Evaluation of a new large vessel occlusion scale based on a prospective registry study.

BACKGROUND AND PURPOSE: Prehospital assessment is important for transporting patients with large vessel occlusion (LVO) to hospitals that are capable of intravenous thrombolysis and/or mechanical thrombectomy. Although its simplicity and accuracy are difficult to reconcile, we aimed to create an accurate prehospital scale that can be easily used by emergency services.

METHODS

Patients who were transported with suspected stroke to six stroke centers within 24 hours of onset were evaluated in the field by emergency services and then again immediately after hospital arrival. The following items were assessed: (1) atrial fibrillation, (2) conjugate eye deviation, (3), unilateral spatial neglect, (4) aphasia, (5) dysarthria, (6) facial weakness, and (7) upper extremity weakness. Logistic regression was used to estimate the weighting coefficients for the scales. The scale was also evaluated by occluded vessel (ICA, M1, M2, BA).

RESULTS

The estimated coefficients of dysarthria in the full logistic model were nearly equal to zero. Accuracy was almost equal between the simple model (dysarthria was excluded) and full logistic model. The scale as assessed by emergency services showed slightly lower accuracy than by medical institution. When evaluated by emergency services, positive predictive value was >50% for 3 points; negative predictive value was 90% for 2 points. By occluded vessel, the area under the curve of our scale for ICA, M1, and M2 occlusions was approximately 0.7 or higher.

CONCLUSIONS

Our prehospital scale with 1 point each for atrial fibrillation, conjugate eye deviation, unilateral spatial neglect, aphasia, facial weakness, and upper extremity weakness was useful for screening LVO, especially ICA, M1, and M2 occlusion.