Development and validation of the recovering quality of life (ReQoL) outcome measures

This report presents the development and initial validation of the 10-item and 20-item self-reported, recovery-focused quality of life outcome measures named Recovering Quality of Life (ReQoL). The development of the ReQoL was commissioned by the Department of Health as an instrument to measure outcomes of mental health service users aged 16 and over in primary, secondary and tertiary care settings. The ReQoL measures are recovery focussed as they adequately capture all the key themes associated with recovery.

Methods

We adopted a mixed methods approach in a four-stage process. We employed qualitative methods for theme identification, item development (stage I) and initial testing with over 76 service users aged 16 and over (stage II). We adopted quantitative methods for establishing dimensionality through exploratory and confirmatory factor analyses, item reduction and scale construction using Item Response Theory and classical psychometrics with data obtained from >6500 service users (stage III). A selection of items for 10 and 20-item versions synthesised psychometric evidence from item response theory models and classical psychometrics, as well as qualitative evidence (stage IV). Reliability was examined by Cronbach’s alpha, test re-test reliability coefficients, validity via convergence, known group differences using standardised effect sizes, and responsiveness using standardised response means.

Results

ReQoL-10 and ReQoL-20 contain positively and negatively worded items which reflect one physical health item and the following six mental health quality of life themes: activity, hope, belonging and relationships, self-perception, wellbeing, and autonomy. Unidimensionality was established showing that the items measure one construct of mental health quality of life and recovery. Both versions of

the ReQoL achieved acceptable internal consistency (alpha >.92) and test-retest reliability (>.85). They reflected known group differences (general population versus patient population and the severity of non-psychotic conditions), convergence with related measures, and were responsive over time (SRM>.4). ReQoL-10 and ReQoL-20 performed marginally better than SWEMWBS and markedly better than EQ-5D.

Conclusions

The ReQoL measures offer a number of important advantages over existing measures. They are the only ones known to the authors that have been built around the themes of recovery. The measures have been co-produced with service users who have been involved in all stages of the project as participants, advisers, partners and decision-makers. By virtue of the high face and content validity which is a result of co-production with service users as well as its brevity and good psychometric properties, ReQoL-10 has the potential to be a useful outcome measure for use in routine clinical practice. ReQoL-20 can also be used in routine practice mainly at assessment and end of treatment but also in research studies.

The measures are now available for use and licences can be obtained from the University of Oxford Innovation Ltd.