Agreement between patient and proxy assessments of health-related quality of life after stroke using the EQ-5D and health utilities index

Background and Purpose - Proxy informants can provide information on patients who are limited in ability to self-assess health-related quality of life (HRQL) after stroke. One alternative is to exclude assessments of such patients and attenuate generalizability. The purpose of this study was to examine patient-proxy agreement on the domains and summary scores of the EQ-5D and Health Utilities Index Mark 3 (HUI3) after stroke. Methods - An observational longitudinal cohort of 124 patients hospitalized after ischemic stroke and their family caregivers completed the HRQL measures at baseline and were followed up for 6 months. Patient and proxy agreement was assessed by use of weighted kappa or the intraclass correlation coefficient (ICC). Results - At baseline, the more observable domains of HRQL demonstrated greater agreement than the more subjective components. Cross-sectional point estimates of agreement were generally acceptable ( ICC > 0.70) for the EQ-5D Index and HUI3 summary scores when assessed greater than or equal to 1 month after baseline. Agreement between change scores was generally poor to fair ( ICC < 0.60), but systematic bias was not observed for the indirect preference-based summary scores between baseline and 6 months. Conclusions - Results suggest that proxy assessments obtained 6 months after stroke are more reliable than those obtained within 2 to 3 weeks after stroke. Although proxy-assessed change scores for indirect preference-based summary scores of the EQ-5D and HUI3 provided suboptimal agreement with patient assessment, limited systematic bias may support their consideration as alternatives to missing data or statistical imputation. Further research into the validity and reliability of proxy assessments is suggested.