Evaluation of the Prehospital Diagnostic Accuracy of a novel Point-of - Care Test for NT-proBNP, D-Dimer and H-FABP and Large-Vessel Occlusion (LVO) Risk Assessment (LVOCheck-EVA): A Protocol for a Multicenter Prospective Observational Study in Patients Suspected of Having a Stroke

Kian Röhrs^1,2*Maximilian Kaffes^1,2Fulvio Bondi¹Martina Zuber¹Dorothee Kübler-Weller¹Lisa Haacke¹Robert Röhle¹Erin Dirk Sprünken¹Eugen Schwabauer³Matthias Wendt⁴Carmen de Jesus Gil⁵Jean-charles Sanchez^5,6Joan Montaner^7,8,9Heinrich Audebert^1,2Joachim E. Weber^1,10,11,2

• ¹Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, and Humboldt-Universität zu Berlin, Berlin, Germany
• ²Center for Stroke Research Berlin, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany, Berlin, Germany
• ³Vivantes Klinikum Neukolln, Berlin, Germany
• ⁴BG Klinikum Unfallkrankenhaus Berlin gGmbH, Berlin, Germany
• ⁵Advanced Brain Companion Diagnostics S.L. (ABCDx), Project Partner, Barcelona, Spain., Barcelona, Spain
• ⁶Department of Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland., Geneva, Switzerland
• ⁷Institute de Biomedicine of Seville, IBiS/Hospital Universitario Virgen del Rocío/CSIC/University of Seville, Seville, Spain, Seville, Spain
• ⁸Department of Neurology, Hospital Universitario Virgen Macarena, Seville, Spain, Seville, Spain
• ⁹Advanced Brain Companion Diagnostics S.L. (ABCDx), Project Partner, Barcelona, Spain, Barcelona, Spain
• ¹⁰Berlin Institute of Health at Charite, Berlin, Germany
• ¹¹German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany, Berlin, Germany

Introduction: Acute ischemic stroke is a leading cause of permanent disability in adults. Rapid initiation of thrombolytic therapy, as well as immediate access to mechanical thrombectomy for patients with large-vessel occlusion (LVO), are critical determinants of favorable outcomes. While Mobile Stroke Units (MSUs) have demonstrated efficacy in improving outcomes, their deployment is often constrained to urban environments due to cost-efficiency considerations. Blood biomarkers offer a cost-effective alternative for stroke diagnosis. Especially for patients with LVO, a prehospital biomarker-based identification could enable a streamlined transport directly to thrombectomy-capable stroke centers. In this study, we evaluate the diagnostic accuracy and feasibility of a novel point-of-care test (POCT) in predicting LVO stroke from blood samples of patients with suspected stroke in a prehospital setting. The test integrates a blood-based multiplex lateral flow assay with clinical decision support software, accessible through a Mobile Application. Trial registration: German Clinical Trials Register, DRKS-ID: DRKS00037840. Methods and analysis: This multicenter prospective observational study includes 800 patients with suspected stroke within 24 hours after symptom onset. Participants will be recruited at three MSU sites in Berlin, Germany. Prehospital blood samples will be analyzed in the ambulance using the LVOCheck device. The test achieves its performance by quantifying the blood levels of the biomarkers NT-proBNP, D-Dimer, and H-FABP, and inputting these concentrations, along with neurological assessment scores and patient-specific information, to output predictive information on the probability of LVO. Additional clinical data will be documented in electronic case report forms. The diagnostic performance of LVOCheck will be evaluated through statistical analysis of the combined biomarker and clinical data, including assessment of sensitivity, specificity, and predictive models. Discussion: This real-world study aims to evaluate the diagnostic accuracy and feasibility of LVOCheck, a portable, multiplex POCT at prehospital settings in the prediction of acute LVO diagnosis and triage of suspected acute LVO stroke patients. Utilizing MSUs as recruiting sites enables the analysis of ultra-early biomarker levels from prehospital blood samples. A practical POCT could provide additional biochemical information to support prehospital LVO identification in the future, thereby potentially assisting emergency medical services in transport decisions regarding direct transfer to thrombectomy-capable centers.