Assessing measurement properties of EQ-5D-5L and ICECAP-A in patients with chronic depression in England.

BACKGROUND: EQ-5D and ICECAP-A instruments are widely used as outcome measures in economic evaluation. This study aimed to evaluate the validity and responsiveness of EQ-5D-5L and ICECAP-A for economic evaluation in patients with chronic depression in England. METHODOLOGY: Data from 365 patients with chronic depression who took part in a cluster randomised controlled trial were used. The EQ-5D-5L, ICECAP-A and four additional outcome measures (MANSA, BDI-II, MADRS and CGI-S) were administrated at baseline and 12-months post-randomisation. We assessed the floor/ceiling effect, structural validity, convergent validity, known-group validity, and responsiveness of EQ-5D-5L and ICECAP-A in this population. RESULTS: Exploratory factor analysis with pooled EQ-5D-5L and ICECAP-A items suggested a two-factor solution (i.e. psychosocial wellbeing and physical functioning factors). The EQ-5D-5L index and ICECAP-A index were positively correlated with each other (ρ = 0.578, p < 0.001). The two measures correlated the strongest with the BDI-II, and the weakest with CGI-S. Both EQ-5D-5L index and ICECAP-A index showed good discriminative ability. Mental health condition specific measures (BDI-II, MADRS and CGI-S) and a subjective quality of life measure (MANSA) reported better responsiveness than EQ-5D-5L index and ICECAP-A index. The ICECAP-A index reported better responsiveness than the EQ-5D-5L index. The responsiveness of the EQ-5D-5L was largely driven by the anxiety/depression dimension, followed by the usual activities dimension. For the ICECAP-A, four attributes of the instrument reported good responsiveness except for the autonomy attribute. CONCLUSIONS: EQ-5D-5L and ICECAP-A showed good validity and responsiveness among patients with chronic depression in England. We recommend ICECAP-A as an outcome measure in economic evaluation for medical interventions that aim to improve the psychosocial wellbeing of adults with chronic depression for the instrument’s structural validity and its better responsiveness than the EQ-5D-5L. TRIAL REGISTRATION: The trial was registered on 13/06/2019. The registration number is ISRCTN11301686.