Design and validation of a clinical scale for prehospital stroke recognition, severity grading and prediction of large vessel occlusion: the shortened NIH Stroke Scale for emergency medical services

• Published in: BMJ open 2017-09, Vol.7 (9), p.e016893-e016893
• Main Authors: Purrucker, Jan Christoph, Härtig, Florian, Richter, Hardy, Engelbrecht, Andreas, Hartmann, Johannes, Auer, Jonas, Hametner, Christian, Popp, Erik, Ringleb, Peter Arthur, Nagel, Simon, Poli, Sven
• Format: Article
• Language: English
• Subjects: Area Under Curve; Arterial Occlusive Diseases - complications; Arterial Occlusive Diseases - diagnosis; Brain Ischemia - complications; Brain Ischemia - diagnosis; Carotid arteries; Design; Emergency medical care; Emergency Medical Services; Emergency services; Female; Hospitals; Humans; Intensive care; Male; Mortality; Neurology; Predictive Value of Tests; Retrospective Studies; ROC Curve; Sensitivity and Specificity; Severity of Illness Index; Stroke; Stroke - diagnosis; Stroke - etiology; Triage; Veins & arteries
• ISSN: 2044-6055; 2044-6055
• DOI: 10.1136/bmjopen-2017-016893

ObjectiveTo develop an NIH Stroke Scale (NIHSS)-compatible, all-in-one scale for rapid and comprehensive prehospital stroke assessment including stroke recognition, severity grading and progression monitoring as well as prediction of large vessel occlusion (LVO).MethodsEmergency medical services (EMS) personnel and stroke physicians (n=326) rated each item of the NIHSS regarding suitability for prehospital use; best rated items were included. Stroke recognition was evaluated retrospectively in 689 consecutive patients with acute stroke or stroke mimics, prediction of LVO in 741 consecutive patients with ischaemic stroke with acute vessel imaging independent of admission NIHSS score.ResultsNine of the NIHSS items were rated as ‘suitable for prehospital use.’ After excluding two items in order to increase specificity, the final scale (termed shortened NIHSS for EMS, sNIHSS-EMS) consists of ‘level of consciousness’, ‘facial palsy’, ‘motor arm/leg’, ‘sensory’, ‘language’ and ‘dysarthria’. Sensitivity for stroke recognition of the sNIHSS-EMS is 91% (95% CI 86 to 94), specificity 52% (95% CI 47 to 56). Receiver operating curve analysis revealed an optimal cut-off point for LVO prediction of ≥6 (sensitivity 70% (95% CI 65 to 76), specificity 81% (95% CI 76 to 84), positive predictive value 70 (95% CI 65 to 75), area under the curve 0.81 (95% CI 0.78 to 0.84)). Test characteristics were non-inferior to non-comprehensive scales.ConclusionsThe sNIHSS-EMS may overcome the sequential use of multiple emergency stroke scales by permitting parallel stroke recognition, severity grading and LVO prediction. Full NIHSS-item compatibility allows for evaluation of stroke progression starting at the prehospital phase.