Comparison of large vessel occlusion scales using prehospital patient reports

Prehospital identification of large vessel occlusion (LVO) holds significant potential to decrease the onset-to-treatment time. Several prehospital scales have been developed to identify LVO but data on their comparison has been limited. The aim of this study was to review the currently available prehospital LVO scales and compare their performance using prehospital data.

All patients transported by ambulance using stroke code on a six-month period were enrolled into the study. The prehospital patient reports were retrospectively evaluated by two investigators using sixteen LVO scales identified by literature search and expert opinion. After the evaluation, the computed tomography angiography results were reviewed by a neuroradiologist to confirm or exclude LVO.

Sixteen different LVO scales met the predetermined study criteria and were selected for further comparison. Using them, a total of 610 evaluations were registered. The sensitivity of the scales varied between 8%-73%, specificity between 71%-97% and overall accuracy between 71%-87%. The areas under curve (AUC) varied between 0.61-0.80 for the whole scale range and 0.53%-0.74 for the scales' binary cut-offs. The Field Assessment Stroke Triage for Emergency Destination (FAST-ED) was the only scale with AUC > 0.8. Regarding scales' binary cut-offs, The FAST-ED (0.70), Gaze - Face Arm Speech Time (G-FAST) (0.74) and Emergency Medical Stroke Assessment (EMSA) (0.72) were the only scales with AUC > 0.7.

In a comparison of 16 different LVO scales, the FAST-ED, G-FAST and EMSA achieved the highest overall performance.