Abstract 58: The Iscore Predicts Efficacy Of Thrombolytic Therapy For Acute Ischemic Stroke

Abstract

Background: The iScore is a validated tool developed to estimate the risk of death and functional outcomes early after an acute ischemic stroke. It includes demographics, stroke severity and subtype, vascular risk factors, cancer, renal failure, and pre-admission functional status. Limited information is available to predict the clinical response after intravenous thrombolytic therapy (tPA). Objective: To determine the ability of the iScore to predict the clinical response and risk of hemorrhagic transformation after tPA. Methods: We applied the iScore ( www.sorcan.ca/iscore ) to patients presenting with an acute ischemic stroke at 11 stroke centres in Ontario, Canada, between 2003 and 2008, identified from the Registry of the Canadian Stroke Network (RCSN). We compared outcomes between patients receiving and not receiving tPA adjusting for differences in baseline characteristics through matching by propensity scores. Three groups were defined a priori as per the iScore (low risk 180). Outcome Measures: Poor outcome, the primary outcome measure, was defined as disability at discharge or death at 30 days. Secondary outcomes included disability at discharge, neurological deterioration and intracranial hemorrhage (any type and symptomatic). Results: Among 12,686 patients with an acute ischemic stroke, 1696 (13.4%) received intravenous thrombolysis. Overall, 589 tPA patients were matched with 589 non-tPA patients (low iScore risk), 682 tPA were matched with 682 non-tPA patients (medium iScore risk) and 419 tPA patients were matched with 419 non-tPA patients (high iScore risk). There was good matching in all three groups. Higher iScore was associated with poor functional outcome in both the tPA and non-tPA groups (p<0.001). Among those with low and medium iScore risk, tPA use was associated with lower risk of poor outcome (Low iScore RR 0.74; 95%CI 0.67-0.84; medium iScore RR 0.88; 95%CI 0.84-0.93). There was no difference in clinical outcomes between matched patients receiving and not receiving tPA in the highest iScore group (RR 0.97; 95%CI 0.94-1.01). Similar results were observed for disability at discharge and length of stay. The incident risk of neurological deterioration and hemorrhagic transformation (any or symptomatic) increased with the iScore risk ( Figure ). Conclusion: The iScore appears to predict clinical response and risk of hemorrhagic complications after tPA for an acute ischemic stroke. Patients with high iScores may not benefit from tPA and have higher risk of hemorrhagic transformation, though this finding should be validated independently (underway) before clinical use.