Elsevier

The Lancet Neurology

Volume 20, Issue 3, March 2021, Pages 213-221
The Lancet Neurology

Articles
Comparison of eight prehospital stroke scales to detect intracranial large-vessel occlusion in suspected stroke (PRESTO): a prospective observational study

https://doi.org/10.1016/S1474-4422(20)30439-7Get rights and content

Summary

Background

Due to the time-sensitive effect of endovascular treatment, rapid prehospital identification of large-vessel occlusion in individuals with suspected stroke is essential to optimise outcome. Interhospital transfers are an important cause of delay of endovascular treatment. Prehospital stroke scales have been proposed to select patients with large-vessel occlusion for direct transport to an endovascular-capable intervention centre. We aimed to prospectively validate eight prehospital stroke scales in the field.

Methods

We did a multicentre, prospective, observational cohort study of adults with suspected stroke (aged ≥18 years) who were transported by ambulance to one of eight hospitals in southwest Netherlands. Suspected stroke was defined by a positive Face-Arm-Speech-Time (FAST) test. We included individuals with blood glucose of at least 2·5 mmol/L. People who presented more than 6 h after symptom onset were excluded from the analysis. After structured training, paramedics used a mobile app to assess 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 (Face-Arm-Speech-Time plus severe arm or leg motor deficit) test. The primary outcome was the clinical diagnosis of ischaemic stroke with a proximal intracranial large-vessel occlusion in the anterior circulation (aLVO) on CT angiography. Baseline neuroimaging was centrally assessed by neuroradiologists to validate the true occlusion status. Prehospital stroke scale performance was expressed as the area under the receiver operating characteristic curve (AUC) and was compared with National Institutes of Health Stroke Scale (NIHSS) scores assessed by clinicians at the emergency department. This study was registered at the Netherlands Trial Register, NL7387.

Findings

Between Aug 13, 2018, and Sept 2, 2019, 1039 people (median age 72 years [IQR 61–81]) with suspected stroke were identified by paramedics, of whom 120 (12%) were diagnosed with aLVO. Of all prehospital stroke scales, the AUC for RACE was highest (0·83, 95% CI 0·79–0·86), followed by the AUC for G-FAST (0·80, 0·76–0·84), CG-FAST (0·80, 0·76–0·84), LAMS (0·79, 0·75–0·83), CPSS (0·79, 0·75–0·83), PASS (0·76, 0·72–0·80), C-STAT (0·75, 0·71–0·80), and FAST-PLUS (0·72, 0·67–0·76). The NIHSS as assessed by a clinician in the emergency department did somewhat better than the prehospital stroke scales with an AUC of 0·86 (95% CI 0·83–0·89).

Interpretation

Prehospital stroke scales detect aLVO with acceptable-to-good accuracy. RACE, G-FAST, and CG-FAST are the best performing prehospital stroke scales out of the eight scales tested and approach the performance of the clinician-assessed NIHSS. Further studies are needed to investigate whether use of these scales in regional transportation strategies can optimise outcomes of patients with ischaemic stroke.

Funding

BeterKeten Collaboration and Theia Foundation (Zilveren Kruis).

Introduction

Worldwide, stroke is one of the leading causes of death or disability, particularly in individuals with ischaemic stroke caused by a proximal intracranial large-vessel occlusion.1 Both intravenous thrombolysis and endovascular thrombectomy have been proven effective in patients with ischaemic stroke, but their effect is highly time-dependent.2, 3 In people with ischaemic stroke due to large-vessel occlusion, intravenous thrombolysis is less effective and endovascular thrombectomy is generally indicated.4 In current clinical practice, individuals with suspected stroke are usually transported to the nearest hospital for rapid intravenous thrombolysis. People who are eligible for endovascular thrombectomy are subsequently transferred to a specialised intervention centre. Despite optimisation of prehospital and in-hospital workflow, interhospital transfers remain an important cause of delay in endovascular thrombectomy and are associated with worse outcomes for patients, compared with those who have endovascular thrombectomy who do not require transfer.5, 6, 7 Prehospital triage to identify people eligible for endovascular thrombectomy at an early stage could prevent unnecessary interhospital transfers and optimise clinical outcomes of individuals with ischaemic stroke due to large-vessel occlusion. Prehospital stroke scales can be used to detect people with a high likelihood of having a large-vessel occlusion and could guide who should be transported directly to an intervention centre.8

Research in context

Evidence before this study

We searched PubMed with no language restrictions for papers published from database inception up to July 6, 2020, to include prehospital prospective validation studies of prehospital stroke scales. We used the search terms “prehospital triage”, “prehospital stroke scale”, “large vessel occlusion”, and “mechanical thrombectomy” or “endovascular therapy”, and we cross-checked references of eligible papers. Many prehospital stroke scales have been developed, but prospective prehospital validation studies are scarce. We identified nine studies validating prehospital stroke scales in the field. None of these studies validated multiple scales simultaneously and most were done in small or selected populations, limiting the generalisability of their results.

