Revised iScore to Predict Outcomes after Acute Ischemic Stroke

Abstract

The iScore is a validated tool to predict mortality and functional outcome after acute ischemic stroke. It incorporates stroke subtype according to the Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification as one of its factors. However, the TOAST stroke subtype may not be easily determined without extensive investigations. We aimed to test if the stroke subtype can be substituted by the Oxfordshire Community Stroke Project (OCSP) classification. We applied the iScore and the revised iScore, in which the TOAST subtype was replaced by the OCSP classification, to patients admitted to a single hospital for acute ischemic stroke. Outcome measures included poor functional status (modified Rankin scale score, 3-6) at discharge and 3 months. The performance between the iScore and the revised iScore was assessed by determining the discrimination and calibration of the scores. We studied 3196 patients at the acute stage, and among them 2349 patients were available for the 3-month assessment. The discrimination of the revised iScore was comparable with the iScore for poor outcome at discharge (area under the receiver operating characteristic curve, .767 versus .775; P=.06) and at 3-month (.801 versus .810; P=.06). The correlation between the observed and the expected outcomes was high for both the iScore (Pearson correlation coefficient, .993 at discharge and .995 at 3 months; both P<.0001) and the revised iScore (.985 and .993, respectively; both P<.0001). The revised iScore reliably predicts clinical outcomes at discharge and 3 months for patients with acute ischemic stroke.