The iScore Predicts Efficacy and Risk of Bleeding in the National Institute of Neurological Disorders and Stroke Tissue Plasminogen Activator Stroke Trial

The iScore is a validated tool to estimate outcomes after an acute ischemic stroke. A previous study showed the iScore can predict clinical response and risk of intracerebral hemorrhage (ICH) after administration of tissue plasminogen activator (tPA). We applied the iScore (www.sorcan.ca/iscore) to participants in the National Institute of Neurological Disorders and Stroke tPA stroke trials to evaluate its ability to estimate clinical response and risk of ICH after thrombolysis. Based on results from our previous study, patients were stratified a priori into iScore <200 and iScore >= 200. The main outcome measure was ICH. Secondary outcomes included favorable composite outcome (defined as a modified Rankin Scale score of 0 or 1, National Institutes of Health Stroke Scale score <= 1, Barthel Index >= 95, or Glasgow Outcome Scale,1 at 3 months) and functional outcomes. The iScore was calculated in all 624 patients enrolled in the trial. The cohort comprised 507 patients (81%) with an iScore <200 and 117 (19%) with an iScore >= 200. An iScore >= 200 was associated with greater risk of symptomatic ICH in the tPA group compared with the placebo group (15.4% v 3.9%; P = .04). Similar findings were found for ICH of any type (30.8% v 11.5%; P = .014), with higher ICH mortality (69.2% v 23.8%; P < .001). Despite the higher favorable composite outcome of tPA therapy in patients with an iScore <200 (58.7% v 41.9%; P < .001), this therapy had no benefit in patients with an iScore <200 (15.4% v 13.4%; P = .77). In patients receiving tPA in the National Institute of Neurological Disorders and Stroke trial, the iScore estimated the clinical response and risk of hemorrhagic complications. Further prospective studies are needed before a change in practice can be recommended.