title: Preparatory study for the revaluation of the EQ-5D tariff: methodology report.
abstract: BACKGROUND
  EQ-5D is a widely used generic measure of health with a 'tariff', or preference weights, obtained from the general population, using time trade-off (TTO). PRET (Preparatory study for the Re-valuation of the EQ-5D Tariff project) contributes towards the methodology for its revaluation.
  
  
  METHODS
  Stage 1 examined key assumptions typically involved in health-state valuations through a series of binary choice exercises, namely that health-state preferences are independent of (1) duration of the state; (2) whose health it is (i.e. perspective); (3) length of 'lead time' (a mechanism to value all states on the same scale, including those who are worse than being dead); (4) when health events take place (time preference); and (5) satisfaction associated with the state. Further topics addressed were (6) exhaustion of lead time in the worst state; (7) health-state valuation using discrete choice experiments (DCEs) with a duration attribute; and (8) binary choice administration of lead time - time trade-off (LT-TTO). Stage 1 consisted of an online survey with 6000 respondents. Stage 2 compared the results above to those of an identical survey conducted in 200 face-to-face computer-assisted personal interviews (CAPIs), covering topics (1) to (7). Stages 3 and 4 examined - in more detail and depth - issues taken from stage 1. Stage 3 consisted of CAPI surveys of a representative UK sample of 300, using examples of TTO, LT-TTO, and DCE with duration, each followed by extensive feedback questions. Stage 4 was a more intensive exercise involving a qualitative analysis of people's thought processes during both binary choice and iterative health-state valuation exercises. Data were collected through 'think-aloud' methods in 30 interviews of a convenience sample.
  
  
  RESULTS
  Stage 1 found that health-state values are not independent of (1) duration of the state but there is no clear pattern; (2) whose health it is; (3) the duration of 'lead time' but there was no clear pattern; (4) when health events take place; or (5) satisfaction associated with the state. Furthermore, (6) exhaustion of lead time in the worst state was subject to substantial framing effects; (7) the five-level version of the EQ-5D (EQ-5D-5L) can be valued using DCE with duration as an attribute; and (8) binary choice LT-TTO can be administered in an online environment. Stage 2 found that although online surveys and CAPI surveys resulted in different compositions of respondents, at the aggregate, their responses to the experimental questions covering (1) to (7) above were not statistically significantly different from each other. Stages 3 and 4 found that TTO and LT-TTO were easier than DCE with duration; respondents did not necessarily trade across all attributes of EQ-5D; some respondents found it difficult to distinguish between the two worst levels of EQ-5D-5L, and some respondents may be thinking about the impact of their ill health on their family.
  
  
  CONCLUSIONS
  In order for the National Institute for Health and Care Excellence to make the most appropriate decisions, the EQ-5D tariff needs to incorporate the latest understanding of health-state preferences. PRET contributed to the knowledge base on the conduct of health-state valuation studies.
  
  
  BACKGROUND
  The Medical Research Council (MRC)-National Institute for Health Research (NIHR) Methodology Research Programme funded the PRET project (MRC ref. G0901500), and the EuroQol Group funded the PRET-AS project (Preparatory study for the Re-valuation of the EQ-5D Tariff project - Additional Sample) as an extension to the PRET project with formal agreement from the MRC.
authors.affiliation: Health Economics and Decision Science, School of Health and Related Research, University of Sheffield, Sheffield, UK.
authors.forename: Brendan
authors.initials: B
authors.lastname: Mulhern
authors.affiliation: School of Population and Public Health, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Nick
authors.initials: N
authors.lastname: Bansback
authors.affiliation: Health Economics and Decision Science, School of Health and Related Research, University of Sheffield, Sheffield, UK.
authors.forename: John
authors.initials: J
authors.lastname: Brazier
authors.affiliation: Health Economist (freelance), Aberdeen, UK.
authors.forename: Ken
authors.initials: K
authors.lastname: Buckingham
authors.affiliation: Department of Health Services Research and Policy, London School of Hygiene and Tropical Medicine, London, UK.
authors.forename: John
authors.initials: J
authors.lastname: Cairns
authors.affiliation: Office of Health Economics, London, UK.
authors.forename: Nancy
authors.initials: N
authors.lastname: Devlin
authors.affiliation: London School of Economics, London, UK.
authors.forename: Paul
authors.initials: P
authors.lastname: Dolan
authors.affiliation: Department of Economics, University of Sheffield, Sheffield, UK.
authors.forename: Arne Risa
authors.initials: AR
authors.lastname: Hole
authors.affiliation: London School of Economics, London, UK.
authors.forename: Georgios
authors.initials: G
authors.lastname: Kavetsos
authors.affiliation: Health Economics Research Group, Brunel University, London, UK.
authors.forename: Louise
authors.initials: L
authors.lastname: Longworth
authors.affiliation: Health Economics and Decision Science, School of Health and Related Research, University of Sheffield, Sheffield, UK.
authors.forename: Donna
authors.initials: D
authors.lastname: Rowen
authors.affiliation: Health Economics and Decision Science, School of Health and Related Research, University of Sheffield, Sheffield, UK and Department of Economics, University of Sheffield, Sheffield, UK.
authors.forename: Aki
authors.initials: A
authors.lastname: Tsuchiya
mesh_terms: D000293:Adolescent; D000328:Adult; D026683:Advisory Committees; D000368:Aged; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D057240:Patient Preference / Q000523:psychology*; D011788:Quality of Life; D019057:Quality-Adjusted Life Years; D011795:Surveys and Questionnaires; D006113:United Kingdom; D055815:Young Adult