Pre Admission Antithrombotics are Associated with Improved Outcomes following Ischaemic Stroke: A Cohort from the Registry of the Canadian Stroke Network

BACKGROUND: Several studies have attempted to identify predictors of outcome following ischaemic stroke. Reduced stroke severity has been reported with pre admission ASA use, and improved outcomes have been reported with pre admission statin treatment. The interaction between pre treatment medications and clinical response to tPA is less clear. The objective of our study was to assess clinical outcomes in patients with acute ischaemic stroke with respect to pre treatment medications. METHODS: The Registry of the Canadian Stroke Network collected pre morbid and prospective outcome data on 5568 patients with ischaemic stroke. We applied multivariate analyses to correlate pre admission medications with stroke severity on presentation, in-hospital mortality, and modified Rankin at discharge. Analyses were adjusted for age, gender, medical history, tPA administration, blood pressure, and glucose on presentation. RESULTS: Pre admission treatment with ASA and clopidogrel was associated with less severe stroke upon presentation. A similar trend was seen with dipyridamole and ticlopidine, but did not reach statistical significance. Pre treatment with ASA and warfarin was associated with improved Rankin scores at discharge. There was no interaction between tPA treatment and pre admission antiplatelets with respect to in-hospital mortality or disability at discharge, although tPA treatment was independently associated with improved Rankin at discharge. Pre treatment antiplatelet use did not result in increased intracerebral haemorrhage following tPA administration. CONCLUSIONS: Patients with acute ischaemic stroke taking antithrombotic medications at hospital admission have improved functional outcomes. No interaction is noted between use of these medications and outcome following thrombolysis. This large prospective cohort study is consistent with previous published reports, and supports the notion that pre admission antithrombotics may mitigate brain injury during acute stroke.