Abstract WP277: The Los Angeles Motor Scale is an Effective Tool for Triaging Patients in the Prehospital Setting

Abstract

Introduction: The Los Angeles Motor Scale (LAMS) is a 3-item scale to identify motor deficits. This can identify severe strokes in the field so that patients can be transported appropriately. Methods: Prospective observational cohort study based in a county EMS system. Patients transported for stroke had a LAMS administered in the field. Outcome data from individual receiving hospitals collected within 45 days of the event. Results: Our cohort (n=2374) had a median age of 72 and was 51% female. 19% had LAMS 0, 14% LAMS 1, 13% LAMS 2, 17% LAMS 3, 16% LAMS 4, and 21% had LAMS 5. We generated three receiver operating characteristic curves for the interventions of mechanical intervention, tPA, and CTA perfusion imaging, with C statistics of .706, .632, and .668 respectively. All three models were significant using the likelihood ratio test, p < .0001. In all three models, the cut point was a LAMS of 4. Accordingly, a high LAMS was defined as 4 or 5, whereas a low LAMS was defined as <4. In the following table, all associations were significant with p < .0001 using the likelihood ratio test. The median NIHSS at hospital arrival was 6, IQR 2-13. For low LAMS it was 4 (IQR 1-8), and for high LAMS it was significantly greater at 13, IQR 7-21, p <.0001 using Wilcoxon’s rank-sum test. At hospital discharge, median NIHSS was 2, IQR 0-7. For low LAMS it was 1 (IQR 0-5), for high LAMS it was significantly greater at 5 (IQR 1-14.75), p < .0001 using Wilcoxon’s rank-sum test. Median NIHSS improvement was 2 points, p < .0001 (Wilcoxon signed-rank test). The differences were significant with p < .0001 for both low LAMS and high LAMS patients individually (Wilcoxon signed-rank test). Low LAMS patients had a median improvement of 1.5 points. High LAMS patients had a significantly greater median improvement of 4 points (p < .0001 using Wilcoxon rank-sum test), likely because they generally started out in worse condition. Conclusion: The LAMS is a powerful prehospital predictor of intervention and outcomes after acute stroke.