Proxy-reported quality of life in Alzheimer's patients: Comparison of clinical and population-based samples

Prior research has shown the reliability and construct validity of a proxy-reported measure of QoL in AD that involves observed affect and reports of participation in simple, caregiver-guided activities. The measure was developed in a nonminority, clinic sample. We had an opportunity to field the measure in a primarily minority, population-based sample of elders meeting criteria for AD (n = 196). In the population-based sample, proxy-reported patient activity and dementia severity were highly correlated, at levels comparable to those observed in the clinic sample. Relationships between proxy-reported affect and activity in patients, however, were less robust than those observed in the clinic sample. Also, correlations between reported affect and severity of dementia were weaker in the population sample. In comparisons that controlled for Severity of dementia, patients in the primarily low-income, minority community sample were less likely to meet criteria for high QoL than clinic sample patients. Variation in proxy- reported QoL across the two samples can be attributed to a number of factors: greater heterogeneity in sources of dementia in the population-based sample, greater prevalence of paraprofessionals serving as proxies in the population- based sample, and differences in environment that may be relevant for QoL in AD.