Developing an Australian Value Set for the COCOON Carer Quality-of-Life Measure for Use in Economic Evaluations

Informal carers play a crucial role in supporting people with dementia, yet their experiences are often overlooked in policy and funding decisions because of limited suitable outcome measures. The COCOON measure advances the assessment of carers' quality of life for economic evaluations but lacks a value set. This study aimed to develop a value set to support the measure's use in economic evaluations.

A discrete choice experiment with duration was conducted with a representative sample of Australian adults. The discrete choice experiment included seven COCOON dimensions (emotional health, physical health, loss and grief, loss of freedom, loneliness, support and financial burden) and a duration attribute. Using a partial profile design with three fixed and five varying attributes, 240 choice tasks were created and divided into 24 blocks, with each respondent completing ten tasks. An unadjusted conditional logit model was estimated followed by an adjusted model that corrected illogical ordering, from which anchored coefficients were derived by mapping utilities onto a conventional 0-1 utility scale.

A total of 771 respondents were included. An adjusted conditional logit model correcting illogical orderings provided the final value set. The resulting value set showed that financial burden had the greatest influence on utility, followed by physical health, loneliness and support. Values ranged from 1 for the best possible state to - 0.7014 for the worst state.

This study provides the first Australian COCOON value set, enabling the derivation of preference-weighted utility values and facilitating the inclusion of carer outcomes in economic evaluations of dementia care.