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.