title: Validation of the underlying assumptions of the quality-adjusted life-years outcome: results from the ECHOUTCOME European project.
abstract: BACKGROUND
  Quality-adjusted life-years (QALYs) have been used since the 1980s as a standard health outcome measure for conducting cost-utility analyses, which are often inadequately labeled as 'cost-effectiveness analyses'. This synthetic outcome, which combines the quantity of life lived with its quality expressed as a preference score, is currently recommended as reference case by some health technology assessment (HTA) agencies. While critics of the QALY approach have expressed concerns about equity and ethical issues, surprisingly, very few have tested the basic methodological assumptions supporting the QALY equation so as to establish its scientific validity.
  
  
  OBJECTIVE
  The main objective of the ECHOUTCOME European project was to test the validity of the underlying assumptions of the QALY outcome and its relevance in health decision making.
  
  
  METHODS
  An experiment has been conducted with 1,361 subjects from Belgium, France, Italy, and the UK. The subjects were asked to express their preferences regarding various hypothetical health states derived from combining different health states with time durations in order to compare observed utility values of the couples (health state, time) and calculated utility values using the QALY formula.
  
  
  RESULTS
  Observed and calculated utility values of the couples (health state, time) were significantly different, confirming that preferences expressed by the respondents were not consistent with the QALY theoretical assumptions.
  
  
  CONCLUSIONS
  This European study contributes to establishing that the QALY multiplicative model is an invalid measure. This explains why costs/QALY estimates may vary greatly, leading to inconsistent recommendations relevant to providing access to innovative medicines and health technologies. HTA agencies should consider other more robust methodological approaches to guide reimbursement decisions.
authors.affiliation: Data Mining International, Route de l'Aéroport, 29-31, CP 221, 1215, Geneva 15, Switzerland, aberesniak@datamining-international.com.
authors.forename: Ariel
authors.initials: A
authors.lastname: Beresniak
authors.forename: Antonieta
authors.initials: A
authors.lastname: Medina-Lara
authors.forename: Jean Paul
authors.initials: JP
authors.lastname: Auray
authors.forename: Alain
authors.initials: A
authors.lastname: De Wever
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Praet
authors.forename: Rosanna
authors.initials: R
authors.lastname: Tarricone
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Torbica
authors.forename: Danielle
authors.initials: D
authors.lastname: Dupont
authors.forename: Michel
authors.initials: M
authors.lastname: Lamure
authors.forename: Gerard
authors.initials: G
authors.lastname: Duru
mesh_terms: D003362:Cost-Benefit Analysis; D003657:Decision Making; D005060:Europe; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D015233:Models, Statistical; D017063:Outcome Assessment, Health Care / Q000379:methods; D057240:Patient Preference; D019057:Quality-Adjusted Life Years; D012051:Reimbursement Mechanisms; D013673:Technology Assessment, Biomedical / Q000379:methods*; D013997:Time Factors