Estimating an exchange-rate between care-related and health-related quality of life outcomes for economic evaluation: An application of the wellbeing valuation method.

ABSTRACT

Quality of life outcomes for family carers and patients may be measured in different ways within the same economic evaluation. We used the wellbeing valuation method to calculate "exchange rates" between care-related outcomes (the Carer Experience Scale and CarerQoL-7D) and health-related (the EQ-5D-5L) outcomes. Data on quality of life outcomes were collected through a postal quality of life survey in the UK. A random effects model was used to estimate carers' wellbeing as a function of their EQ-5D-5L, Carer Experience Scale (or CarerQoL-7D) and a set of control variables. When life satisfaction was used as the measure of wellbeing, a one-point gain in the Carer Experience Scale (0-100 scale) was equivalent (in wellbeing terms) to a 0.014 gain in EQ-5D-5L value; and a one point gain in the CarerQoL-7D (0-100 scale) was equivalent to a 0.033 gain in EQ-5D-5L. The exchange rate values were reduced when capability was used as the measure of wellbeing. The exchange rates estimated in this study offer a means to place carer and patient outcomes, measured via different quality of life instruments, on a common scale, although there are important issues to consider in operationalising the technique.