Accuracy of Prehospital Stroke Scales Identified

Martijne Duvekot, MD

Results from prospective, observational cohort PRESTO study that aimed to validate 8 prehospital stroke scales found them all to detect large vessel occlusion in the anterior circulation (aLVO) with acceptable-to-good accuracy.¹

Among the prehospital stroke scales observed, the Rapid Arterial oCclusion Evaluation (RACE), Gaze-Face-Arm-Speech-Time (G-FAST), and Conveniently Grasped Field Assessment Stroke Triage (CG-FAST), were the best performing, and approached the performance of the clinician-assessed National Institutes of Health Stroke Scale (NIHSS).

Martijne Duvekot, MD, department of neurology, Albert Schweitzer Hospital, and colleagues collected data from paramedics who used mobile apps to assess items from 8 prehospital stroke scales: RACE, Los Angeles Motor Scale (LAMS), Cincinnati Stroke Triage Assessment Tool (C-STAT), G-FAST, Prehospital Acute Stroke Severity (PASS), Cincinnati Prehospital Stroke Scale (CPSS), CG-FAST, and the FAST-PLUS (Face-Arm-Speech-Time plus severe arm or leg motor deficit) test.

Prehospital stroke scale performance was expressed as the area under the receiver operating characteristic curve (AUC) and was compared with NIHSS scores assessed by clinicians at the emergency department.

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Of all the 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; 95% CI, 0.76–0.84), CG-FAST (0.80; 95% CI, 0.76–0.84), LAMS (0.79; 95% CI, 0.75–0.83), CPSS (0.79; 95% CI, 0.75–0.83), PASS (0.76; 0.72–0.80), C-STAT (0.75; 95% CI, 0.71–0.80), and FAST-PLUS (0.72; 95% CI, 0.67–0.76).

The investigators did note that future studies are needed to investigate whether the use of these scales in regional transportation strategies can optimize outcomes of patients with ischemic stroke. The use of NIHSS by clinicians within the emergency department did perform better than the prehospital stroke scales, indicated by an AUC of 0.86 (95% CI, 0.83–0.89).

Patients included in the study were at least 18 years of age and were transported by ambulance to 1 of the 8 hospitals observed. Researchers also included individuals with blood glucose of at least 2.5 mmol/L. Those who presented more than 6 hours after symptom onset were excluded from the analysis.

Another recent study from T. Truc My Nguyen, MD, et al. analyzed the accuracy of 7 prehospital scales in the assessment of those with acute stroke codes in an ambulance setting, which also found them all to have good accuracy, high specificity, and low sensitivity. Particularly, the Los Angeles Motor Scale (LAMS) and the Rapid Arterial Occlusion Evaluation (RACE) led the group in accuracy.²

In addition to LAMS and RACE, the study assessed the Cincinnati Stroke Triage Assessment Tool prediction (C-STAT), the Prehospital Acute Stroke Severity (PASS) scale, G-FAST, Field Assessment Stroke Triage for Emergency Destination (FAST-ED), and gaze, facial asymmetry, level of consciousness, extinction/inattention scales for symptomatic large anterior vessel occlusion (sLAVO). Accuracy of the scales ranged from 0.79 to 0.89, with LAMS (0.89; 95% CI, 0.87–0.90) and RACE (0.88; 95% CI, 0.86–0.89) scales yielding the highest scores. Sensitivity ranged from 38% to 62%, and specificity from 80% to 93%. Scale feasibility rates, which should be taken into account before implementing a scale, ranged from 78% to 88%, with the highest rate for the PASS scale (87.9%, 95% CI, 86.5–89.4).

Duvekot et al. noted in their work that the validation of the prehospital stroke scales will help alleviate the interhospital transfers, thus allowing patients to receive the full effect of the time-sensitive endovascular treatment (EVT) procedure.

Quick access to EVT centers for acute stroke has been limited in capacities, according to a study published in March 2020. The data suggested that EVT centers that are available within 15 minutes or less are only accessible for 20% of the population in the United States, pointing to a need for both national and state efforts to improve access to EVT.³

The findings revealed state-varied results, with enhanced access most increased by increasing EVT centers or bypassing non-EVT centers to the closest center, though bypass showed more potential for maximizing patients’ direct access to EVT.

All told, flipping the top 10% of non-EVT centers to EVT capable would increase direct access within 15 minutes to an additional 7.5% (n = 2,094,953) nationwide, while bypassing non-EVT centers would result in an improvement in coverage for 16.7% (n = 51,689,614).

Wolfgang G. Kunz, MD, associate professor of radiology, Ludwig-Maximilians-University of Munich, and the HERMES collaborators, also published research that showed late intervention with EVT can decrease the economic value of care. The investigators suggested that healthcare policies to implement efficient pre-hospital triage and accelerate in-hospital workflow may be needed after they found that any time delay to EVT reduced quality-adjusted life years (QALY) and decreased the economic value of care provided by this intervention.⁴

REFERENCES

1. Duvekot M, Venema E, Rozeman AD, et al. Comparison of eight prehospital stroke scales to detect intracranial large vessel occlusion in suspected stroke (PRESTO): a prospective observational study. Lancet Neurol. Published online January 7, 2021. doi: 10.106/S1474-4422(20)30439-7

2. Nguyen TTM, van den Wijngaard IR, Bosch J, et al. Comparison of prehospital scales for predicting large anterior vessel occlusion in the ambulance setting. JAMA Neurol. Published online November 20, 2020. doi:10.1001/jamaneurol.2020.4418

3. Sarraj A, Savitz S, Pujara D, et al. Endovascular Thrombectomy for Acute Ischemic Strokes: Current US Access Paradigms and Optimization Methodology. Stroke. Published online February 12, 2020. doi: 10.1161/STROKEAHA.120.028850

4. Kunz WG, Hunink MG, Almekhlafi MA, et al. Public health and cost consequences of time delays to thrombectomy for acute ischemic stroke. Neurology. Published online September 17, 2020. doi: 10.1212/WNL.0000000000010867