Determinants of the discrepancy in patient- and caregiver-rated quality of life for persons with dementia.

Aims: To determine factors related to the discrepancy in patient- and proxy-rated quality of life for patients with dementia; whether this discrepancy is associated with characteristics of patients, caregivers or the caregiver-patient relationship; and which characteristics best predict this discrepancy.

Background: To increase the reliability of quality of life measurements for persons with dementia, many researchers have incorporated proxy reports. However, their investigations have indicated that caregiver-rated quality of life is not the same as the patient's own rating. The factors related to this discrepancy have previously been explored, but studies rarely focussed on the quality of the caregiver-patient relationship as a determinant of the discrepancy.

Design: A cross-sectional design was used.

Methods: Data were gathered from community-based interviews with 120 dyads of patients with Alzheimer's disease or related dementia and their caregivers in Taipei. A structured questionnaire was used to collect data, and the main variable (quality of life-Alzheimer's disease) was rated separately by patients and caregivers. The data were analysed using intraclass correlation coefficients and multivariate regression methods.

Results: The agreement between patients' and caregivers' quality of life-Alzheimer's disease ratings was low. This discrepancy was significantly associated with disturbing dementia behaviour, caregivers' perceived distress for problem behaviours, caregivers' overall quality of life and quality of the caregiver-patient relationship.

Conclusions: The observed discrepancy between caregiver- and patient-rated quality of life for persons with dementia was largely predicted by the quality of the caregiver-patient relationship.

Relevance To Clinical Practice: Medical professionals should cautiously deliberate when using caregiver-reported quality of life to substitute for patient-reported quality of life. When using a proxy report or a combined caregiver-patient rating, medical professionals should assess the quality of the relationship between patient and proxy.