Derivation and Validation of the Emergency Medical Stroke Assessment and Comparison of Large Vessel Occlusion Scales Toby I. Gropen, MD,* Amelia Boehme, PhD,† , ‡ Sheryl Martin-Schild, MD,§ Karen Albright, DO, MPH,‖ , ¶ Alyana Samai, PhD,# Sammy Pishanidar, MD,** , †† Nazli Janjua, MD,‡‡ Ethan S. Brandler, MD,§§ and Steven R. Levine, MD‖‖ , ¶¶ Background: This study aims to develop a simple scale to identify patients with prehospital stroke with large vessel occlusion (LVO), without losing sensitivity for other stroke types. Methods: The Emergency Medical Stroke Assessment (EMSA) was derived from the National Institutes of Health Stroke Scale (NIHSS) items and validated for prediction of LVO in a separate cohort. We compared the EMSA with the 3-item stroke scale (3I-SS), Cincinnati Prehospital Stroke Severity Scale (C-STAT), Rapid Arterial oCclusion Evaluation (RACE) scale, and Field Assess- ment Stroke Triage for Emergency Destination (FAST-ED) for prediction of LVO and stroke. We surveyed paramedics to assess ease of use and interpretation of scales. Results: The combination of gaze preference, facial asymmetry, asymmetri- cal arm and leg drift, and abnormal speech or language yielded the EMSA. An EMSA greater than or equal to 3, 75% sensitivity, and 50% specificity signifi- cantly reduced the likelihood of LVO (LR- = .489, 95% confidence interval .366- 0.637) versus 3I-SS less than 4 (.866, .798-0.926). An EMSA greater than or equal to 1, 93% sensitivity, and 47% specificity significantly reduced the likelihood of stroke (LR- = .142, .068-0.299) versus 3I-SS (.476, .330-0.688) and C-STAT (.858, .717- 1.028). EMSA was rated easy to perform by 72% (13 of 18) of paramedics versus 67% (12 of 18) for FAST-ED and 6% (1 of 18) for RACE (χ 2 = 27.25, P < .0001), and easy to interpret by 94% (17 of 18) versus 56% (10 of 18) for FAST-ED and 11% (2 of 18) for RACE (χ 2 = 21.13, P < .0001). Conclusions: The EMSA has From the *Department of Neurology, University of Alabama at Birmingham, Birmingham, Alabama; †Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, NY; ‡Department of Neurology, Columbia University Medical Center, New York, NY; §Departments of Neurology & Stroke, New Orleans East Hospital and Touro Infirmary, New Orleans, Louisiana; ‖Department of Neu- rology, School of Medicine; ¶Department of Epidemiology, School of Public Health, University of Alabama at Birmingham, Birmingham, Alabama; #Department of Neurology, Tulane University, New Orleans, Louisiana; **Department of Neurology, New York-Presbyterian Queens, Flush- ing, New York; ††Department of Neurology, Weill Cornell Medical College, New York, New York; ‡‡Asia Pacific Comprehensive Stroke Institute, Pomona, California; §§Department of Emergency Medicine, Stony Brook University School of Medicine, State University of New York, Stony Brook, New York; ‖‖Departments of Neurology and Emergency Medicine, State University of New York Downstate Medical Center, Brook- lyn, New York; and ¶¶Departments of Neurology and Emergency Medicine, Kings County Hospital Center, Brooklyn, New York. Received November 3, 2016; revision received October 1, 2017; accepted October 16, 2017. Grant support: T.I.G. was supported by the University of Alabama at Birmingham Health Services Foundation General Endowment Fund grant “Refinement of the Prehospital Stroke System.” S.R.L. was supported by NIH-NINDS grants U10NS077378 and U10NS080377. This work was performed at Departments of Neurology, SUNY Downstate Long Island College Hospital, Brooklyn, NY; Tulane University, New Orleans, LA; and University of Alabama at Birmingham, AL. Author contributions: Toby I. Gropen, Amelia Boehme, Sheryl Martin-Schild, Karen Albright: Study design, data collection and analysis, and writing. Alyana Samai: Study design, data collection, and analysis. Sammy Pishanidar: Study design, data collection. Nazli Janjua: Study design, data collection. Ethan S. Brandler: Study design, data collection and analysis, and writing. Steven R. Levine: Study design, data col- lection and analysis, and writing. Address correspondence to Toby I. Gropen, MD, FAHA, Division of Cerebrovascular Disease, The University of Alabama at Birmingham, RWUH M226, 619 19th St S, Birmingham, AL 35249-3280. E-mail: tgropen@uabmc.edu. 1052-3057/$ - see front matter © 2017 National Stroke Association. Published by Elsevier Inc. All rights reserved. https://doi.org/10.1016/j.jstrokecerebrovasdis.2017.10.018 ARTICLE IN PRESS Journal of Stroke and Cerebrovascular Diseases, Vol. ■■, No. ■■ (■■), 2017: pp ■■–■■ 1