Abstract WP288: Impact of Prehospital LVO Tools on the Delay of Care and Redistribution of Patients between Primary and Comprehensive Stroke Centers

Abstract

Introduction: Several tools have been developed aimed at predicting large vessel occlusion (LVO) in the prehospital setting. If these tools are used to bypass Alteplase-but-not-thrombectomy-capable hospitals, this would speed the care for some patients, delay it for others, and unnecessarily redistribute some patients between hospitals. Methods: We examined a hypothetical scenario of 1,000 patients evaluated by EMS for possible stroke. We used data published by RACE (Rapid Arterial oCclusion Evaluation) that included 357 patients to calculate the rates of the different stroke subtypes. Ischemic stroke represented 67.2% of patients, hemorrhagic stroke 14.6%, transient ischemic attack 5.6%, and stroke mimic 12.6%. We applied the following assumptions: rate of LVO as 20% of total ischemic stroke, all patients evaluated by EMS within 3 hours from their last known well time with a rate of tPA utilization is 50%, endovascular-capable hospital is further away, similar door-to-needle (DTN) time in all hospitals, delay in DTN in false positive patients, and delay in door-to-groin time (DTG) in false negative patients. Seven tools were studied using published values for sensitivity and specificity. Results: Using no tools would lead to evaluation of all patients at the nearer hospital first, leading to delay in DTG of all 134 LVO patients, however no delay in DTN. Comparing the various tools, DTN delay would be highest with Cincinnati Prehospital Stroke Severity Scale (CPSSS; n=175) and least with 3-item stroke scale (3I-SS; n=23). DTG delay would be highest with Prehospital Acute Stroke Severity (PASS) and Field Assessment Stroke Triage for Emergency Destination (FAST-ED) (n=52 for both) and least with RACE (n=20). Redistribution of patients would be highest with CPSSS and lowest with 3I-SS (reduction in patient volume to non-thrombectomy capable hospital 63% and 16% respectively and increase in volume for the thrombectomy-capable hospital by 371% and 19% respectively). Conclusion: Current tools have a very wide variation in performance. Although some tools would likely reduce the delay in DTG time for most (but not all) LVO patients, they risk delaying care for other patients and may cause an unnecessary redistribution of patients between hospitals.