Performance of the Lausanne Ischemic Stroke Pathway prehospital triage system in identifying acute revascularization candidates: a quality-control study

Background and objective : Appropriate identification and rapid transport to a center with revascularization capabilities are the cornerstones of prehospital care for patients with suspected acute ischemic stroke (AIS). In the Lausanne Ischemic Stroke Pathway (LISP) triage system, emergency medical service (EMS) providers use dedicated criteria to identify acute revascularization candidates and call a coordinated medical team (CMT, including a neurologist and an emergency physician), which can activate the stroke code pathway. The objective of this study was to evaluate the performance of the system in identifying acute revascularization candidates. Methods: In this retrospective single-center quality‒control study in a Swiss university-based stroke center, we included patients ≥18 y.o. from January 1st, 2019, to May 31st, 2022, for whom the EMS activated the CMT, as well as patients with AIS eligible for acute revascularization. The main outcomes were the performance of both the EMS and CMT in detecting AIS patients eligible for acute revascularization, as assessed through their respective under- and overtriage rates. A secondary outcome was the identification of alternative diagnoses in over-triaged patients. Results : We included 1071 patients, including 937 (87.5%) for whom either the CMT was called by the EMS (n=937, 87.5%) and/or presented an AIS eligible for revascularization (n=440, 41%). The overall undertriage rate of the system was 30.2% (133 patients without stroke pathway activation among the 440 patients with an AIS eligible for acute revascularization). The undertriage rate of EMS was 21.4% (94 patients for whom EMS did not call the CMT of the 440 with an AIS eligible for acute revascularization). The undertriage rate of CMT was 11.3% (39 patients without stroke code pathway activation of the 346 with an AIS eligible for acute revascularization and for whom CMT was called by the EMS). The overtriage rate of EMS was 63.1% (591 patients without an AIS eligible for acute revascularization of the 937 patients for whom CMT was called by EMS). The overtriage rate of CMT patients was 56.8% (403 patients without an AIS eligible for acute revascularization of the 710 for whom CMT activated the stroke pathway). The main alternative diagnoses in over-triaged patients were are seizures (13.9%), intracranial hemorrhages (9.9%) and functional disorders (6.5%). Conclusion : The undertriage rate in our study may be improved by the education of the EMSCMT calls by the EMS reduced overtriage. A better prehospital identification of alternative diagnoses could help identify patients without an AIS who are eligible for acute revascularization and decrease over-triage. Acceptable rates of mis-triage must be determined in each system of care.