A Biomarker of Stress and Self-reported Caregiving Distress Predict Poor Quality of Life in Family Caregivers of Patients With Heart Failure

Background Family caregivers are at a high risk for low quality of life due to caregiving-related stress. Caregivers' stress is commonly assessed using self-reported measures, which reflect relatively subjective and long-term stress related to caregiving, but objective biological markers of stress are rarely used for caregivers. The purposes of this study were (1) to determine whether caregiver characteristics were associated with stress assessed using a stress biomarker (serum cortisol) and a self-reported caregiving distress measure (Caregiver Burden Inventory) and (2) to determine the predictability of both stress measures for quality of life in caregivers of patients with heart failure. Methods Taiwanese family caregivers (N = 113; mean age, 54.5 years; 70.8% female) of patients with heart failure completed surveys including caregiving distress and quality of life measured by the Caregiver Burden Inventory and the Short Form-36 (physical and psychological well-being subscales), respectively, and provided blood samples for serum cortisol. Independent t tests, correlation, and hierarchical regression were conducted. Results Single caregivers had higher serum cortisol levels than married caregivers (P =.002). Men had significantly higher serum cortisol levels than women (P =.010), but men reported lower caregiving distress than women (P =.049). Both serum cortisol (β = -0.32, P =.012) and caregiving distress (β = -0.29, P =.018) were significant predictors of quality of life in the physical well-being scale while controlling for caregivers' characteristics and depressive symptoms. Serum cortisol (β = -0.28, P =.026) and caregiving distress (β = -0.25, P =.027) also predicted quality of life in the psychological well-being scale. Conclusions Serum cortisol and self-reported caregiving distress have similar predictability for quality of life in family caregivers of patients with heart failure. Reducing stress and caregiving distress is critical to improving quality of life in this population.