Concordance of quality-of-life assessments between terminally ill cancer patients and their primary family caregivers in Taiwan.

Physical or cognitive deterioration may hamper the ability or willingness of cancer patients to participate and remain in quality-of-life (QOL) research at the end of life. Use of family caregivers as proxy informants to report patients' QOL has been suggested as a way of resolving the problem of nonresponse bias and nonrandom missing data in end-of-life research. However, there is a dearth of information in the literature about the extent of concordance of QOL assessments between terminally ill patients and their family caregivers outside Western countries. A prospective and descriptive study was conducted to fill the gap in the literature. Results from 114 dyads of Taiwanese terminally ill cancer patients and their family caregivers indicated that QOL assessments from family informants agreed at least moderately well with patients' QOL reports. None of the standardized absolute mean differences for individual items and composite (sub)scales between the 2 respondents exceed the threshold of moderate (>0.50) set by Cohen. Generally, when discrepancies existed, family caregivers held a more negative view of patients' QOL than did patients. At the individual patient level, family caregivers were best able to assess functional dependency, followed by symptom distress, but were least reliable when evaluating the psychological-social-spiritual concerns of patients. The conclusion made by Western researchers that family caregivers can act as a not perfect but reliable alternative source of QOL data for terminally ill cancer patients who are no longer able to speak for themselves is cross-culturally confirmed in this study. It is suggested from the findings that, for family caregivers to function well in their role as proxy informants on the psychological reactions and social/spiritual domains of QOL as well as surrogate decision makers for terminally ill cancer patients in Asian countries, an open and frequent dialogue between terminally ill cancer patients and their family caregivers should become standard.