Delays in Cardiopulmonary Resuscitation, Defibrillation, and Epinephrine Administration in Out-of-Hospital Cardiac Arrest　― Composite Time-Dependent Effects of Prehospital Interventions on 30-Day Favorable Neurological Outcomes and Social Implications From a Prospective Nationwide Population-Based Cohort Study

Background: Our study investigated the prognostic impacts of the interval between collapse and the initiation of cardiopulmonary resuscitation (CPR), and subsequent intervals to defibrillation or epinephrine administration, on 30-day favorable neurological outcomes following out-of-hospital cardiac arrest (OHCA).Methods and Results: This nationwide population-based cohort study used the All Japan Utstein Registry, encompassing OHCA patients in Japan between January 2006 and December 2021. The primary outcome was 30-day favorable neurological outcomes, defined as Cerebral Performance Category 1 or 2. Three-dimensional plots and multivariable logistic regression models were used to assess the time-dependent prognostic impacts of prehospital CPR interventions. In all, 184,731 OHCA patients (86,246 with shockable rhythm and 98,485 with non-shockable rhythm) were included in the study. Three-dimensional plots revealed that the interval between collapse and initiation of CPR, and subsequent intervals to defibrillation or epinephrine, were independently associated with 30-day favorable neurological outcomes in the groups with shockable and non-shockable rhythms, respectively (P