title: Valuing Health Using Time Trade-Off and Discrete Choice Experiment Methods: Does Dimension Order Impact on Health State Values?
abstract: BACKGROUND
  Health states defined by multiattribute instruments such as the EuroQol five-dimensional questionnaire with five response levels (EQ-5D-5L) can be valued using time trade-off (TTO) or discrete choice experiment (DCE) methods. A key feature of the tasks is the order in which the health state dimensions are presented. Respondents may use various heuristics to complete the tasks, and therefore the order of the dimensions may impact on the importance assigned to particular states.
  
  
  OBJECTIVE
  To assess the impact of different EQ-5D-5L dimension orders on health state values.
  
  
  METHODS
  Preferences for EQ-5D-5L health states were elicited from a broadly representative sample of members of the UK general public. Respondents valued EQ-5D-5L health states using TTO and DCE methods across one of three dimension orderings via face-to-face computer-assisted personal interviews. Differences in mean values and the size of the health dimension coefficients across the arms were compared using difference testing and regression analyses.
  
  
  RESULTS
  Descriptive analysis suggested some differences between the mean TTO health state values across the different dimension orderings, but these were not systematic. Regression analysis suggested that the magnitude of the dimension coefficients differs across the different dimension orderings (for both TTO and DCE), but there was no clear pattern.
  
  
  CONCLUSIONS
  There is some evidence that the order in which the dimensions are presented impacts on the coefficients, which may impact on the health state values provided. The order of dimensions is a key consideration in the design of health state valuation studies.
authors.affiliation: University of Technology Sydney, Centre for Health Economics Research and Evaluation, Ultimo, NSW 2007, Australia; Health Economics and Decision Science, School of Health and Related Research, University of Sheffield, Sheffield UK. Electronic address: Brendan.mulhern@chere.uts.edu.au.
authors.forename: Brendan
authors.initials: B
authors.lastname: Mulhern
authors.affiliation: Office of Health Economics, London, UK.
authors.forename: Koonal
authors.initials: K
authors.lastname: Shah
authors.affiliation: Department of Medical Psychology and Psychotherapy, Erasmus MC, Erasmus University, Amsterdam, The Netherlands.
authors.forename: Mathieu F Bas
authors.initials: MF
authors.lastname: Janssen
authors.affiliation: Health Economics Research Group, Brunel University London, Uxbridge, Middlesex, UK.
authors.forename: Louise
authors.initials: L
authors.lastname: Longworth
authors.affiliation: Centre for Health and Social Care, Sheffield Hallam University, Sheffield, UK.
authors.forename: Rachel
authors.initials: R
authors.lastname: Ibbotson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016009:Chi-Square Distribution; D002755:Choice Behavior; D004739:England; D005260:Female; D006304:Health Status; D006305:Health Status Indicators; D006306:Health Surveys; D006801:Humans; D007407:Interviews as Topic; D016013:Likelihood Functions; D016014:Linear Models; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011788:Quality of Life; D011897:Random Allocation; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D013997:Time Factors; D026712:Value of Life; D055815:Young Adult
keywords: EQ-5D; discrete choice; health state valuation; health-related quality of life; time trade-off