title: Values for health states with different life durations.
abstract: BACKGROUND
  Recent research suggests that the value of health states may depend on their duration, implying a more complex relationship between quality and quantity of life than the standard linear relationship assumed in the quality-adjusted life years (QALY) model.
  
  
  OBJECTIVE
  This study models how duration affects the value of health states, using discrete choice data.
  
  
  METHODS
  A study was conducted comprising health profiles including various durations. Health states were described with the EQ-5D. Duration was introduced as a sixth domain with six levels (1, 5, 10, 15, 30, 50 years). Sixty pairs of health profiles were selected, applying a Bayesian approach. Two hundred eight university students self-completed the computerized response tasks. Data were analyzed with a conditional logistic regression model.
  
  
  RESULTS
  There is clear evidence for non-linear values for duration, that is, preferences for duration are more accurately described by a logarithmic function.
  
  
  CONCLUSIONS
  In discrete choice experiments using health states with different durations, these data present the first evidence for decreasing marginal utility for duration. Our results suggest that refinement of the standard QALY framework may be needed for states with a long duration.
authors.affiliation: Department of Clinical Medicine and Prevention, Faculty of Medicine, Research Centre on Public Health, University of Milano-Bicocca, Villa Serena, Via Pergolesi 33, 20052, Monza, Italy. luciana.scalone@unimib.it.
authors.forename: Luciana
authors.initials: L
authors.lastname: Scalone
authors.affiliation: Department for Health Evidence, Radboud University Medical Centre, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands.
authors.forename: Peep F M
authors.initials: PF
authors.lastname: Stalmeier
authors.affiliation: Department of Occupational Medicine, Institute of Medical Statistics and Biometrics "GA Maccacaro", Faculty of Medicine, University of Milano, Cascina Rosa, Via Vanzetti 5, 20133, Milano, Italy.
authors.forename: Silvano
authors.initials: S
authors.lastname: Milani
authors.affiliation: Department of Epidemiology, University Medical Center Groningen, University of Groningen, P.O. Box 30.001, 9700 RB, Groningen, The Netherlands.
authors.forename: Paul F M
authors.initials: PF
authors.lastname: Krabbe
mesh_terms: D000203:Activities of Daily Living; D000293:Adolescent; D000328:Adult; D001499:Bayes Theorem; D005260:Female; D006304:Health Status; D006801:Humans; D008017:Life Expectancy; D016015:Logistic Models; D008297:Male; D057240:Patient Preference / Q000523:psychology*; D011788:Quality of Life; D019057:Quality-Adjusted Life Years; D011795:Surveys and Questionnaires / Q000592:standards*; D013997:Time Factors; D055815:Young Adult
keywords: Discrete choice analysis; Duration; Health states; Quality-adjusted life years; Time preferences; Values