How do scores on the EuroQol relate to scores on the SF-36 after stroke?

Background and Purpose-The EuroQol and Medical Outcome Survey 36-item short -form health survey (SF-36) questionnaires have both been validated for the assessment of health-related quality of life after stroke. However, the re lationship between these instruments has not been studied after stroke. We therefore sought to compare the responses of a group of stroke patients to both instruments. Methods-A total of 2253 patients with stroke entered by United Kingdom hosp itals in the International Stroke Trial were randomized to follow-up with e ither the EuroQol or SF-36 instruments. We randomly selected one third of p atients who had responded to the EuroQol for follow-up, again using the SF- 36, and two thirds of patients who had responded to the SF-36 for follow-up , again using the EuroQol. We assessed the patients' mean score for each do main of the SF-36 categorized by their response to the corresponding EuroQo l domain and the con-elation between the domains of the 2 instruments. Results-The domains for both instruments, which assessed physical functioni ng, social functioning, bodily pain, and overall health-related quality of life, correlated closely. The mental health domain of the SF-36 correlated only poorly with the psychological functioning domain of the EuroQol, Conclusions-Both the EuroQol and SF-36 measure broadly similar domains of h ealth. The weak relationship between the assessments of mental health may r eflect a difference in content or more fundamental problems with the validi ty or reliability of the items in one of the instruments with respect to th is domain. This study has provided the first empirical qualitative evidence by which the data on the SF-36 after stroke may be interpreted.