Emergency medical services/original researchOut-of-Hospital Stroke Screen Accuracy in a State With an Emergency Medical Services Protocol for Routing Patients to Acute Stroke Centers
Introduction
Reperfusion therapy and other advances in stroke therapy during the past 2 decades highlight the critical role of emergency medical services (EMS) in optimizing acute stroke care.1, 2, 3, 4, 5 Most important, early administration of intravenous tissue plasminogen activator in selected patients with acute ischemic stroke increases the likelihood of a favorable outcome, especially when administered within 90 minutes of symptom onset.3, 6, 7, 8 EMS protocols routing patients with acute stroke to hospitals capable of delivering intravenous tissue plasminogen activator is one strategy to improve timely use of thrombolytic therapy.1, 9, 10, 11, 12, 13 Such protocols rely on the use of sensitive and specific stroke screening scales to identify patients most likely to benefit from transport to a stroke center. The most commonly used stroke screening instruments are the Cincinnati Prehospital Stroke Scale (CPSS) and the Los Angeles Prehospital Stroke Screen (LAPSS).1, 14, 15 Although the CPSS and the LAPSS are widely promoted and broadly adopted, the generalizability and overall accuracy of the LAPSS and CPSS are unclear.1, 13, 16, 17, 18, 19, 20, 21
Many states, including North Carolina, have implemented statewide stroke patient EMS routing plans that specify that, within certain time constraints, patients with a positive stroke screen be transported to hospitals designated as acute stroke centers.11 Determining the accuracy of out-of-hospital stroke screens in such states is essential because the use of low-sensitivity screens can result in transport to hospitals unable to treat patients with thrombolytics, whereas bypassing hospitals according to false-positive screens can result in costly and inconvenient transport diversion. Among the challenges of studying stroke screen accuracy is the ability to link out-of-hospital databases containing EMS stroke screen results with hospital databases containing patient diagnostic data. PreMIS (Prehospital Medical Information System) is a statewide EMS database used throughout North Carolina.22 It includes patient identifiers and data fields for CPSS and LAPSS results. The North Carolina Disease Event Tracking and Epidemiologic Collection Tool (NC DETECT) is a deidentified statewide hospital emergency department (ED) surveillance database that includes ED diagnoses.23 Access to both of these out-of-hospital and hospital databases is unique to North Carolina. We have been successful in using deterministic matching to link PreMIS to deidentified databases such as NC DETECT.24
The purpose of this study was to conduct a statewide assessment of the accuracy of the CPSS and LAPSS in identifying stroke patients by comparing the stroke screen results in PreMIS with the ED diagnostic information contained in NC DETECT.
Section snippets
Study Design and Setting
As a substudy of a project evaluating North Carolina’s EMS routing protocol for patients with suspected stroke, we conducted a retrospective study of patients from January 1, 2009, to March 31, 2011.
Data Collection and Processing
We used PreMIS, which is a National Emergency Medical Services Information System–compliant, Internet-based system for documenting EMS service delivery and care for patients in North Carolina.22 EMS agencies collect and submit data into PreMIS by using either a Web-based interface provided at no
Characteristics of Study Subjects
The Figure provides information on the study sample. We were able to link 62% of PreMIS records to NC DETECT records. Our final study sample included CPSS or LAPSS data from 2,442 patients, generated by 117 EMS agencies from 94 of North Carolina’s 100 counties. It included 1,217 patients with CPSS data and 1,225 patients with LAPSS data. Characteristics for patients screened with the CPSS versus the LAPSS are listed in Table 1. For both stroke screens, most EMS agencies contributing data had
Limitations
Our study has several limitations. Our final study sample was limited by missing ICD-9 codes for some patients and the overall linkage rate. However, according to our previously published analysis, we are unable to postulate systematic bias involving linked versus nonlinked records that should affect our stroke screen analysis. Although we found both the CPSS and LAPSS to be reasonably sensitive, our methodology favored overestimating sensitivity, according to the selection criterion of cases
Discussion
We evaluated the accuracy of the CPSS and the LAPSS in the setting of a statewide EMS system. Although the sensitivities and specificities of the 2 scales were similar, the specificities were at best modest. Because poor specificity can result in “overtriage,” with many nonstroke patients being diverted to stroke centers, specificity assumes particular importance when stroke screens are used for transport diversion. Accepting the precept that some level of overtriage is justified to improve
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An updated review and meta-analysis of screening tools for stroke in the emergency room and prehospital setting
2022, Journal of the Neurological SciencesEuropean Resuscitation Council Guidelines 2021: First aid
2021, ResuscitationCitation Excerpt :In many of the prehospital setting studies, the stroke assessments were performed by paramedics or nurses4,5,51 so this guideline was based on extrapolation of potential benefit when these tools are used by lay people or first aid providers. The specificity of stroke recognition can be improved by using a stroke assessment tool that includes blood glucose measurement such as the LAPSS52–56 or MASS.53,54,57 (weak recommendation, low certainty evidence). However, it is recognised that not all first aid providers have access to or the skills or the authority to use a calibrated glucose measurement device.
