Association Between Immediate Defibrillation and Outcomes in Shockable Out-of-Hospital Cardiac Arrest: A Propensity Score Analysis.

Objectives: This study aimed to examine the association between the timing of defibrillation by emergency medical service (EMS) and out-of-hospital cardiac arrest (OHCA) patient prognosis using a nationwide database.

Methods: We included patients with non-traumatic OHCA aged ≥15 years from 2010 to 2019, with an initial shockable rhythm, who received EMS defibrillation. Patients were divided into 2 groups: defibrillation within 2 min of cardiopulmonary resuscitation (CPR; immediate defibrillation) or after 2 min (delayed defibrillation). The primary outcome was 1-month survival. We set the primary exposure to immediate defibrillation and employed a 1:1 propensity score matching. Multiple logistic regression analysis estimated the adjusted odds ratio (AOR) and 95% confidence interval (CI) for exposure and outcomes.

Results: After propensity score matching, 16,970 patients were included in each group. The 1-month survival were 32.5% and 29.1% for immediate defibrillation and delayed defibrillation, respectively. Immediate defibrillation was significantly associated with 1-month survival compared to delayed defibrillation (AOR [95% CI], 1.18 [1.12, 1.24]).

Conclusions: Defibrillation within 2 min of starting CPR was associated with 1-month survival, emphasizing the importance of immediate defibrillation.