Measuring Quality of Life in Residential Aged Care Using the EQ-5D-5L: A Cross-Sectional Study on the Impact of Cognition Level and Proxy Perspective on Interrater Agreement

Quality of life (QoL) is an important outcome in aged care, but self-report is not always possible due to the high prevalence of cognitive impairment in older aged care residents. This study aims to assess the impact of family member proxy perspective (proxy-proxy or proxy-person) on interrater agreement with resident self-report by different cognition levels. The influence of proxy perspective and cognition level is a significant gap in the extant literature which this study seeks to address. A cross-sectional study was undertaken with residents classified into cognition subgroups according to the Mini Mental State Examination. Residents completed the self-report EQ-5D-5L, a well-established generic measure of health-related quality of life (HRQoL). Family member proxies completed EQ-5D-5L proxy version 1 (proxy-proxy perspective, where the proxy responds based on their own opinions) and proxy version 2 (proxy-person perspective, where the proxy responds as they believe the person would). Interrater agreement was assessed using the concordance correlation coefficient (CCC) for utility scores and the weighted kappa for dimension-level responses. Sixty-three residents (n = 22 no cognitive impairment, n = 27 mild impairment, and n = 14 moderate impairment) and proxies participated. EQ-5D-5L utility scores were lower for proxies compared with residents (self-report = 0.522, proxy-proxy = 0.299, and proxy-person = 0.408). Interrater agreement with self-report was higher for proxy-person (CCC = 0.691) than for proxy-proxy (CCC = 0.609). Agreement at the dimension level was higher for more easily observable dimensions, such as mobility, compared to less observable dimensions, such as anxiety/depression. Resident self-reported and proxy family member-reported HRQoL assessments, using the EQ-5D-5L, are different but may be more closely aligned when the proxy is specifically guided to respond from the person’s perspective. Further research is needed to address the impact of divergences in self-report and proxy-report ratings of HRQoL for quality assessment and economic evaluation in aged care.