Abstract WP246: Time of Onset of Acute Ischemic Stroke As Determined by EMS Personnel is Congruent With Physician-Determined Time of Onset

Abstract

Background: Finding witnesses for determination of acute ischemic stroke (AIS) time of onset (ToO) is often time-consuming and prolongs door-to-needle time (DNT). Physicians are reluctant to trust the ToO provided by EMS personnel due to little data available on its accuracy. We measured the congruence of EMS-provided ToO relative to physician-determined ToO in suspected AIS patients presenting to the emergency department (ED). Methods: From March 2010 to September 2011, research coordinators prospectively collected the EMS-provided ToO for each arriving acute stroke patient. The difference between the EMS-provided ToO and physician-determined ToO was calculated for each patient. Summary statistics were examined for the entire patient cohort and the subgroup of tPA-treated patients. Results: Of the 209 acute stroke alerts, the absolute mean difference in EMS- and physician-ToOs was 16 ± 80 min (median [IQR] = 0 [0,0] min). EMS- vs. physician-ToO was congruent within 15 min 87% of the time. Figure shows histogram of absolute differences for the cohort. Of the 46 patients with any difference (≥1 min) in ToO’s, only 2 patients (4.3%) could have been given tPA incorrectly if EMS-provided time had been used (solely based on time-related inclusion criteria for IV tPA up to 4.5 hours). In the subgroup of IV tPA-treated patients (N=40) the absolute mean difference in EMS- and physician-ToOs was 10 ± 27 min (median [IQR] = 0 [0,2.8] min) and were congruent within 15 minutes 88% of the time. None of these patients would have been incorrectly excluded from tPA if EMS-provided times had been used. Conclusions: In this convenience sample, EMS-provided ToOs were similar to physician-determined ToOs and. If EMS times had been used in place of physician-determined times, this might have resulted in a 1% tPA error rate. Given that determining the ToO often leads to delays in tPA delivery, further studies are needed to confirm that EMS- ToO’s are reliable for clinical decision-making.