Willingness to pay per quality-adjusted life year in a study of knee osteoarthritis.
BACKGROUND
Determining whether a particular medical intervention is cost-effective requires that a threshold of cost per benefit gained be established. As debate continues over the appropriate threshold, we present measures of willingness to pay (WTP) per quality-adjusted life year (QALY) for own health and 2 hypothetical osteoarthritis scenarios.


METHODS
One hundred ninety-three persons, located through random digit dialing in Harris County, Texas, completed face-to-face interviews collecting demographic information and health preferences using visual analog scale, time tradeoff, standard gamble, and WTP methodologies.


RESULTS
The mean WTP/QALY for all methods was lower (range, $1221-$5690/QALY) than many estimates from revealed preference studies and lower than the oft-cited arbitrary cutoff of $50 000. WTP/QALY was highest when participants were judging their personal health improvements as opposed to hypothetical scenarios. There were some significant differences in WTP/QALY across elicitation methodologies for the same scenario. Demographic characteristics were not associated with WTP/QALY measures.


CONCLUSIONS
The health states and improvements in health evaluated here do not contain a risk of mortality, unlike many situations in which WTP/QALY has been previously evaluated. The lower WTP/QALY values found here may indicate that the presence of a mortality risk reduction substantially increases stated WTP/QALY. Appropriate thresholds for cost-effectiveness may be dependent on the context of a situation, including risk of mortality.
Byrne
Margaret M
MM
Department of Epidemiology and Public Health, University of Miami, Florida 33136, USA. mbyrne2@med.miami.edu
O'malley
Kimberly
K
Suarez-Almazor
Maria E
ME
D000328:Adult; D000368:Aged; D005260:Female; D005382:Financing, Personal; D006801:Humans; D007407:Interviews as Topic; D007719:Knee Joint / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000191:economics / Q000628:therapy*; D019057:Quality-Adjusted Life Years; D013781:Texas