Abstract 104: The Field Assessment Stroke Triage for Emergency Destination (FAST-ED): a Simple and Accurate Pre-hospital Scale to Detect Large Vessel Occlusion Strokes

Abstract

Background: Intravenous tPA has a limited efficacy in large vessel occlusion strokes (LVOS). Thus LVOS patients may be better served by direct transfer to endovascular capable centers. We aimed to develop a field scale to identify LVOS. Methods: The FAST-ED scale was designed based on items of the NIHSS with higher predictive value for LVOS: Facial Palsy (scored 0-1), Arm Weakness (0-2), Speech Changes (0-2), Eye Deviation (0-2), and Denial/Neglect (0-2). The scale was tested in the STOPStroke cohort, a prospective study of patients who underwent CT angiography (CTA) within the first 24 hours of stroke onset. LVOS were defined by total occlusions involving the ICA-T, MCA-M1, MCA-2, or basilar arteries. Patients with partial, bi-hemispheric, and/or anterior + posterior circulation occlusions were excluded. Receiver operating characteristic (ROC) curve, sensitivity, specificity, positive (PPV) and negative predictive values (NPV) of FAST-ED were compared with the Rapid Arterial oCclusion Evaluation (RACE) scale and Cincinnati Prehospital Stroke Severity Scale (CPSSS). Results: LVO was detected in 240 out of the 727 qualifying patients (33%). FAST-ED had a strong correlation with NIHSS (r=0.92; P<0.001). FAST-ED had comparable accuracy to predict LVO to the more complex NIHSS and higher accuracy than RACE and CPSS (area under the ROC curve: 0.81, 0.80, 0.77 and 0.75 respectively). Better performance of FAST-ED could be shown at two distinct thresholds depending on the desired sensitivity/specificity trade-offs with scores ≥3 and ≥4 having sensitivity for LVO of 0.71 and 0.60, specificity 0.78 and 0.89, PPV 0.62 and 0.72, and NPV 0.84 and 0.82 versus RACE ≥5 of 0.55, 0.87, 0.68, 0.79 and CPSS ≥2 of 0.56, 0.85, 0.65, 0.78, respectively. Conclusions: FAST-ED is a simpler field scale that can be used by medical emergency professionals to accurately identify LVOS in the pre-hospital setting enabling rapid triage of patients to primary vs. endovascular capable stroke centers.

Streamlining Acute Stroke Care by Introducing National Institutes of Health Stroke Scale in the Emergency Medical Services: A Prospective Cohort Study

“…The prehospital NIHSS scoring was performed mean (SD) 42 ( 14) minutes earlier than the in-hospital scoring. Prehospital time was not significantly increased in the NIHSS-trained paramedic group compared with conventional paramedics (median [interquartile range] on-scene-time 18 [13][14][15][16][17][18][19][20][21][22][23][24][25] minutes versus 16 [11-23] minutes, P=0.064 and onset-to-hospital time 86 [65-128] minutes versus 84 [56-140] minutes, P=0.535).…”

Portable Neuromonitoring Device Detects Large Vessel Occlusion in Suspected Acute Ischemic Stroke

“…The dichotomous threshold for high probability LVO was selected based on prior literature (NIHSS score ≥6 and ≥10, Rapid Arterial Occlusion Evaluation ≥5, Field Assessment Stroke Triage for Emergency Destination ≥4, Cincinnati Stroke Assessment Tool ≥2, Los Angeles Motor Score ≥4). 2,[6][7][8][9] The PLD measured electrode cap placement time. Users rated hardware, software, cap placement, cap alignment, and electrode usability on a 1 to 5 scale (very easy, easy, moderate, difficult, very difficult).…”

“…The Rapid Arterial Occlusion Evaluation, Field Assessment Stroke Triage for Emergency Destination, Cincinnati Stroke Assessment Tool, and Los Angeles Motor Score were derived from the NIHSS using methods previously published. [6][7][8][9] Research personnel assessed grip strength. The dichotomous threshold for high probability LVO was selected based on prior literature (NIHSS score ≥6 and ≥10, Rapid Arterial Occlusion Evaluation ≥5, Field Assessment Stroke Triage for Emergency Destination ≥4, Cincinnati Stroke Assessment Tool ≥2, Los Angeles Motor Score ≥4).…”

Prehospital Triage Accuracy in Patients With Stroke Symptoms Assessed Within 6 to 24 Hours or With an Unknown Time of Onset

“…The Rapid Arterial Occlusion Evaluation scale was designed and initially validated on patients seen within 6 hours, subsequently revalidated within 8 hours. 7,8 Although several studies exist of prehospital LVO scales for assessment within up to 24 hours, [9][10][11] we have been unable to find publications comparing the performance of such scales across time strata since onset, for example, 0 to 6 versus 6 to 24 hours. Such comparisons may be relevant since optimal NIHSS cutoff values for LVO prediction decrease over time, 12 and, as evident from our results, the proportions of patients with transient ischemic attack and stroke mimics may differ between the 0 to 6 and 6 to 24 hour time periods.…”