Agreement between stroke patients' and proxy assessments of health-related quality of life

Abstract

Background: Stroke has become the second most cause of death and leading cause of disability worldwide. Patients-reported health related quality of life measures are often used in evaluating stroke outcomes. However, many stroke patients can not participate in the outcome assessments due to severe disability or aphasia or cognitive impairment. In this case, proxy respondents can be used as secondary information sources. The principle thing needs to be paid attention to in using proxy’s assessments is the reliability or agreement between patient and proxy. Western studies have shown that the agreement between patient and proxy was moderate to substantial. However, such studies are limited in China. Simply applying overseas research outcomes on local population is not appropriate. Therefore, we conducted this study to find out the agreement between stroke patients and proxy assessments about quality of life in China.

Methods: 100 patient-proxy pairs were enrolled in our study. Our study was a hospital-based study. The included patients were 3 months after stroke, and patients with more than moderate aphasia or cognitive impairment were excluded. Proxies were people who knew the patients > 1 year, contacted with the patients ≥ 3 days per week, were responsible for ≥ 2 caregiving tasks, and ≥ 18 years. The Chinese version of Stroke-specific quality of life scale (SS-QoL) was used to assess the stroke patients’ QoL, and proxy version of SS-QoL was used in proxies’ evaluation. The evaluation process of patient and proxy was separately and concurrently. Method of self-reported combined with interview-administered was adopted. Paired t tests or Wilcoxon signed ranks tests were performed to test the systematic differences between patient and proxy. The agreement level between patient and proxy assessments on stroke QoL was estimated by Intraclass correlation coefficient (ICC). Multiple linear regression was performed to find out factors affecting the patient-proxy agreement.

Results: Patients were older (61 versus 48 years) and more often male (63% versus 44%). Mean systematic differences ranged from 0.03 to 0.44. Only 3 domains of differences were statistical significant (Language, Personality, and Work/productivity). The strength of agreement between patient and proxy reporting ranged from fair to perfect (ICC: 0.31 to 0.87). Better agreement was observed in more objective domains while worse agreement was reported in more subjective domains. Proxy education was tested to be a significant predictor of the overall patient-proxy score difference, which indicated that higher proxy education level was associated with greater agreement. It was shown that higher overall patient-reported or proxy-reported SS-QoL score was associated with less stroke impairments. Factors of stroke impairments, patient/proxy education level, patient/proxy gender, and stroke type separately have significant impacts on the agreement between patient and proxy in different domains of QoL.

Conclusion: Our findings indicate that proxies may provide reliable information for assessments about stroke patients’ quality of life in China. And the outcomes are more appropriate for mind to moderate stroke patients. For further studies, the reliability of proxy information about severe stroke patients should be paid attention to. Research about changes of agreement between patient and proxy along with the disease development process would be focused on.