Pediatric out-of-hospital cardiac arrest (POHCA) is rare but associated with high mortality. Research is hindered by the lack of a standardized case definition, limiting data accuracy and consistency in identifying POHCA events across emergency medical services (EMS) systems. We sought to evaluate and compare three commonly used case definitions of POHCA using a large, national EMS database to assess their overlap and impact on case identification and documentation.

We performed a retrospective analysis of pediatric encounters (<18 years) from the National EMS Information System (2018–2023). Three case definitions were applied: (1) EMS documentation of cardiac arrest, (2) cardiac arrest listed as an impression or symptom, and (3) performance of cardiopulmonary resuscitation (CPR) or defibrillation. Event characteristics, interventions, and agreement between definitions were assessed.

Out of 10 million pediatric EMS activations, 61,255 (0.6 %) met at least one POHCA definition. While EMS documentation identified the majority (90 %), only 53 % of cases overlapped across all three definitions. We observed substantial agreement between definitions (Fleiss' Kappa = 0.79) but identified variability in data completeness and intervention documentation. For example, data pertaining to the return of spontaneous circulation (ROSC) was missing in 27.9 % of cases using EMS documentation, compared to 12 % using CPR/defibrillation definitions.

Differences in how POHCA events are defined within EMS datasets significantly influences case identification and the completeness of surrounding event characteristics. These inconsistencies limit the accuracy of research and hinder efforts to improve outcomes. A standardized, clearly defined approach is needed to enhance data quality and support future research in pediatric prehospital cardiac arrest.

None.