STT: Stroke Thrombolysis Trialists' Collaboration
Thrombolytic therapy (or ‘clot-busting’ treatment) with intravenous (iv) recombinant tissue plasminogen activator (rt-PA, alteplase) is the only approved acute medical treatment for ischemic stroke.
Previous analyses of pooled data from randomised trials concluded that rt-PA is beneficial when administered to particular types of patient within 4.5 hours, but that the magnitude of benefit diminishes with increasing treatment delay. The Stroke Thrombolysis Treatment (STT) Collaboration was formed by scientists who had coordinated trials of rt-PA in acute stroke. They agreed to make their individual-patient-data available for a pooled statistical analysis and published a Statistical Analysis Plan before commencing pooled analyses.
The main goal of this analysis was to explore the extent to which treatment delay influenced the effect of rt-PA and to determine whether age or stroke severity influenced treatment effects. The results showed that Irrespective of age or stroke severity, and despite the early risk from intracerebral hemorrhage, rt-PA significantly improved the odds of surviving with no significant disability when delivered within 4.5 hours of stroke onset. These results helped to guide the work of the UK Commission on Human Medicine’s Expert Working Group, which was asked to examine all of the available evidence on rt-PA for acute stroke. The slides presented at the Expert Working Group’s 3 meetings in 2014-5 may be found here.
More recent analyses have explored the effects of rt-PA on intracerebral haemorrhage, and provided more detailed information on how treatment influences the degree of disability after stroke.