Prehospital Stroke Detection in Women Is More Than Identifying LVOs

Optimal prehospital management with rapid identification of stroke suspects is crucial for rapid access to hyperacute stroke therapies and strongly influences clinical outcomes and mortality.¹

Prehospital emergency medical service personnel only have limited diagnostic equipment to conclude the most time-sensitive diagnosis of an acute stroke. Recent studies show that up to 52% of acute strokes are missed² and the identification of specific subtypes such as large vessel occlusion (LVO) stroke is even more challenging. Besides the well-established National Institutes of Health Stroke Scale, recently investigated in a prehospital clinical trial,³ multiple clinical scores exist to support emergency medical service personnel in quantifying and standardizing stroke symptoms into ordinal data results.⁴

Information available on sex inequity in prehospital stroke care is growing⁵; however, no clinical scale has incorporated sex differences. In a recent Australian population–based cohort study with >200 000 confirmed patients with stroke, women, especially those younger than 70 years of age, were less likely than men to receive prehospital stroke care according to standard emergency medical service protocols.⁶ More insight into sex inequities in the hyperacute management of patients with stroke is needed, and, so far, only limited data are available, which analyze performance differences of prehospital scores in women and men.

In this volume of Stroke, Ali et al⁷ have shown that there is no difference between men and women in the identification of patients with LVO using 8 stroke scales (Los Angeles Motor Scale, Rapid Arterial Occlusion Evaluation, Cincinnati Stroke Triage Assessment Tool, Cincinnati Prehospital Stroke Scale, Prehospital Acute Stroke Severity, Gaze-Face-Arm-Speech-Time, Conveniently Grasped Field Assessment Stroke Triage, and Face-Arm-Speech-Time Plus Severe Arm or Leg Motor Deficit) designed for use in the prehospital setting.

They present pooled individual patient data from 2 prospective cohort studies, the LPSS (Leiden Prehospital Stroke Study) and the PRESTO (Prehospital Triage of Patients With Suspected Stroke), which were conducted in 4 ambulance regions in the southwest Netherlands between 2018 and 2019 and were both designed as prospective, multicenter, observational cohort studies. They included patients with prehospital suspected acute stroke within 6 hours after symptom onset. In both studies, ambulance paramedics documented 11 (LPSS) or 9 (PRESTO) clinical items for every patient on a mobile application, which were used to reconstruct 8 acute LVO scores. Overall, 2358 patients were analyzed, of whom 47% were women. A final diagnosis of LVO was found in 231 patients (100 women and 131 men). Of the 8 scales investigated, the Rapid Arterial Occlusion Evaluation score had the highest positive predictive value in both sexes (0.29 in women and 0.37 in men). There was a statistically significant difference between both sexes in the sensitivity of the Los Angeles Motor Scale score, which was higher in women than in men (0.76 versus 0.63; P=0.02).

Independent of any acute LVO score or stroke subtype, only 64% of women compared with 74% of men had a correct diagnosis of stroke in the investigated cohorts, which is an alarming result potentially contributing to delays in treatment and consequently worse outcomes.

The study has several limitations. The study population was limited to those patients presenting within 6 hours after symptom onset. While the patients included are those patients identified as suspected strokes by prehospital teams, there is no information about patients, who were not identified as suspected stroke candidates at the emergency site but who later had a confirmed stroke diagnosis (false negative). Because more women present with altered mental status, headache, reduced consciousness, generally reduced condition, or dizziness,^8–13 this group could influence the performance of the scores dramatically. The Dutch health care system and stroke pathways are well established and optimized, which questions the generalizability of less elaborated systems.

This analysis and the fact that these 8 scales perform without any relevant sex inequity is good and important to know. Still, the results warrant further optimization of hyperacute stroke care with the help of clinical scales, especially in the prehospital setting.

First, these scales usually only collect basic neurological abnormalities and, hence, are superficial—and they need to be—to facilitate their implementation and attract users in difficult prehospital settings. Furthermore, although most scales are simplistic from a stroke expert perspective, in many countries due to the lack of human resources, prehospital teams comprise not only trained paramedics or emergency medical technicians but also untrained emergency assistants, who form independent ambulance crews and who might struggle identifying for example symptoms of agnosia for the Rapid Arterial Occlusion Evaluation scale or gaze deviation for the Cincinnati Stroke Triage Assessment Tool. Most clinical studies investigated the scales with teams of well-trained paramedics/emergency medical technicians or even emergency physicians.^3,14–17

Second, without increasing the knowledge about stroke of prehospital teams, all those patients with symptoms not captured by simplistic scales will always be disadvantaged and may miss out on adequate treatments. Ultimately, diagnostic identification of patients with stroke relies on the knowledge and competence of the prehospital teams involved.

A Californian state-wide database analysis of >300 000 patients identified that the probability for women to get correctly identified as suspected patients with stroke in the prehospital setting was 26% lower than for men, and this was likely caused by the differences in clinical presentations.¹⁸ A systematic review and meta-analysis of 21 observational studies with nearly 7000 patients with stroke focused on the type of symptom as the most important factor for correct prehospital diagnosis. More than a quarter of all patients with stroke missed by the prehospital teams presented with symptoms not captured by simplistic prehospital stroke scales aimed at diagnosing LVO.² Despite scales aiding our clinical judgment, competence and experience remain important factors in clinical decision-making. This is exemplified in a cohort study of 183 patients with suspected stroke, where accuracy for acute LVO detection by the clinical judgment of the emergency physician was higher than by Rapid Arterial Occlusion Evaluation and FAST-ED (Field Assessment Stroke Triage for Emergency Destination).¹⁹ The superiority of clinical judgment was also applied to the subgroup analysis of women versus men. These results, even if limited by the lack of real-life prehospital scenarios, clearly suggest the need and benefit of clinical expertise when working with patients with suspected acute stroke. Limiting prehospital stroke assessment to the simplistic scales for LVOs may result in fewer patients identified at the expense of women and may narrow down the possibilities that exist in the development of prehospital stroke competence. Currently, the most accurate prehospital stroke diagnosis can only be reached by using the concept of a mobile stroke unit, an ambulance equipped with a computed tomography scanner, a laboratory unit, telemedicine, and stroke expertise, either on board or connected remotely, but even if spreading, these ambulances will not reach all patients with suspected stroke.^20–23

There is a need for improving and standardizing training and competence of prehospital personnel in stroke recognition, including sex differences in symptom presentation. We need to harmonize pre- and in-hospital stroke educational programs and communication. Increased stroke knowledge of prehospital personnel is needed if we want to deploy the full potential of the already available hyperacute treatments and save our patients from disability.