are willing to pay for that same trade-off (oral tablet over subcutaneous injection). Willingness to pay values for attributes with continuous levels estimate the willingness to pay for an additional 1% absolute reduction in risk.

WTP, willingness to pay.