Prehospital Acute Stroke Severity Scale to Predict Large Artery Occlusion: Design and Comparison With Other Scales.
We designed and validated a simple prehospital stroke scale to identify emergent large vessel occlusion (ELVO) in patients with acute ischemic stroke and compared the scale to other published scales for prediction of ELVO.



A national historical test cohort of 3127 patients with information on intracranial vessel status (angiography) before reperfusion therapy was identified. National Institutes of Health Stroke Scale (NIHSS) items with the highest predictive value of occlusion of a large intracranial artery were identified, and the most optimal combination meeting predefined criteria to ensure usefulness in the prehospital phase was determined. The predictive performance of Prehospital Acute Stroke Severity (PASS) scale was compared with other published scales for ELVO.



The PASS scale was composed of 3 NIHSS scores: level of consciousness (month/age), gaze palsy/deviation, and arm weakness. In derivation of PASS 2/3 of the test cohort was used and showed accuracy (area under the curve) of 0.76 for detecting large arterial occlusion. Optimal cut point ≥2 abnormal scores showed: sensitivity=0.66 (95% CI, 0.62-0.69), specificity=0.83 (0.81-0.85), and area under the curve=0.74 (0.72-0.76). Validation on 1/3 of the test cohort showed similar performance. Patients with a large artery occlusion on angiography with PASS ≥2 had a median NIHSS score of 17 (interquartile range=6) as opposed to PASS <2 with a median NIHSS score of 6 (interquartile range=5). The PASS scale showed equal performance although more simple when compared with other scales predicting ELVO.



The PASS scale is simple and has promising accuracy for prediction of ELVO in the field.
From the Department of Neurology, Aarhus University Hospital, Aarhus, Denmark (S.H., D.D., G.A.); and Department of Clinical Epidemiology, Aarhus University, Aarhus, Denmark (S.H., S.P.J.). sidshast@rm.dk.
Sidsel
S
Hastrup
From the Department of Neurology, Aarhus University Hospital, Aarhus, Denmark (S.H., D.D., G.A.); and Department of Clinical Epidemiology, Aarhus University, Aarhus, Denmark (S.H., S.P.J.).
Dorte
D
Damgaard
From the Department of Neurology, Aarhus University Hospital, Aarhus, Denmark (S.H., D.D., G.A.); and Department of Clinical Epidemiology, Aarhus University, Aarhus, Denmark (S.H., S.P.J.).
Søren Paaske
SP
Johnsen
From the Department of Neurology, Aarhus University Hospital, Aarhus, Denmark (S.H., D.D., G.A.); and Department of Clinical Epidemiology, Aarhus University, Aarhus, Denmark (S.H., S.P.J.).
Grethe
G
Andersen
D000368:Aged; D000369:Aged, 80 and over; D001157:Arterial Occlusive Diseases / Q000175:diagnosis* / Q000000981:diagnostic imaging; D001921:Brain / Q000000981:diagnostic imaging*; D002545:Brain Ischemia / Q000175:diagnosis* / Q000000981:diagnostic imaging; D000072226:Computed Tomography Angiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D020521:Stroke / Q000175:diagnosis* / Q000000981:diagnostic imaging
Emergency Medical Services; cerebrovascular occlusion; scales; stroke; thrombectomy; triage