Optimizing prehospital chest compression strategies: The Impact of Compression Fraction on survival in out‐of‐hospital cardiac arrest patients, a retrospective cohort study

Abstract Background Chest compression fraction (CCF) is a key metric of cardiopulmonary resuscitation (CPR) quality. Although a higher CCF is generally associated with better outcomes after a cardiac arrest, the optimal threshold and potential ceiling effect remain unclear, particularly in the prehospital setting. Objective We investigated the association between prehospital CCF and outcomes after an out‐of‐hospital cardiac arrest (OHCA). Methods This retrospective cohort study included adults with nontraumatic OHCA managed by six emergency medical service agencies in Taoyuan from January 2023 to December 2024. CCF the proportion of total resuscitation time spent on chest compressions was calculated as the interval between automated external defibrillator power‐on and LUCAS device deployment. Patients who received continuous on‐scene mechanical CPR were stratified into lower (<80%) and higher (≥80%) CCF groups. The primary outcome was sustained (≥24 h) return of spontaneous circulation (ROSC), whereas the secondary outcome was favorable neurological outcomes at discharge (cerebral performance category score: 1 or 2). A covariate‐adjusted restricted cubic spline model was used to explore nonlinear associations. Results This study included 742 patients. The lower and higher CCF groups comprised 508 and 234 patients, respectively. The sustained ROSC rate was 22.0% in the overall cohort. It was higher in the higher CCF group than in the lower CCF group (25.6% vs. 20.3%; p = 0.10). Approximately 2.8% of all patients achieved favorable neurological outcomes, with no significant between‐group differences ( p = 0.25). A significant nonlinear association was noted between CCF and sustained ROSC ( p for nonlinearity = 0.005), with peak benefit at approximately 67% CCF and diminishing returns beyond 80%. Conclusion Prehospital CCF exhibited a significant nonlinear association with sustained ROSC. These findings challenge the assumption that a higher CCF is always better. Future guidelines should incorporate personalized CCF targets to optimize CPR outcomes.