The iScore Predicts Poor Functional Outcomes Early After Hospitalization for an Acute Ischemic Stroke

Abstract

Background and Purpose— The iScore is a prediction tool originally developed to estimate the risk of death after hospitalization for an acute ischemic stroke. Our objective was to determine whether the iScore could also predict poor functional outcomes. Methods— We applied the iScore to patients presenting with an acute ischemic stroke at multiple hospitals in Ontario, Canada, between 2003 and 2008, who had been identified from the Registry of the Canadian Stroke Network regional stroke center database (n=3818) and from an external data set, the Registry of the Canadian Stroke Network Ontario Stroke Audit (n=4635). Patients were excluded if they were included in the sample used to develop and validate the initial iScore. Poor functional outcomes were defined as: (1) death at 30 days or disability at discharge, in which disability was defined as having a modified Rankin Scale 3 to 5; and (2) death at 30 days or institutionalization at discharge. Results— The prevalence of poor functional outcomes in the Registry of the Canadian Stroke Network and the Ontario Stroke Audit, respectively, were 55.7% and 44.1% for death at 30 days or disability at discharge and 16.9% and 16.2%, respectively, for death at 30 days or institutionalization at discharge. The iScore stratified the risk of poor outcomes in low- and high-risk individuals. Observed versus predicted outcomes showed high correlations: 0.988 and 0.940 for mortality or disability and 0.985 and 0.993 for mortality or institutionalization in the Registry of the Canadian Stroke Network and Ontario Stroke Audit cohorts. Conclusions— The iScore can be used to estimate the risk of death or a poor functional outcome after an acute ischemic stroke.