Comparison of capability and health-related quality of life instruments in capturing aspects of mental well-being in people with schizophrenia and depression

Timea Mariann Helter; Joanna Coast; Agata Łaszewska; Tanja Stamm; Judit Simon

doi:10.1192/bjo.2022.514

Comparison of capability and health-related quality of life instruments in capturing aspects of mental well-being in people with schizophrenia and depression

BJPsych Open. 2022 Jun 27;8(4):e117. doi: 10.1192/bjo.2022.514.

Authors

Timea Mariann Helter¹, Joanna Coast², Agata Łaszewska¹, Tanja Stamm³, Judit Simon⁴

Affiliations

¹ Department of Health Economics, Center for Public Health, Medical University of Vienna, Austria.
² Health Economics Bristol, Population Health Sciences, Bristol Medical School, University of Bristol, UK.
³ Section for Outcomes Research, Center for Medical Statistics, Informatics, and Intelligent Systems, Medical University of Vienna, Austria; and Ludwig Boltzmann Institute for Arthritis and Rehabilitation, Vienna, Austria.
⁴ Department of Health Economics, Center for Public Health, Medical University of Vienna, Austria; and Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, UK.

Abstract

Background: There is increasing evidence that assessing outcomes in terms of capability provides information beyond that of health-related quality of life (HRQoL) for outcome evaluation in mental health research and clinical practice.

Aims: To assess similarities and differences in the measurement properties of the ICECAP-A capability measure and Oxford Capabilities Questionnaire for Mental Health (OxCAP-MH) in people with schizophrenia experiencing depression, and compare these measurement properties with those of (a) the EuroQol EQ-5D-5L and EuroQol Visual Analogue Scale (EQ-VAS) and (b) mental health-specific (disease-specific) measures.

Method: Using data for 100 patients from the UK, measurement properties were compared using correlation analyses, Bland-Altman plots and exploratory factor analysis. Responsiveness was assessed by defining groups who worsened, improved or remained unchanged, based on whether there was a clinically meaningful change in the instrument scores between baseline and 9-month follow-up assessments.

Results: The two capability instruments had stronger convergent validity with each other (Spearman's rho = 0.677) than with the HRQoL (rho = 0.354-0.431) or the mental health-specific (rho = 0.481-0.718) instruments. The OxCAP-MH tended to have stronger correlations with mental health-specific instruments than the ICECAP-A, whereas the ICECAP-A had slightly stronger correlation with the EQ-VAS. Change scores on the capability instruments correlated weakly with change scores on the HRQoL scales (rho = 0.131-0.269), but moderately with those on mental health-specific instruments for the ICECAP-A (rho = 0.355-0.451) and moderately/strongly on the OxCAP-MH (rho = 0.437-0.557).

Conclusions: Assessing outcomes in terms of capabilities for people with schizophrenia and depression provided more relevant, mental health-specific information than the EQ-5D-5L or the EQ-VAS. The ICECAP-A and the OxCAP-MH demonstrated similar psychometric properties, but the OxCAP-MH was more correlated with disease-specific instruments.

Keywords: Capability approach; EQ-5D-5L; ICECAP-A; OxCAP-MH; schizophrenia.

Abstract

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