Using a Discrete Choice Experiment to Elicit Time Trade-Off and Willingness-to-Pay Amounts for Influenza Health-Related Quality of Life at Different Ages
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Recent research suggests that values for health-related quality of life may vary with the age of the patient. Traditional health state valuation questions and discrete choice experiments are two approaches that could be used to value health.
To measure whether public values for health vary with the age of the affected individual.
A discrete choice experiment was administered via the Internet in December 2007 to measure preferences for different attributes of influenza-related health-related quality of life: age of hypothetical affected individual (range 1–85 years), length of episode (days of illness), severity of illness (workdays lost) and time trade-off or willingness-to-pay amounts. Each respondent answered identical choice questions for a hypothetical family member and for himself/herself. Data on sociodemographic characteristics and influenza illness experience were also collected. Respondents were US adults randomly sampled from an Internet survey panel (n = 1,012). The relative value of attributes was estimated using generalized estimating equations and controlling for sociodemographic characteristics and illness experience. Marginal time traded and marginal willingness to pay using discrete choice and traditional time trade-off or willingness-to-pay questions were compared.
Respondents preferred shorter influenza episodes but did not significantly prefer fewer workdays lost if episode length was held constant. Respondents were more likely to choose to avert uncomplicated illness in children and less likely to choose to avert uncomplicated illness in working-age adults. Marginal time trade-off and willingness-to-pay amounts elicited using discrete choice questions were larger than those elicited using direct valuation questions.
Approaches that assume values for health-related quality of life do not vary with the age of a patient may bias economic analyses that use these values. If patient age could affect valuations, then age should be included in the valuation exercise. Additional research should evaluate the effect of patient age on values for other conditions.
KeywordsInfluenza Discrete Choice Choice Task Discrete Choice Experiment Influenza Illness
The authors would like to acknowledge Drs. Timothy Uyeki and Laurie Kamimoto (Centers for Disease Control and Prevention [CDC]) for assistance in developing descriptions of influenza illness and Dr. David Pihlens (Centre for the Study of Choice, University of Technology Sydney) for consultation on the experimental design. The authors would also like to thank Dr. Tracy Lieu and Dr. Steve Roberts for providing constructive comments, as well as Acham Gebremariam and Kara Lamarand for analytic and research assistance.
Dr. Prosser conceived and designed the study, led the analysis, and wrote the paper. She can also serve as guarantor for the overall content. Dr. Payne contributed to the design and analysis of the study as well as contributing to drafting the paper. Ms. Rusinak assisted with survey development, led survey administration, and contributed to revising the paper. Ms. Shi contributed to the analytic plan and conducted the statistical analyses. Dr. Messonnier contributed to the design of the study and interpretation of results, and contributed to drafting the paper.
Funding for this project was provided from the Harvard-CDC Joint Initiative in Vaccine Economics. Dr. Payne was also funded in part by an RCUK academic fellowship. The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the CDC.
Conflicts of interest
The authors do not have any known conflicts of interest to declare.
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