Exploring relative health spillover effects within the context of dementia using the EQ-HWB-9

Dementia does not only impact the quality of life of the affected individual but also their family and informal caregivers, often referred to as health spillover effects. Increasing attention is being given to the inclusion of informal caregiver spillover effects in economic evaluations, given their potential to directly influence funding recommendations.

The objective of this study was to estimate the relative health spillover effects of dementia caregiving on informal caregivers using the EQ Health and Wellbeing 9-items (EQ-HWB-9) questionnaire.

A cross-sectional survey was conducted involving informal caregivers of people with dementia residing in Australia. Informal caregivers completed the experimental version of EQ-HWB to rate their own health and wellbeing and proxy reported for the person with dementia using the EQ-HWB-9. To estimate the relative spillover, univariate and multiple linear regressions modeled caregiver's EQ-HWB-9 scores (derived from the EQ-HWB) as a function of the person with dementia health and wellbeing (based on the EQ-HWB-9), adjusting for demographic and caregiving characteristics.

In total, 202 informal caregivers completed the survey. The average age of caregivers was 60.4 (SD = 13.7), with 63.2% being female. The univariate analysis revealed a positive relative spillover effect coefficient of 0.23 (p < 0.001, R-squared = 0.10), demonstrating a significant positive association between caregiver's and person's with dementia health and wellbeing using the EQ-HWB-9. This relationship remained significant (p < 0.001, adj R-squared = 0.26) when adjusting for caregiver's chronic conditions in the multiple linear regression model yielding a spillover coefficient of 0.22. Most impacted domains of caregiving included exhaustion, loneliness and lack of control over day-to-day life.

There is evidence of associative relative health spillovers associated with providing informal care for a person with dementia. It is essential to include health effects on informal caregivers into economic evaluations to account for the burden of dementia posed beyond the affected individual.