Abstract 96: Assessment of the Rapid Arterial oCclusion Evaluation (RACE) Scale in Real-World Practice for Prediction of Large Vessel Occlusion and Reducing Time to Thrombectomy

Abstract

Background: Pre-hospital identification of potential large vessel occlusion (LVO) stroke patients may lead to faster triage and treatment. We examined whether the RACE scale can be reliably implemented in a real-world setting with multiple EMS agencies and lead to rapid treatment. Methods: A prospective study was performed at a high volume comprehensive stroke center. In the first phase, eight EMS agencies were educated on use of the RACE scale using an online training video. All EMS stroke alerts were recorded. When EMS RACE score was 5 or higher, the neurocath lab team was alerted prior to EMS arrival as part of a parallel workflow. Upon ER arrival, the following characteristics were tracked: NIHSS score, RACE score, CT findings, presence of LVO and workflow time metrics. Results: During the study period (January 2016 to June 2017), RACE score was provided for 797 of 1498 EMS stroke alerts (53%). Higher pre-hospital RACE scores correlated with NIHSS scores. LVO was found in 106 (13%) of patients with an available RACE score. A RACE score of 5 or higher was able to identify 64% of all LVO patients (sensitivity: 64%; specificity: 72%; PPV: 30%; NPV: 93%; accuracy: 71%; Youden’s index). However, of the 260 patients with RACE score 5 or higher, only 68 patients (26%) were found to have LVO while 29 patients (11%) had ICH (figure); among 499 patients with RACE score less than 5, LVO was present in 38 patients (8%). When an EMS stroke alert with high RACE score triggered early alert of the neurocath lab team, median door to groin puncture time for thrombectomy was 65 minutes compared to 91 minutes for cases with sequential workflow. Conclusion: The RACE scale can be successfully implemented across EMS agencies and results in faster door to groin puncture times. While a RACE score of 5 or higher is associated with greater likelihood of LVO, there are a significant number of false positives. Further refinement of pre-hospital stroke severity scales is warranted to improve the accuracy of this approach.