Accuracy of EEG Slow Wave Activity in Predicting Favorable Outcome in Patients With Hypoxic Brain Injury—A Protocol for a Substudy of the STEPCARE Trial

Background: Early restitution of electroencephalogram (EEG) slow wave activity (SWA) may be able to predict favorable functional outcome after cardiac arrest. SWA can be monitored using the C-Trend Index, a recently developed dynamic numerical index computed using commercially available medical device software. Methods: This is a pre-planned prospective substudy of the randomized controlled Sedation, TEmperature and Pressure after Cardiac Arrest and REsuscitation (STEPCARE) trial. With a factorial design, the STEPCARE trial evaluates the effects of three different interventions (sedation, temperature management, and mean arterial blood pressure) on functional outcomes in adult out-of-hospital cardiac arrest (OHCA) patients. We will record continuous EEG (cEEG) starting as early as possible after ICU admission. We will compare the accuracy (the proportion of correct predictions of all predictions) of C-Trend Index with that of blinded retrospective visual analysis of cEEG at 12 h after return of spontaneous circulation in predicting favorable functional outcome (modified Rankin Scale 0–3) 6 months after cardiac arrest. We aim to recruit 300 patients to show noninferiority in prognostic accuracy of the C-Trend Index compared with the visual analysis of cEEG, using a 2% limit for noninferiority. Furthermore, we will assess whether the therapeutic intervention related to sedation, carried out as a part of the STEPCARE trial modifies the performance of the EEG-based predictors. Conclusion: The study will compare the accuracy of SWA measured using C-Trend Index with the gold standard, visual analysis of cEEG, in predicting favorable functional outcome after OHCA. The study will also assess the effect of the sedation intervention of the STEPCARE trial on the predictive accuracy of C-Trend Index. If the accuracy of the C-Trend Index is non-inferior to the comparator's, it may provide a feasible and easy-to-learn bedside method, especially in hospitals with limited availability of neurophysiology expertise. Trial Registration: ClinicalTrials.gov identifier: NCT06564675.