Prehospital Point-of-Care GFAP for Detection of Intracranial Hemorrhage in Acute Nontraumatic Coma

Importance: Rapid identification of intracranial hemorrhage (ICH) in patients with acute nontraumatic coma is critical to guiding triage and early management; however, prehospital diagnostic tools remain limited. Objective: To evaluate the diagnostic accuracy of prehospital whole-blood point-of-care measurement of glial fibrillary acidic protein (GFAP) and ubiquitin carboxy-terminal hydrolase L1 (UCH-L1) for detecting ICH. Design, Setting, and Participants: This diagnostic study used data collected by a UK physician-paramedic helicopter emergency medical service between January 1, 2025, and April 30, 2026. A consecutive sample of adult patients (aged ≥16 years) presenting with acute nontraumatic coma, defined as Glasgow Coma Scale (GCS) score of 12 or less, who underwent prehospital rapid sequence induction (RSI) of anesthesia with clinical suspicion of ICH were eligible for inclusion. Patients with traumatic pathology and those without follow-up data were excluded. Patients were observed for up for 30 days from hospital admission. Data analysis was performed in June 2026. Exposure: Prehospital whole-blood point-of-care brain biomarker (GFAP and UCH-L1) testing using the i-STAT Alinity Point-of-Care Blood Analyzer (Abbott Laboratories). Main Outcome and Measures: Diagnostic accuracy of GFAP and UCH-L1 for detecting ICH, using computed tomography as the reference standard. Sensitivity, specificity, predictive value, and area under the receiver operating characteristic curve (AUC) were calculated. Results: The primary study cohort comprised 65 patients who underwent prehospital brain biomarker testing (median age, 63 [IQR, 47-69] years; 55.4% male). The median (IQR) GCS score was 4 (3-6). ICH was present in 50.8% (n = 33). Thirteen (20.0%) patients underwent neurosurgery, and the 30-day survival rate was 46.2% (n = 30). GFAP demonstrated high sensitivity (97.0%; 95% CI, 84.2%-99.9%) and discriminatory ability (AUC, 0.94; 95% CI, 0.87-0.99). UCH-L1 showed lower sensitivity (78.8%; 95% CI, 61.1%-91.0%) and specificity (18.8%; 95% CI, 7.2%-36.4%), with limited discriminatory performance. A combined biomarker approach achieved 100.0% sensitivity (95% CI, 89.4%-100.0%) and a negative predictive value of 100.0% (95% CI, 47.8%-100.0%). Conclusions and Relevance: In this diagnostic study of adults with acute nontraumatic coma undergoing prehospital RSI, point-of-care prehospital GFAP testing was feasible and demonstrated high diagnostic accuracy in detecting intracranial hemorrhage. Further prospective external validation is required to determine its association with triage, treatment decisions, and patient outcomes.