Abstract WP233: Prehospital Stroke Screen Accuracy in a State with an Emergency Medical Services Protocol for Routing Patients to Acute Stroke Centers

Abstract

Background: A growing number of states are enacting legislation or regulations that direct emergency medical service (EMS) routing to state designated or Joint Commission Certified Stroke Centers, based on prehospital stroke screens performed by EMS providers. Objective: Assess the sensitivity and specificity of the Cincinnati Prehospital Stroke Screen (CPSS) and the Los Angeles Prehospital Stroke Screen (LAPSS) when performed by EMS providers in the context of a state-wide EMS stroke patient transport protocol. Methods: We used a validated method of deterministic matching to link a statewide Prehospital Medical Information System database, that includes prehospital stroke screen results, to a Statewide Emergency Department (ED) Surveillance System database containing ED disposition diagnosis ICD-9 codes. We compared EMS stroke screen results to the ED ICD-9 codes for ischemic and hemorrhagic stroke and TIA. Results: Over a 24 month period, we identified 3,901 linked records with a prehospital impression of acute stroke. This included 2,419 (62%) records with a completed and conclusive stroke screen result. There were 1,202 patients (50%) with a completed CPSS and 1,217 patients (50%) with a completed LAPSS. Ninety-four EMS agencies from 65 of the state’s 100 counties were represented in the complete data. The CPSS was 80% (95% CI 76-83%) sensitive and 46% (95% CI 42-50%) specific, whereas the LAPSS was 73% (95% CI 69-76%) sensitive and 42% (95% CI 38-46%) specific for identifying patients with an ED diagnosis of stroke or TIA. Conclusion: When performed and conclusively recorded by many different EMS agencies across one state, the CPSS and LAPSS had similar test characteristics. If prehospital screening is to be used to determine transport diversion to acute stroke centers, improving the specificity of these screens would be optimum.