Proxy and self-report agreement on the Stroke and Aphasia Quality of Life Scale-39

Abstract

Background and purpose: Health related quality of life outcomes are increasingly used to measure the effectiveness of stroke interventions. People with severe aphasia after stroke may be unable to self-report on such measures, necessitating the use of proxy respondents. We explored the level of agreement between people with aphasia (PWA) and their proxies on the Stroke and Aphasia Quality of Life Scale (SAQOL-39) and whether this agreement is influenced by demographic variables and proxy levels of depression and carer strain. Methods: People with chronic aphasia (>6 months post stroke) were recruited through the UK national charity for PWA. They were interviewed on the SAQOL-39 and their nominated proxies were interviewed on the SAQOL-39, the General Health Questionnaire and the Caregiver Strain Index. Proxy respondents had to be >18 years of age, see the person with aphasia at least twice a week and have no known severe mental health problems or cognitive decline. Results: 50 of 55 eligible pairs (91%) took part in the study. Proxies rated PWA as more severely affected than PWA rated themselves. The SDs of the difference scores were large and the difference was significant for three of the four SAQOL-39 domains and the overall mean (p(0.01). However, the bias as indicated by effect sizes was small to moderate (0.2-0.5). The strength of the agreement was excellent for the overall SAQOL-39 and the physical domain (intra-class correlation coefficient ICC 0.8), good for the psychosocial and communication domains (0.7) and fair for the energy domain (0.5). Demographic variables and proxy's mood and carer strain did not affect the level of agreement. Conclusions: For group comparisons, proxy respondents who are in frequent contact with people with chronic aphasia can reliably report on their health related quality of life, using the SAQOL-39. Although there are significant differences between PWA and proxy responses, the magnitude of this difference is small to moderate.

Assessment of Depression After Stroke

“…In our study, caregivers rated patients as more depressive than did the patients themselves, although there was some correlation between the caregiver ratings and patient ratings. This result is in line with studies on the quality of life among patients with stroke, 35,36 in which proxies tended to score the patients as more severely affected than the patients scored themselves. In our study, this disagreement 6 and 18 months after stroke was higher when the caregivers themselves had high BDI scores and patients low BDI scores.…”

The assessment for living with aphasia: Reliability and construct validity

“…In one study, ∼ 25% of stroke survivors were excluded from QoL assessment because of aphasia or cognitive impairments (Kwa, Limburg, & de Haan, 1996). For this reason, there is support for proxy judgements in which another person reports for the person with communication disability (Hilari & Byng, 2009;Hilari, Owen, & Farrelly, 2007). However, most caution against proxy judgements on personal or subjective domains (e.g., Carod-Artal, Coral, Trizzoto, & Moreira, 2009).…”

What Factors Predict Who Will Have a Strong Social Network Following a Stroke?

“…People with aphasia are excluded from most stroke research exploring social networks (Northcott et al, 2015). Even where people with aphasia have been included, often researchers have relied on proxies (Astrom et al, 1993;Boden-Albala et al, 2005) although there are concerns that proxy responses are not commensurate with self-report (Hilari, Owen, & Farrelly, 2007). This may potentially bias results: a recent retrospective analysis of pooled clinical trial data (n = 8,904) reported that 45% of stroke survivors initially presented with aphasia, and by three months the aphasia persisted for 24% of stroke survivors (Ali, Lyden, & Brady, 2015).…”