2020 International Consensus on First Aid Science With Treatment Recommendations
2020, ResuscitationCitation Excerpt :Of patients who had the scale applied, 19.1% received thrombolytic therapy compared with 7.5% who did not have the scale applied (RR, 2.56; 95% CI, 1.02–6.45). For the important outcome of recognition of stroke (diagnostic studies, outcome defined as correct stroke diagnosis), we identified 19 observational studies62–65,68–71,73–82,84 including 8153 participants, studying 9 different screening tools (FAST, LAPSS, OPSS, CPSS, ROSIER, MASS, BEFAST, MedPACS, PreHAST). All studies used the same positivity threshold for each scale (1 or greater).
Emergency medical services for acute ischemic stroke: Hub-and-spoke model versus exclusive care in comprehensive centers
2019, Journal of Clinical NeuroscienceCitation Excerpt :This approach puts the burden on EMS to recognize signs of LVO, through published pre-hospital grading scales [7–9]. However, this proposition has been met with significant resistance from physicians, pointing out the significant risk of misclassification [10–14]. Of all patients presenting with neurologic compromise only a small minority suffers from an LVO, while available pre-hospital grading scales have only moderate sensitivity and specificity, even in controlled settings.
Derivation and Validation of the Emergency Medical Stroke Assessment and Comparison of Large Vessel Occlusion Scales
2018, Journal of Stroke and Cerebrovascular DiseasesCitation Excerpt :Prehospital stroke screens, including the Cincinnati Prehospital Stroke Scale and the Los Angeles Prehospital Stroke Screen, were developed to help distinguish stroke from stroke mimic.2-6 Unfortunately, first-generation prehospital stroke screens have had limited accuracy when they have been tested in the field.7-10 Recently completed randomized clinical trials have demonstrated the efficacy of endovascular therapy (ET) with stent retrievers versus IV t-PA alone in patients with large vessel occlusion (LVO) and salvageable tissue, generally in patients presenting with a National Institutes of Health Stroke Scale (NIHSS) greater than or equal to 6 with groin puncture less than 6 hours of ischemic stroke onset.11-16
Recent Endovascular Stroke Trials and Their Impact on Stroke Systems of Care
2016, Journal of the American College of Cardiology
Please see page 510 for the Editor’s Capsule Summary of this article.
Supervising editor: Donald M. Yealy, MD
Author contributions: AWA conceived the study and obtained research funding. SW managed the data. SW, WDR, and JS provided statistical advice. SW analyzed the data. AWA drafted the article, and all authors contributed to its revision. AWA takes responsibility for the paper as a whole.
Funding and support: By Annals policy, all authors are required to disclose any and all commercial, financial, and other relationships in any way related to the subject of this article as per ICMJE conflict of interest guidelines (see www.icmje.org). The authors have stated that no such relationships exist and provided the following details: This work was funded by the 2011-2012 EMF/Genentech Regionalization and Stroke Care Grant.
The NCDETECT Data Oversight Committee does not take responsibility for the scientific validity or accuracy of methodology, results, statistical analyses, or conclusions presented.
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