Time to treatment with recombinant tissue plasminogen activator and outcome of stroke in clinical practice: retrospective analysis of hospital quality assurance data with comparison with results from randomised clinical trials.

4 For the 576 patients treated after than 4.5 hours after onset the analysis failed to show a significant benefit of thrombolytic therapy, despite a non-significant trend towards a better outcome (number needed to treat 21.7, 95% confidence interval for odds ratio 0.9 to 1.6) and an increase in mortality of borderline significance, whereas the third international stroke trial (IST-3) suggested some clinical efficacy up to six hours, also associated with a signal of increased mortality. 5 A subsequent pooled analysis of the previous trials with the individual patient dataset from the third international stroke trial (IST-3) (

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