Stroke survivors’ long-term QALY-weights in relation to their spouses’ QALY-weights and informal support: a cross-sectional study

BACKGROUND Healthcare interventions that have positive effects on the stroke survivors' health-related quality of life (HRQoL) and quality-adjusted life-years (QALYs) might also have positive effects for their spouses in terms of improved HRQoL and/or reduced spousal informal support. However, knowledge about stroke survivors' HRQoL and QALY and the consequences for their spouses' HRQoL and QALY is limited. Therefore, the aim of this study was to describe the HRQoL and QALY-weights in dyads of stroke survivors in comparison with dyads of healthy controls, and to study the relationship between the stroke survivors' QALY-weights and consequences for spouses in terms of QALY-weight and annual cost of informal support, using a long-term perspective. METHODS Data on stroke survivors, controls, and spouses were collected from the seven-year follow-up of the Sahlgrenska Academy Study on Ischemic Stroke (SAHLSIS). HRQoL was assessed by the SF-36, and the preference-based health state values were assessed with the SF-6D. The magnitude of the support was assessed with a study specific time-diary. An ordinary least squares (OLS) regression was used to estimate the association between stroke survivors' and spouses' QALY-weights. A two-part econometric model was used to estimate the association between stroke survivors' QALY-weights and the time spent and cost of spouses' informal support. RESULTS Cohabitant dyads of 248 stroke survivors' aged <70 at stroke onset and 245 controls were included in the study. Stroke survivors had lower HRQoL in the SF-36 domains physical functioning, physical role, general health, vitality (P < 0.001), and social functioning (P = 0.005) in comparison with their cohabitant spouses. There was no significant difference in HRQoL for the dyads of controls. The results from the regression analyses showed that lower QALY-weights of the stroke survivors were associated with lower QALY-weights of their spouses and increased annual cost of spousal informal support. CONCLUSION Our results show that the QALY-weights for stroke survivors had consequences for their spouses in terms of annual cost of spousal informal support and QALY-weights. Hence, economic evaluation of interventions that improve the HRQoL of the stroke survivors but ignore the consequences for their spouses may underestimate the value of the intervention.