Prehospital Identification of Patients With Stroke—mNIHSS Versus FAST

Abstract

Introduction: Early identification of stroke is important. The Face Arm Speech Test (FAST) and the modified National Institutes of Health Stroke Scale (mNIHSS) are two tools for stroke identification.

Aim: The aims of this study are to investigate (a) whether the use of the mNIHSS in an emergency medical service (EMS) setting improves stroke/transient ischaemic attack (TIA) identification compared with the FAST, (b) to what extent “code stroke” is activated, and (c) which neurologic deficits/symptoms affect stroke identification.

Methods: The method used is a retrospective pre–post-implementation study. EMS stroke identification was examined before and after the introduction of the mNIHSS, replacing the FAST, for EMS stroke screening. The FAST was replaced with the mNIHSS on 1 December 2022. Patients ≥ 18 years of age, diagnosed with stroke/TIA from 1 January 2021 to 31 May 2023 and under the care of the EMS, not more than 72 h before hospital care, were included. Data was manually extracted from EMS medical records regarding whether the FAST or mNIHSS was performed and if stroke/TIA was identified by the EMS personnel. The association between the applied stroke screening tool and EMS identification of stroke/TIA was then studied.

Results: A total of 1849 EMS missions with a hospital-confirmed diagnosis of stroke/TIA were included. The most common diagnosis was ischaemic stroke, 59.4%. Haemorrhagic stroke constituted 10.8%, and TIA 29.8%. Stroke/TIA was identified in 82.5% of cases. When the mNIHSS was used for stroke assessment, stroke/TIA was identified in 87.6% of cases. The corresponding figure for the FAST was 88.4%. For patients in whom neurological symptoms were unassessed, or a method for assessment other than the mNIHSS/FAST was applied, the identification rate for stroke/TIA was 41.6%. When a physician was consulted, “code stroke” was activated in 58.6% of all cases. The corresponding figure for the mNIHSS was 57.2% and for the FAST 59.9%.

Conclusions: The stroke identification rate does not appear to differ between the FAST and mNIHSS. The FAST and mNIHSS result in “code stroke” activation to an equal extent. Speech impairment and arm or leg paresis appear to improve EMS stroke identification. Conversely, impaired balance, convulsions, and vertigo/dizziness are associated with a lower identification rate. Both initial EMS suspicion of stroke and the subsequent application of a stroke scale appear to facilitate stroke identification.