Prehospital Large-Vessel Occlusion Stroke Detection Scales: A Pooled Individual Patient Data Analysis of 2 Prospective Cohorts.

Background and objectives: Various prehospital scales have been developed to detect patients with anterior-circulation large-vessel occlusion (aLVO) ischemic stroke to enable direct transportation to a thrombectomy-capable stroke center. To guide implementation, a head-to-head comparison of aLVO stroke detection scales is needed to determine which scale is most useful for prehospital triage in different regional contexts. We aimed to systematically identify and compare these scales.

Methods: Published prehospital aLVO stroke scales were identified with a systematic literature search. Scales were reconstructed from individual patient data of 2 large prospective observational cohort studies conducted between 2018 and 2019, the Leiden Prehospital Stroke Study and PREhospital triage of patients with suspected STrOke symptoms study. Both studies included consecutive adult patients suspected by paramedics of having a stroke within 6 hours of symptom onset, from 4 Dutch ambulance regions, encompassing 15 stroke centers and serving 3.7 million people. All data used for the reconstruction of scales were acquired by paramedics in the field before hospital arrival. Scales' diagnostic performance to detect aLVO stroke was compared with the area under the receiver operating characteristic curve (AUROC) of the full scale and sensitivity and specificity at the scales' original cut-point. Decision curve analysis was used to evaluate harm-benefit trade-offs between delaying IV thrombolysis and expediting endovascular thrombectomy with direct transportation of patients to a thrombectomy-capable center.

Results: We identified 63 aLVO scales, of which 14 could be reconstructed. Of 2,358 included patients (mean age 70 years; 47% female), 231 (9.8%) had aLVO stroke. The AUROC was highest for Rapid Arterial oCclusion Evaluation (RACE) (0.81, 95% CI 0.78-0.84), Los Angeles Motor Scale (LAMS) (0.80, 95% CI 0.77-0.83), Gaze-Face-Arm-Speech-Time (G-FAST) (0.80, 95% CI 0.77-0.83), and modified Gaze-Face-Arm-Speech-Time (mG-FAST) (0.79, 95% CI 0.76-0.82). The Emergency Medical Stroke Assessment had highest sensitivity (85%, 95% CI 80%-90%) but lowest specificity (58%, 95% CI 56%-61%) while Cincinnati Prehospital Stroke Scale with an adjusted cut-point of 3 + gaze had highest specificity (94%, 95% CI 93%-95%) but lowest sensitivity (35%, 95% CI 29%-41%). In decision curve analysis, RACE had the highest benefit across a clinically reasonable range of harm-benefit trade-offs.

Discussion: RACE, LAMS, G-FAST, and mG-FAST are the best-performing scales, with RACE being preferred in most triage settings. Our findings may support policymakers with implementing a scale suitable for their region.