title: Large Vessel Occlusion Scales Increase Delivery to Endovascular Centers Without Excessive Harm From Misclassifications.
abstract: Clinical large vessel occlusion (LVO) triage scales were developed to identify and bypass LVO to endovascular centers. However, there are concerns that scale misclassification of patients may cause excessive harm. We studied the settings where misclassifications were likely to occur and the consequences of these misclassifications in a representative stroke population.
  
  
  
  Prospective data were collected from consecutive ambulance-initiated stroke alerts at 2 stroke centers, with patients stratified into typical (LVO with predefined severe syndrome and non-LVO without) or atypical presentations (opposite situations). Five scales (Rapid Arterial Occlusion Evaluation [RACE], Los Angeles Motor Scale [LAMS], Field Assessment Stroke Triage for Emergency Destination [FAST-ED], Prehospital Acute Stroke Severity scale [PASS], and Cincinnati Prehospital Stroke Severity Scale [CPSSS]) were derived from the baseline National Institutes of Health Stroke Scale scored by doctors and analyzed for diagnostic performance compared with imaging.
  
  
  
  Of a total of 565 patients, atypical presentations occurred in 31 LVO (38% of LVO) and 50 non-LVO cases (10%). Most scales correctly identified >95% of typical presentations but <20% of atypical presentations. Misclassification attributable to atypical presentations would have resulted in 4 M1/internal carotid artery occlusions, with National Institutes of Health Stroke Scale score ≥6 (5% of LVO) being missed and 9 non-LVO infarcts (5%) bypassing the nearest thrombolysis center.
  
  
  
  Atypical presentations accounted for the bulk of scale misclassifications, but the majority of these misclassifications were not detrimental, and use of LVO scales would significantly increase timely delivery to endovascular centers, with only a small proportion of non-LVO infarcts bypassing the nearest thrombolysis center. Our findings, however, would require paramedics to score as accurately as doctors, and this translation is made difficult by weaknesses in current scales that need to be addressed before widespread adoption.
authors.affiliation: From the Department of Medicine and Neurology, Royal Melbourne Hospital (H.Z., L.P., S.M.D., B.C.V.C.), and The Florey Institute of Neuroscience and Mental Health (L.C.), University of Melbourne, Parkville, Australia; and Eastern Health Clinical School, Eastern Health, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Australia (S.C., H.M.D.). zhaohdr@live.com.
authors.forename: Henry
authors.initials: H
authors.lastname: Zhao
authors.affiliation: From the Department of Medicine and Neurology, Royal Melbourne Hospital (H.Z., L.P., S.M.D., B.C.V.C.), and The Florey Institute of Neuroscience and Mental Health (L.C.), University of Melbourne, Parkville, Australia; and Eastern Health Clinical School, Eastern Health, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Australia (S.C., H.M.D.).
authors.forename: Skye
authors.initials: S
authors.lastname: Coote
authors.affiliation: From the Department of Medicine and Neurology, Royal Melbourne Hospital (H.Z., L.P., S.M.D., B.C.V.C.), and The Florey Institute of Neuroscience and Mental Health (L.C.), University of Melbourne, Parkville, Australia; and Eastern Health Clinical School, Eastern Health, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Australia (S.C., H.M.D.).
authors.forename: Lauren
authors.initials: L
authors.lastname: Pesavento
authors.affiliation: From the Department of Medicine and Neurology, Royal Melbourne Hospital (H.Z., L.P., S.M.D., B.C.V.C.), and The Florey Institute of Neuroscience and Mental Health (L.C.), University of Melbourne, Parkville, Australia; and Eastern Health Clinical School, Eastern Health, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Australia (S.C., H.M.D.).
authors.forename: Leonid
authors.initials: L
authors.lastname: Churilov
authors.affiliation: From the Department of Medicine and Neurology, Royal Melbourne Hospital (H.Z., L.P., S.M.D., B.C.V.C.), and The Florey Institute of Neuroscience and Mental Health (L.C.), University of Melbourne, Parkville, Australia; and Eastern Health Clinical School, Eastern Health, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Australia (S.C., H.M.D.).
authors.forename: Helen M
authors.initials: HM
authors.lastname: Dewey
authors.affiliation: From the Department of Medicine and Neurology, Royal Melbourne Hospital (H.Z., L.P., S.M.D., B.C.V.C.), and The Florey Institute of Neuroscience and Mental Health (L.C.), University of Melbourne, Parkville, Australia; and Eastern Health Clinical School, Eastern Health, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Australia (S.C., H.M.D.).
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Davis
authors.affiliation: From the Department of Medicine and Neurology, Royal Melbourne Hospital (H.Z., L.P., S.M.D., B.C.V.C.), and The Florey Institute of Neuroscience and Mental Health (L.C.), University of Melbourne, Parkville, Australia; and Eastern Health Clinical School, Eastern Health, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Australia (S.C., H.M.D.).
authors.forename: Bruce C V
authors.initials: BC
authors.lastname: Campbell
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001157:Arterial Occlusive Diseases / Q000175:diagnosis*; D002545:Brain Ischemia / Q000175:diagnosis*; D004636:Emergency Service, Hospital; D005260:Female; D006782:Hospitals, Special; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D020521:Stroke / Q000175:diagnosis*; D014187:Transportation of Patients / Q000592:standards* / Q000706:statistics & numerical data; D014218:Triage / Q000379:methods* / Q000592:standards / Q000706:statistics & numerical data; D055815:Young Adult
keywords: ambulance diversion; diagnosis; endovascular thrombectomy; large vessel occlusion; stroke; triage