title: Measuring Health and Broader Well-Being Benefits in the Context of Opiate Dependence: The Psychometric Performance of the ICECAP-A and the EQ-5D-5L.
abstract: BACKGROUND
  Measuring outcomes in economic evaluations of social care interventions is challenging because both health and well-being benefits are evident. The ICEpop CAPability instrument for adults (ICECAP-A) and the five-level EuroQol five-dimensional questionnaire (EQ-5D-5L) are measures potentially suitable for the economic evaluation of treatments for substance use disorders. Evidence for their validity in this context is, however, lacking.
  
  
  OBJECTIVE
  To assess the construct validity of the ICECAP-A and the EQ-5D-5L in terms of convergent and discriminative validity and sensitivity to change on the basis of standard clinical measures (Clinical Outcomes in Routine Evaluation-Outcome Measure, Treatment Outcomes Profile, Interpersonal Support Evaluation List, Leeds Dependence Questionnaire, and Social Satisfaction Questionnaire).
  
  
  METHODS
  A secondary analysis of pilot trial data for heroin users in opiate substitution treatment was conducted. Baseline convergence with clinical measures was assessed using the Pearson correlation coefficient. Discriminative validity was assessed using one-way analysis of variance and stepwise regressions. Sensitivity to changes in clinical indicators was assessed at 3 and 12 months using the standardized response mean statistic and parametric and nonparametric testing.
  
  
  RESULTS
  Both measures had the same level of construct validity, except for clinical indicators of well-being, for which the ICECAP-A performed better. The ICECAP-A was sensitive to changes in both health and well-being indicators. The EQ-5D-5L had lower levels of sensitivity to change, and a ceiling effect (27%), particularly evident in the dimensions of self-care (89%), mobility (75%), and usual activities (72%).
  
  
  CONCLUSIONS
  The findings support the construct validity of both measures, but the ICECAP-A gives more attention to broader impacts and is more sensitive to change. The ICECAP-A shows promise in evaluating treatments for substance use disorders for which recovery is the desired outcome.
authors.affiliation: Health Economics Unit, Institute of Applied Health Research, University of Birmingham, Birmingham, UK.
authors.forename: Ilias
authors.initials: I
authors.lastname: Goranitis
authors.affiliation: School of Social and Community Medicine, University of Bristol, Bristol, UK.
authors.forename: Joanna
authors.initials: J
authors.lastname: Coast
authors.affiliation: Research and Innovation Department, Birmingham and Solihull Mental Health NHS Foundation Trust, Birmingham, UK; Addictions Department, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK.
authors.forename: Ed
authors.initials: E
authors.lastname: Day
authors.affiliation: Research and Innovation Department, Birmingham and Solihull Mental Health NHS Foundation Trust, Birmingham, UK; School of Psychology, University of Birmingham, Birmingham, UK.
authors.forename: Alex
authors.initials: A
authors.lastname: Copello
authors.affiliation: Department of Primary Care and Population Health, University College London, London, UK.
authors.forename: Nick
authors.initials: N
authors.lastname: Freemantle
authors.affiliation: Research and Innovation Department, Birmingham and Solihull Mental Health NHS Foundation Trust, Birmingham, UK.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Seddon
authors.affiliation: Research and Innovation Department, Birmingham and Solihull Mental Health NHS Foundation Trust, Birmingham, UK.
authors.forename: Carmel
authors.initials: C
authors.lastname: Bennett
authors.affiliation: Health Economics Unit, Institute of Applied Health Research, University of Birmingham, Birmingham, UK. Electronic address: E.Frew@bham.ac.uk.
authors.forename: Emma
authors.initials: E
authors.lastname: Frew
mesh_terms: D000328:Adult; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D009293:Opioid-Related Disorders / Q000628:therapy*; D010549:Personal Satisfaction; D010865:Pilot Projects; D011594:Psychometrics; D011788:Quality of Life; D015203:Reproducibility of Results; D012944:Social Support; D011795:Surveys and Questionnaires / Q000592:standards*
keywords: EQ-5D; ICECAP; addiction; construct validity; economic evaluation; mental health, outcome valuation; sensitivity to change