Relative health spillover effects of disabled older adults on informal caregivers: evidence using EQ-5D-5L and CarerQol

Preference-weighted evidence on caregiver health spillover effects in China remains limited, particularly in long-term care settings using caregiver-care recipient dyadic data. This study estimated the relative health spillover associations between care-recipient health-related quality of life (HRQoL) and informal caregivers’ HRQoL and care-specific quality-of-life (CRQoL) to inform future economic evaluations and targeted caregiver support. A cross-sectional survey was conducted among informal caregiver-care-recipient dyads in China. Care-recipient HRQoL was assessed using the EQ-5D-5L, while caregivers completed the EQ-5D-5L and CarerQol instrument. Relative spillover effects were estimated using univariable and multivariable linear regression models. Ordered logistic regression examined domain-level associations, and subgroup analyses explored heterogeneity by caregiver gender, care setting, care-recipient cognitive function, and caregiver-recipient relationship. Among 469 dyads, caregivers had a mean age of 66.3 years, and 64.0% were female. Higher care-recipient HRQoL was positively associated with caregiver EQ-5D-5L utility (Coef = 0.171; standardized β = 0.211) and CarerQol utility (Coef = 18.727; standardized β = 0.172) in the primary model (Model 3; both p < 0.001). Better care-recipient financial status was associated with both caregiver outcomes. Caregiver EQ-5D-5L utility was more closely associated with caregivers’ own health and sociodemographic characteristics, whereas CarerQol was linked to caregiving-related factors. Domain-level analyses indicated associations with pain/discomfort, anxiety/depression, financial problems, physical health problems, and caregiving fulfillment. Formal interaction tests showed no clear evidence of subgroup differences. Positive relative spillover associations were found between care-recipient HRQoL and informal caregiver outcomes, supporting their consideration in future economic evaluations and long-term care decision-making. Not applicable.