Added value of this study

To the best of our knowledge, our study is the first to validate eight prehospital stroke scales simultaneously in a large population of individuals with suspected stroke by paramedics in the field using a mobile app. Our study provided reliable estimates of the in-field performance of eight prehospital stroke scales. CT angiographies were done in hospital and reassessed by an Imaging Core Laboratory committee to validate the true occlusion status.

Implications of all the available evidence

Prehospital stroke scales are helpful to guide prehospital selection of people with suspected stroke. In general, prehospital stroke scales detect large-vessel occlusions well and the different scales perform similarly. The best in our study were Rapid Arterial oCclusion Evaluation (RACE), Gaze-Face-Arm-Speech-Time (G-FAST), and Conveniently-Grasped Field Assessment Stroke Triage (CG-FAST), which approached the performance of the clinician-assessed National Institutes of Health Stroke Scale (NIHSS). However, due to its complexity, NIHSS is not the ideal scale for assessment by paramedics in the field. Our finding that a field-assessed RACE score of 5 or higher corresponds to a 40% or higher risk of large-vessel occlusion in the anterior circulation (positive predictive value 0·40) supports implementation of RACE (or another prehospital stroke scale with a similar threshold) in clinical practice in most urban and suburban regions. However, in rural areas with longer driving times to the intervention centre, higher positive predictive value thresholds should be considered. With our study evidence, health-care professionals and policy makers might be able to better decide on the most suitable prehospital stroke scale and threshold to customise prehospital triage to regional characteristics, such as distribution of hospitals and their stroke treatment capabilities, population density, and regional workflow times.

Prehospital stroke scales are designed as short and simple clinical methods for assessment of patients by paramedics in the field. Most scales are derived from the National Institutes of Health Stroke Scale (NIHSS).8 Many scales have been published, and some have already been implemented as triage tools.9 However, prospective prehospital studies validating these scales are scarce, and performance of prehospital stroke scales has not been directly compared.9, 10, 11, 12, 13, 14, 15, 16 In the prehospital triage of patients with suspected stroke (PRESTO) study, we aimed to prospectively validate and compare eight prehospital stroke scales to assess their accuracy in estimating the likelihood of an intracranial large-vessel occlusion in people with suspected stroke in the prehospital setting.

Section snippets

Study design and patients

PRESTO was a multicentre, prospective, observational cohort study in southwest Netherlands, an area with approximately two million inhabitants. Eight different hospitals are located in the study region, and two centres are capable of endovascular thrombectomy. Individuals with symptoms of suspected stroke were recruited in the ambulance by paramedics from two ambulance services operating in the study region: Rotterdam-Rijnmond and Zuid-Holland Zuid. All participating hospitals and ambulance

Results

Between Aug 13, 2018, and Sept 2, 2019, 1334 patients were enrolled to the study while in an ambulance on the way to hospital. 20 patients were excluded because of an incorrect input of the (pseudonymised) identification number into the mobile app or because the patient was transferred to a hospital outside the study region or was referred to their family doctor (figure 1). We excluded a further 274 patients from the analysis because they presented more than 6 h after symptom onset, and one

Discussion

We did an in-field validation study of eight prehospital stroke scales to detect aLVO in a population of people with suspected stroke. Baseline neuroimaging was centrally assessed by skilled neuroradiologists to validate the true occlusion status. In general, performance of prehospital stroke scales in the field was acceptable to good. RACE, G-FAST, and CG-FAST had the highest AUCs and approached the AUC of the NIHSS as assessed by the clinician in the emergency department.

RACE, G-FAST, and

Data sharing

In compliance with the General Data Protection Regulation (GDPR), individual participant data are not available for other researchers. Because an opt-out system was used under strict conditions and patients were not informed about the possibility of sharing their data outside the PRESTO collaboration (appendix p 21), data sharing would be a violation of the GDPR. Information about analytical methods (eg, the data dictionary and the final R script [Oct 30, 2020]) for the statistical analysis,

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    PRESTO investigators are listed in the appendix

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