Magnitude and causes of bias among family caregivers rating Alzheimer disease patients.

OBJECTIVE: Family caregivers generally underestimate the health and well-being of Alzheimer disease (AD) patients when compared to patients' self-assessments. The goals of this study were to identify caregiver, patient, and contextual factors associated with caregiver rating bias.
METHODS: One hundred five patients with AD, along with their family caregivers, were assessed twice by trained interviewers 1-year apart. In separate interviews, caregivers were asked to rate the quality of life and suffering of their patient relative, and patients provided self-ratings using the same structured instruments. Multivariate cross-sectional and longitudinal analyses were used to identify predictors of caregiver-patient discrepancies.
RESULTS: Caregivers consistently reported significantly higher levels of suffering and lower levels of quality of life than patients. Caregiver psychological well-being and health status accounted for a substantial portion of the difference in caregiver and patient ratings in both cross-sectional and longitudinal analyses. Caregiver depression and burden were consistently positively associated with the magnitude of caregiver-patient discrepancy, and caregiver health status was negatively associated with the size of the discrepancy.
CONCLUSIONS: Caregiver assessments of dementia patients may determine the type and frequency of treatment received by the patient, and caregivers' ability to reliably detect change in patient status can play a critical role in evaluating the efficacy of therapeutic interventions and pharmacologic agents. Clinicians and researchers working with dementia patients who rely on caregiver reports of patient status should be sensitive to the health and well-being of the caregiver and recognize that caregiver assessments may be negatively biased when the caregiver's own well-being is compromised.