Abstract 2524: Increasing the Proportion of Patients Treated with Stroke Thrombolysis: Reducing In-hospital Delays has Substantially More Impact than Extension of the Time Window

Abstract

Background Pooled analyses show the benefit of IV alteplase for ischemic stroke up to 4·5 hours after onset, and expert guidelines have been updated to reflect this. However, the benefit from thrombolysis is critically time-dependent, and the additional benefit from extending the time window may be jeopardised by in-hospital delays. Methods We developed a discrete-event simulation based on prospective data from 1142 acute stroke patients arriving at our large district hospital over a two-year period to April 2011, modelling the time spent in the ED for triage and assessment, brain imaging and, if applicable, thrombolysis. Outputs from the model included arrival to treatment times (ATT), percentage of strokes thrombolysed, and the number of thrombolysed patients with a 90 day modified Rankin Scale (mRS) of 0-1. We sought to model the current stroke pathway (treatment <3 hours of onset), and compare it with developmental scenarios exploring the impact of extending treatment from 3 to 4.5 hours, of ED staff alerting the stroke service at triage, of ambulance pre-alert to the stroke service, and combinations of these measures. Results The model illustrates that extending the treatment window modestly increases the percentage of acute strokes thrombolysed, from 5% to 6% (95% CI 5.8-6.1%), and increases the number of thrombolysed patients with mRS 0-1 by 7 per year (95% CI 5.9-8.0). Both the triage alert and ambulance pre-alert scenarios increase thrombolysis rates to 15% (95% CI 14.9% to 15.7%); but the ambulance pre-alert reduces ATT by a mean of 27 mins (95% CI 26.3-28.4) compared to the triage alert scenario. The ambulance pre-alert scenario increases the number of thrombolysed patients with mRS 0-1 by 35/year (95% CI 32.9-37.7) compared to 22 (95% CI 20.4-23.5) in the triage alert scenario. Combining the treatment extension with either alerting measure does not increase the thrombolysis rate further (15%, 95% CI 14.7-15.1%). Sensitivity analysis illustrates that the pre-alert system is the least vulnerable to a drop in compliance rates. Conclusions Our simulation model shows that the greatest disability benefit accrues from measures to substantially reduce in-hospital delays to alteplase treatment - a potential three-fold increase in the proportion of patients treated. Compared to extending the time window for alteplase from 3 to 4.5 hours, eradicating in-hospital delays to treatment offers a five-fold greater disability benefit, and this should be the pre-eminent focus of service improvement for all emergency receiving hospitals.