Analysis of the National Institute of Neurological Disorders and Stroke Tissue Plasminogen Activator Studies Following European Cooperative Acute Stroke Study III Patient Selection Criteria

Background: In 1995 two studies by the National Institute of Neurological Disorders and Stroke (NINDS) proved that intravenous tissue plasminogen activator (t-PA) was superior to placebo in patients with stroke of less than 3 hours' duration. The recently published European Cooperative Acute Stroke Study (ECASS) III introduced new patient selection criteria and treatment between 3 and 4.5 hours. Using these criteria, t-PA was shown effective at the later time window. Both analyses used the 3-month modified Rankin scale (mRS) score as main primary outcome. We sought to study the effect of applying the ECASS III selection criteria to the original NINDS cohort. Methods: We analyzed the subgroup of patients from NINDS sample who matched the ECASSS III criteria. We examined 3-month outcomes adjusted and unadjusted for confounding factors. Results: The NINDS t-PA study included 624 patients. A total of 200 in the t-PA-treated group and 199 in the placebo group were selected after applying ECASS III criteria. Of these selected patients, 52% in the t-PA group versus 31% had mRS score of 0 or 1 at 3 months (P < .001). The unadjusted odds ratio for t-PA treatment versus placebo on day-90 mRS score 0 to 1 versus 2 to 6 was 2.45 (95% confidence interval: 1.63-3.69). When adjusted for baseline National Institutes of Health Stroke Scale score, smoking status, time to treatment, and history of hypertension, the odds ratio was 2.14 (95% confidence interval: 1.34-3.41) (P < .001). Conclusion: Using the ECASS III criteria in patients treated in less than 3 hours, 52% of t-PA-treated patients had a favorable outcome at 3 months.