Prehospital Stroke Scales Outperform National Institutes of Health Stroke Scale in Predicting Large Vessel Occlusion in a Large Academic Telestroke Network

Background: With growing emphasis on prehospital identification of large vessel occlusion (LVO), some experts have advocated for prehospital involvement of vascular neurologists. Prehospital telestroke may improve triage and in-hospital treatment, but the accuracy of prehospital LVO scales in telestroke has not been investigated. Methods: We performed a retrospective study of telestroke consultations in a large academic telestroke network from 2019 to 2020. We assessed performance of 7 LVO scales using the NIHSS score at presentation (RACE, C-STAT, FAST-ED, 3I-SS, PASS, VAN, and G-FAST). We performed two analyses using different LVO definitions: (1) anterior LVO including occlusion of the internal carotid (ICA), middle cerebral (M1 or M2), or anterior cerebral (A1 or A2) arteries; and (2) any LVO including occlusion sites above plus basilar artery or posterior cerebral artery (P1 or P2). Diagnostic performance was assessed via sensitivity, specificity, negative predictive value, positive predictive value, positive likelihood ratio, negative likelihood ratio, and accuracy using established thresholds of each scale. These results were compared to NIHSS at thresholds of 6, 8, and 10. Area under curve (AUC) was calculated using c-statistics by treating scales as continuous variables. Results: A total of 625 patients were included; 111 (17.8%) patients had an anterior LVO, 118 (18.9%) patients had any LVO, and 182 (29.1%) patients had stroke mimic diagnosis. Mean age (SD) was 67.9 (15.9), 48.3% were female, and 93.4% were white. Mean NIHSS (SD) was 14.9 (8.4) for patients with anterior LVO, 4.7 (5.0) for patients with non-LVO ischemic stroke, and 4.4 (5.8) for stroke mimic (p<0.001). Compared to the NIHSS, FAST-ED and RACE scales demonstrated higher accuracy and AUC for LVO detection. Conclusions: Both the FAST-ED and RACE scales outperformed the NIHSS for LVO detection in patients evaluated by telestroke. These scales may be valid alternatives to the NIHSS examination in this setting. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement Funding was provided by the Mayo Clinic Arizona Neurology Department for biostatistical support. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: This study was reviewed and determined to be exempt by the Mayo Clinic Institutional Review Board. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes The data that support the findings of this study are available from the corresponding author upon reasonable request.