Differences between patient and caregiver ratings of advanced cancer patients' quality of life and correlates of their disagreement

Abstract

Background: Assessment of patient quality of life (QoL) by surrogates, particularly informal caregivers (e.g. spouse), is important to the care of advanced cancer patients. However, accuracy of such surrogate QoL assessments has been questioned. This study sought to assess differences between patients’ QoL self-assessments compared to assessments by their informal caregivers, and to determine characteristics associated with the disagreement. Methods: Data from 570 advanced cancer patient-caregiver dyads participating in the multi-site, Coping with Cancer study were included. Patients assessed their QoL with the McGill QoL questionnaire. Caregivers estimated patients’ QoL using the same questionnaire. Paired t-tests were used to compare the dyadic estimates of QoL scores. Multiple linear regression (MVA) was performed to examine factors potentially associated with the difference in dyadic QoL estimates. Results: Caregivers’ mean age was 53 years, 71% were female, and 51% were spouses. The overall mean patient QoL score, as assessed by caregivers, was lower than the overall mean QoL by patient assessment [6.4 (SD=1.8) vs. 7.1 (SD=1.6), p<.0001]. In MVA assessing factors contributing to patient-caregiver differences in QOL assessment, sociodemographic factors, overall coping, positive religious coping, and interpersonal support were not associated with any significant disagreement. Higher level of caregiver negative religious coping (β=.31, p=.0002) and burden (β=.77, p<.001), lower caregiver self-efficacy (β=-.54, p=.005), higher stressful caregiving adult reactions to experiences of dying scale (SCARED) (β=1.28, p<.0001) and higher patient self-estimated QoL (β=2.92, p<.0001) were significantly associated with greater disagreement between patient and caregiver estimates of patient QoL. Conclusions: Caregiver assessments of patient QoL are underestimated as compared to patient self-assessment. Caregiver factors, including negative religious coping, self-efficacy, burden and SCARED, are associated with patient-caregiver disagreement in estimates of patient QoL, suggesting ways to improve accuracy of caregivers’ evaluation of patient QoL.