Are the modified "simple questions" a valid and reliable measure of healthrelated quality of life after stroke?

Objectives-Two "simple questions" were developed as a minimalist measuremen t tool to assess outcome in large trials and epidemiological studies after stroke. A previous study of their validity had disclosed ambiguities in the ir wording. In this study, the clarity, validity, and reliability of a modi fied version of these simple questions were examined. The relation between patients' responses to these questions and two widely used generic measures of health related quality of Life were also studied. Methods-A hospital based stroke register cohort of 152 patients, who were a ll visited at home by a study nurse, was used to study validity. A cohort o f 1753 patients derived from the International Stroke Trial was used to stu dy the relation with measures of quality of life. The sensitivity, specific ity, and accuracy with which responses to each question predicted the patie nts' outcome measured using standard instruments was assessed. The distribu tion of scores for the EuroQol and SF-36 was examined for patients classifi ed as dependent, independent, and fully recovered by the combined use of th e modified simple questions. Results-The modified "dependency" question had excellent sensitivity (>85%) , specificity (>79%), and accuracy (>82%) for identifying dependency after stroke. The "problems" question had good sensitivity (65-88%) and moderate specificity (36-72%) for the detection of problems in a broad range of doma ins. The combined use of the modified dependency and problems questions pro vided a valid, simple, and reliable overall indicator of health related qua lity of life after stroke. Conclusions-The modified simple questions have excellent face validity and good measurement properties for the assessment of outcome after stroke. The y are particularly well suited for large epidemiological studies and random ised trials.