Randomized trial of presenting absolute v. relative risk reduction in the elicitation of patient values for heart disease prevention with conjoint analysis.
BACKGROUND
The authors performed a randomized controlled trial to test the effect of 2 different formats of risk reduction information when using conjoint analysis to elicit values about heart disease prevention.


METHODS
Participants ages 30 to 75 were enrolled and presented the same hypothetical scenario: a person with a 13% ten-year risk of heart disease. Participants then worked through a values elicitation exercise using conjoint analysis, making pairwise comparisons of hypothetical treatments that differed on 5 attributes. For the attribute "ability to reduce heart attacks," participants were randomized to receive either absolute risk reduction (ARR) or relative risk reduction (RRR) information. Participants selected which attribute they felt was most important. Participants' responses to the pairwise comparisons were then used to generate their most important attribute using ordinary least squares regression. Outcomes included differences between groups in the proportion choosing and generating ability to reduce heart attacks as the most important attribute.


RESULTS
In total, 113 participants completed the study: mean age was 51, 29% were male, 52% were white, and 42% were African American. The proportion who selected the ability to reduce heart attacks as the most important treatment attribute did not differ significantly (64% RRR; 53% ARR, Fisher's P=0.26). For the conjoint-generated most important attribute, those receiving the RRR version were significantly more likely to generate ability to reduce heart attacks as the most important attribute (59% RRR; 35% ARR, Fisher's P=0.01).


DISCUSSION
Risk presentation format appears to affect the perceived value of different treatment attributes generated from conjoint analysis.