Reported activities of daily living: agreement between elderly subjects with and without dementia and their caregivers.

OBJECTIVES: to determine how accurately information on disability provided by a caregiver (proxy respondent) reflected the opinion of subjects themselves, and if this agreement varied by severity of dementia or relationship of the caregiver to the subject. SETTING AND PARTICIPANTS: the study was based on data from the Canadian Study of Health and Aging, a multicentre study of dementia and health of Canadians age 65 and over. Eight hundred study subjects and their caregivers were independently interviewed regarding the subjects' activities of daily living (ADL). MEASUREMENTS: the percentage of subjects who were independent for individual ADL items and the agreement in these reports between subjects and caregivers were investigated using three-level kappa statistics.
RESULTS: index subjects with caregivers other than spouses or offspring required more assistance with ADL. The reported percentage of independence decreased with increasing severity of dementia. There was more agreement between self- and proxy-reported level of independence for physical ADL than for instrumental ADL items. Agreement decreased with increasing severity of dementia. Few statistically significant differences were noted between level of agreement and caregiver relationship.
CONCLUSION: satisfactory levels of agreement on ADL between cognitively normal subjects and their caregivers indicate that proxy respondents are a reasonable source of information on ADL when data collection from the subjects themselves is not feasible. Since agreement decreases as the severity of dementia increases, caregiver reports may be preferred for elderly patients even with mild dementia in order to facilitate longitudinal assessment of ADL ratings as the dementia progresses.