Are proxy assessments of health status after stroke with the EuroQol questionnaire feasible, accurate, and unbiased?

BACKGROUND AND PURPOSE It is often difficult to determine the health-related quality of life (HRQoL) of stroke patients because physical and cognitive problems limit their ability to complete complex questionnaires. A proxy, such as a family member or caregiver, may be able to give an estimate of the patients' health status. We therefore examined the agreement between the HRQoL as assessed by a series of patients and that assessed by their proxies. METHODS We studied the validity of the EuroQol in a series of 152 patients from our prospective registry of patients with first (or recurrent) stroke. We asked patients to ensure that a friend or relative (a proxy) who knew them well was available at the time of the interview. We asked each proxy to complete a EuroQol questionnaire independently on behalf of the patient. RESULTS Proxies completed forms for 130 patients (86%). Agreement between responses from the patients and those from their proxies was better for patients who were able to self-complete the EuroQol than for patients who required the EuroQol to be administered by interview. For both groups, agreement was best for the self-care domain and worst for the domain that assessed psychological outcome. For the more severely affected patients, agreement was only fair for the pain and social functioning domains and no better than chance alone for the psychological functioning domain (kappa = 0.05, 95% confidence interval, 0 to 0.43). Patients tended to rate their own health status as better than their proxies did (P < .05). CONCLUSIONS We found moderate agreement between responses from patients and those from their proxies for the more directly observable domains of the EuroQol. Proxy agreement was less good for the more subjective domains. In health surveys, allowing responses by a proxy increases response rate. However, the disadvantages inherent in the use of proxy responses must be considered carefully. In general, some domains of HRQoL information obtained from a proxy may be sufficiently valid and unbiased to be useable in most types of trials and surveys.