Measuring health and broader wellbeing benefits in the context of opiate dependence: the psychometric performance of ICECAP-A and EQ-5D-5L: Using ICECAP-A and EQ-5D-5L in drug addiction

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Background: Measuring outcomes in economic evaluations of social care interventions is challenging, as both health and wellbeing benefits are evident. The ICEpop CAPability instrument for Adults (ICECAP-A) and the five-level EuroQol-5D (EQ-5D-5L) are measures potentially suitable for the economic evaluation of treatments for substance use disorders. However, evidence for their validity in this context is lacking. Objective: To assess the construct validity of the ICECAP-A and EQ-5D-5L, in terms of convergent and discriminative validity, and sensitivity to change based on standard clinical measures (CORE-OM, TOP, ISEL, LDQ, and SSQ). Methods: Secondary analysis of pilot trial data for heroin users in opiate substitution treatment. Baseline convergence with clinical measures was assessed using Pearson's correlation coefficient. Discriminative validity was assessed using one-way ANOVA and stepwise regressions. Sensitivity to changes in clinical indicators were assessed at 3 and 12 months using the standardised response mean statistic, and parametric and non-parametric testing. Results: Both measures had the same level of construct validity, except for clinical indicators of wellbeing, where the ICECAP-A performed better. The ICECAP-A was sensitive to changes in both health and wellbeing 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 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 where recovery is the desired outcome.


Original languageEnglish
Pages (from-to)820-828
Number of pages9
JournalValue in Health
Issue number6
Early online date9 Jun 2016
Publication statusPublished - 26 Mar 2019


  • addiction , construct validity , economic evaluation , EQ-5D , ICECAP , mental health , outcome valuation , sensitivity to change