Willingness to pay per quality-adjusted life year in a study of knee osteoarthritis

Margaret M. Byrne, Kimberly O'Malley, Maria E. Suarez-Almazor

Research output: Contribution to journalArticlepeer-review

55 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)655-666
Number of pages12
JournalMedical Decision Making
Issue number6
StatePublished - Nov 2005


  • Cost-effectiveness
  • Quality-adjusted life year
  • Willingness-to-pay

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health
  • Health Informatics
  • Health Information Management
  • Nursing(all)


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