Epinephrine administration for adult out-of-hospital cardiac arrest patients with refractory shockable rhythm: time-dependent propensity score-sequential matching analysis from a nationwide population-based registry.

BACKGROUND: Little is known about the effect of prehospital epinephrine administration in out-of-hospital cardiac arrest (OHCA) patients with refractory shockable rhythm, for whom initial defibrillation was unsuccessful.

METHODS: This study using Japanese nationwide population-based registry included all adult OHCA patients aged ≥18 years with refractory shockable rhythm between January 2014 and December 2017. Patients with or without epinephrine during cardiac arrest were sequentially matched using a risk set matching based on the time-dependent propensity scores within the same minute. The primary outcome was 1-month survival. The secondary outcomes included 1-month survival with favourable neurological outcome (cerebral performance category scale: 1 or 2) and prehospital return of spontaneous circulation (ROSC).

RESULTS: Of the 499,944 patients registered in the database during the study period, 22,877 were included. Among them, 8,467 (37.0%) received epinephrine. After time-dependent propensity score-sequential matching, 16,798 patients were included in the matched cohort. In the matched cohort, positive associations were observed between epinephrine and 1-month survival (epinephrine: 17.3% [1,454/8,399] vs. no epinephrine: 14.6% [1,224/8,399]; RR 1.22 [95% confidence interval {CI}, 1.13-1.32]) and prehospital ROSC (epinephrine: 22.2% [1,868/8,399] vs. no epinephrine: 10.7% [900/8399]; RR, 2.07 [95% CI, 1.91-2.25]). No significant positive association was observed between epinephrine and favourable neurological outcome (epinephrine: 7.8% [654/8,399] vs. no epinephrine: 7.1% [611/8,399]; RR, 1.13 [95% CI, 0.998-1.27]).

CONCLUSIONS: Using the nationwide population-based registry with time-dependent propensity score-sequential matching analysis, prehospital epinephrine administration in adult OHCA patients with refractory shockable rhythm was positively associated with 1-month survival and prehospital ROSC.