Background. To incorporate the spillover effects experienced by carers providing informal care in health policy decisions, new carer-related preference-based measures have been developed for use in economic evaluation, which include the Adult Social Care Outcomes Toolkit for Carers (ASCOT-Carer), Carer Experience Scale (CES), and Care-Related Quality of Life (CarerQoL). The aim of this study was to investigate the extent to which these 3 instruments measure complementary or overlapping constructs. Methods. Data were derived from an online survey undertaken with carers residing in Australia. An exploratory factor analysis was conducted to ascertain the underlying latent constructs of the 3 measures. Results. Data from 351 informal carers yielded a 5-factor model describing general quality of life outside caring, problems due to caring, fulfilment from caring, social support with caring, and relationship with the care recipient. Most of the ASCOT-Carer and the CarerQol items loaded onto the first and second factors, respectively. The greatest overlap was observed between CarerQol and CES items loading onto the other 3 shared common factors. Limitations. Online data collection resulted in inconsistent responses, which had to be removed to yield logical data. A convenience sampling approach may have compromised the generalizability of study findings. Conclusion. Although some overlap was observed, the 3 carer-related preference-based measures seem to tap into different constructs of carer-related quality of life and caring experiences and cannot be used interchangeably.
Keywords: carer-related quality of life; economic evaluation; informal care; outcome measurement; preference-based measures.