Abstract WP438: The Los Angeles Motor Scale (LAMS) is a Validated and Robust Tool for Paramedic Assessment of Stroke Severity in the Field

Abstract

Introduction: A simple, validated paramedic assessment of prehospital stroke severity would permit selective routing of more severe patients to Comprehensive Stroke Centers and a critical pretreatment deficit score in RCTs of prehospital intervention. The Los Angeles Motor Scale is a 3-item, 0-10 point motor stroke deficit scale developed for prehospital and ED use. Hypothesis: We assessed the hypothesis that the LAMS could be a valid tool for assessment of stroke severity on hospital arrival (HA) and prediction of 90D functional outcome. Methods: Among consecutive patients in the multi-ambulance, multi-hospital FAST-MAG trial, we assessed the predictive validity, concurrent, and divergent validity of the LAMS. Results: Among all 1,632 acute cerebrovascular disease patients in FAST-MAG, time from last known well (LKW) to prehospital LAMS exam was 30 mins (IQR 20 to 50), and from LKW to HA exam 147 mins (119-180). Median prehospital LAMS score was 4 (IQR 3 to 5). Concurrently performed HA LAMS and HA NIHSS correlated strongly, r=0.85, HA LAMS and GCS less so, r=0.62, as expected. Predictive validity of the prehospital LAMS was excellent. LAMS scores were higher in patients with dependency or death (mRS 0-3) at 90D, 4.2 vs 3.4, p <0.0001, and in patients with death by 90D, 4.3 vs 3.7, p<0.0001. The HA LAMS correlated with 90D mRS nearly as well as the concurrent HA NIHSS, r=0.55 vs 0.62. Each step on the LAMS scale was associated with a substantial shift to a worse distribution (Figure). Conclusion: The LAMS scale is a valid measure for paramedic use, permitting rapid quantification of prehospital stroke severity and predicting functional outcomes with accuracy comparable to the full NIH Stroke Scale.