Abstract 281: The RACE scale for Large Vessel Stroke Diversion to Comprehensive Center by Helicopter Air Ambulance

Abstract

Introduction Acute ischemic stroke caused by large vessel occlusion (LVO) occurs frequently and benefits from endovascular therapies available at comprehensive stroke centers (CSC) {Goyal 2016} {Lakomkin, 2019}. Real world evidence shows that endovascular therapy is effective and better than tPA in cases of LVO {Noguria 2016}. Comprehensive stroke centers are also faster at administering tPA and have better tPA metrics for patients with LVO compared to transfers from non CSCs{Shumei M, 2018}{Seker 2020}. Evidence shows that direct transport to an interventional center may provide benefit even if they are not the closest hospital {Benoit J, 2018} {Venema 2020}. Prehospital stroke severity tools such as the RACE scale and others have been devised to detect LVO with reasonable sensitivity and specificity {Krebs 2018} {Dickson 2020}. Helicopter Air Ambulances (HAA) can limit the time to comprehensive stroke care for rural communities {Liera 2016}. Following the recommendations of the American Stroke Society (ASA), regional EMS protocol allow for direct transfer for potential LVO cases within 24 hours by HAA.{NWOEMS consortium protocol}{Powers WJ 2019}. For this reason HAA can enhance access to comprehensive stroke centers into rural communities. Methods A retrospective assessment of RACE scales of 5 or greater performed by prehospital providers was used in order to activate HAA. Descriptive statistics were obtained for patients transported with primary goal of determining the positive predictive values of the RACE Scale for LVO occlusions. Secondary outcomes were if patients had other conditions requiring a comprehensive stroke center. Results Data from 148 subjects were in the research dataset. Twelve of these were eliminated due to not meeting inclusion criteria, death prior to imaging, and transport to another facility where records were not available. This resulted in analyses from 136 subjects. Of the 136, 53 (39.0%) were true LVO cases as defined by CT, CTA imaging or MRI. There were 83 (61%) falsely positive (no LVO on imaging). Mechanical thrombectomy occurred in 30 cases (22.1%) with 63 (46.4%) requiring a neurologic intervention. Conclusion When the RACE scale is used in real world EMS practice to triage rural stroke cases, it has a high positive predictive for HAA activation with delivery to a comprehensive stroke center in suspected stroke cases. Even false positive activations required care at a comprehensive stroke center in most case.