LAUSR

of MCA, or basilar artery (BA). We used SAS and c-statistics to create receiver-operating characteristic (ROC) curves to determine the area under the curve (AUC) and optimal score cut point (CP) for each scale. We also calculated the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and overall accuracy for each optimal CP score. Results 250 subjects were enrolled, 17 were excluded for lack of neurovascular imaging, 1 was excluded for incomplete stroke scale data, leaving 232 subjects who met inclusion criteria for analysis. 31 subjects had LVO and the prevalence of LVO was 13.4%. In table 1, we report the performance of each stroke severity scale at their respective optimal CP. In our study, the optimal CP for RACE was 6 while the original RACE study was 5. Conclusions This large, US-based, prospective, pre-hospital, EMS-administered study showed greater AUC for RACE. However, all three scales were non-inferior in AUC with respect to RACE. These newer, simpler scales may have acceptable diagnostic ability for LVO and be more easily adopted by EMS. Disclosures R. James: 1; C; Medtronic, Medtronic. A. Cruz: None. E. Fortuny: None. B. Ugiliweneza: None. D. Wang: None. A. White: None. N. Khattar: None. S. Adams: None. B. Gallinore: None. D. Ding: None. S. Wolfe: None. D. Heck: None.