Background: Due to the time-sensitive effect of endovascular treatment (EVT), rapid prehospital identification of large vessel occlusion (LVO) in suspected stroke patients is essential to optimize outcome. Inter-hospital transfers are an important cause of delay of EVT. Prehospital stroke scales have been proposed to select patients with LVO for direct transport to an endovascular-capable intervention centre. We aimed to prospectively validate eight prehospital stroke scales in the field.
Methods: In a multi-centre prospective observational cohort study, we included suspected stroke patients transported by ambulance in the Southwest Netherlands. Paramedics assessed items from eight prehospital stroke scales: Rapid Arterial oCclusion Evaluation (RACE), Los Angeles Motor Scale (LAMS), Cincinnati Stroke Triage Assessment Tool (C-STAT), Gaze-Face-Arm-Speech-Time (G-FAST), Prehospital Acute Stroke Severity (PASS), Cincinnati Prehospital Stroke Scale (CPSS), Conveniently-Grasped Field Assessment Stroke Triage (CG-FAST), and the FAST PLUS Test. Patients that presented beyond six hours from symptom onset were excluded. Primary outcome was the clinical diagnosis of ischaemic stroke with a proximal intracranial LVO in the anterior circulation (aLVO) on CT-angiography. Prehospital stroke scale performance was expressed as the area under the receiver operating characteristic curve (AUC) and was compared with National Institute of Health Stroke Scale (NIHSS) scores assessed by physicians at the emergency department.
Findings: We included 1039 patients, of which 121 patients (12%) were diagnosed with aLVO. AUCs for the prehospital stroke scales ranged from 0·69 (FAST PLUS) to 0·82 (RACE). The performance of RACE was not significantly different from G-FAST (AUC=0·80, p=0·14) and CG-FAST (AUC=0·80, p=0·09), but was significantly different from the other scales (p-values<0·05). The NIHSS performed somewhat better (AUC 0·86, p-values<0·05).
Interpretation: Prehospital stroke scales detect aLVO with good accuracy and approach the performance of the physician-assessed NIHSS. RACE is the best performing prehospital stroke scale, but does not differ significantly from G-FAST and CG-FAST.
Trial Registration: This study was registered at the Netherlands Trial Register (www.trialregister.nl), NL7387
Funding: BeterKeten collaboration and Theia Foundation (Zilveren Kruis)
Declaration of Interests: Diederik Dippel and Aad van der Lugt report funding from the Dutch Heart Foundation, Brain Foundation Netherlands, The Netherlands Organisation for Health Research and Development, Health Holland Top Sector Life Sciences & Health, and unrestricted grants from Penumbra Inc., Stryker, Stryker European Operations BV, Medtronic, Thrombolytic Science, LLC and Cerenovus for research, all paid to institution. Pieter Jan van Doormaal reports funding from Stryker, paid to institution and an unrestricted fee from Bayer. All other authors declare no conflict of interest.
Ethics Approval Statement: This study was conducted in accordance with the Dutch Agreement on Medical Treatment Act and the European General Data Protection Regulation. The Institutional Review Board of the Erasmus MC University Medical Centre has reviewed the study protocol and confirmed that the Dutch Medical Research Involving Human Subjects Act is not applicable. Because our study met the exceptions of informed consent regulations, the need for informed consent was waived. Patients or their relatives were informed about the study and could withdraw from the study through an opt-out system.