title: Vision and quality of life: development of methods for the VisQoL vision-related utility instrument.
abstract: OBJECTIVE
  To describe the methods and innovations used in constructing the VisQoL, a vision-related utility instrument for the health economic evaluation of eye care and rehabilitation programs.
  
  
  METHODS
  The VisQoL disaggregates vision into six items. Utilities were estimated for item worst responses (the worst level for each item, with all other items at their best level) and VisQoL all-worst responses (all items at their worst level) using the time trade-off procedure. Time trade-off questions require people to imagine living a fixed number of years with a particular health condition and then indicate how many of those years of life they would be willing to trade to have perfect health. Where respondents indicated a health state was "worse than death" negative utilities were estimated. Time trade-off questions minimized the "focusing effect," which occurs if respondents discount the fact that all other aspects of health are at their best when answering questions, by using pictorial and verbal aids.
  
  
  RESULTS
  Item utilities were combined using a multiplicative model, and VisQoL model utilities placed on a scale where 0.00 and 1.00 represent full health and death, respectively. The VisQoL allows utilities to be calculated for a wide range of vision-related conditions.
  
  
  CONCLUSIONS
  The 6-item VisQoL has excellent psychometric properties and is specifically designed to be sensitive to vision-related quality of life. It is the first instrument to permit the rapid estimation of utility values for use in economic evaluations of vision-related programs.
authors.affiliation: Centre for Health Economics in Cancer, British Columbia Cancer Agency, Vancouver, British Columbia, Canada. speacock@bccrc.ca
authors.forename: Stuart
authors.initials: S
authors.lastname: Peacock
authors.forename: Roseanne
authors.initials: R
authors.lastname: Misajon
authors.forename: Angelo
authors.initials: A
authors.lastname: Iezzi
authors.forename: Jeff
authors.initials: J
authors.lastname: Richardson
authors.forename: Graeme
authors.initials: G
authors.lastname: Hawthorne
authors.forename: Jill
authors.initials: J
authors.lastname: Keeffe
mesh_terms: D003362:Cost-Benefit Analysis; D006801:Humans; D008962:Models, Theoretical; D011594:Psychometrics / Q000379:methods; D011788:Quality of Life; D018434:Sickness Impact Profile; D011795:Surveys and Questionnaires; D014786:Vision Disorders / Q000523:psychology*; D014785:Vision, Ocular / Q000502:physiology*; D014792:Visual Acuity / Q000502:physiology; D019987:Persons with Visual Disabilities / Q000523:psychology*
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