The association between emergency medical service personnel's out-of-hospital cardiac arrest case volume and patient outcomes: A cohort study.

BACKGROUND Out-of-hospital cardiac arrest (OHCA) is one of the most critical emergencies for emergency medical service (EMS) personnel, yet it is rarely encountered in everyday practice. Resuscitation skills may decay over time, potentially leading to suboptimal OHCA treatment. This study aimed to assess the association between EMS personnel exposure to OHCA resuscitation and patient outcomes.

METHODS This cohort study included adult OHCA patients in Denmark from 2016 to 2023, where attending EMS personnel could be identified. The exposure of interest was the number of OHCA cases attended in the preceding year by EMS personnel in the first arriving EMS unit. The primary outcome was 30-day survival. A generalized linear model, adjusted for patient demographics and OHCA characteristics, was applied using generalized estimating equations to account for correlation within EMS units and within EMS personnel.

RESULTS Complete data were available for 16,931 OHCA cases, attended by 3,449 EMS personnel during the study period. The median (Q1;Q3) annual OHCA exposure per EMS personnel in the first arriving unit was 5 (3;8) cases. Increasing annual OHCA case volume was not associated with 30-day survival (adjusted risk ratio [aRR] 1.000, 95% confidence interval [CI]: 0.995;1.004) or any return of spontaneous circulation (aRR 1.001, 95% CI: 0.998;1.003).

CONCLUSIONS EMS personnel's OHCA case volume in the preceding year was not associated with an improved 30-day survival.