The Danish Drowning Cohort: Evaluation of Data Availability for Fatal and Non-Fatal Drowning Incidents

Aim: The Danish Drowning Cohort has collected nationwide prehospital data on fatal and non-fatal drowning incidents in Denmark. The database contains 47 variables: 22 variables from the existing Utstein Drowning Template and 25 additional variables based on the availability in the Danish prehospital medical records. This study aimed to estimate the availability of data (ie, data completeness) for the predefined prehospital registry variables in the Danish Drowning Cohort and the availability of Utstein variables in the subpopulations of drowning patients with and without out-of-hospital cardiac arrest (OHCA). Methods: This study included all fatal and non-fatal drownings in the Danish Drowning Cohort from January 1, 2016, to December 31, 2023. Data availability rates were reported for all variables in the Danish Drowning Cohort and the Utstein variables in the subpopulations of patients with and without OHCA, presented as medians with interquartile ranges (IQR). Results: A total of 1,664 drowning patients were analysed (697, 42% with OHCA). The median data availability rate in the Danish Drowning Cohort was 100% (IQR: 88– 100%): 100% (IQR: 81– 100%) for non-OHCA and 100% (IQR: 87– 100%) for OHCA patients. Among the subset of 22 available Utstein variables, the overall data availability was 95% (IQR: 75– 100%). For the 17 Utstein variables applicable to both non-OHCA and OHCA, the availability rate was 92% (IQR 76– 100%) in non-OHCA cases and 88% (IQR 78– 100%) in OHCA cases, with no difference between groups. Overall, 21 of 79 (26%) Utstein variables were unavailable in the Danish setting. Conclusion: The Danish Drowning Cohort contained nationwide data on fatal and non-fatal drowning patients with high degrees of availability. Data availability was high for most variables defined in the Utstein Drowning Template, both for drowning patients with and without OHCA. However, 21 of 79 Utstein variables were unavailable despite the Danish high-resource healthcare setting. Plain Language Summary: Drowning is a serious public health problem, and high-quality data are essential to improve prevention and medical care. In Denmark, the Danish Drowning Cohort collects nationwide data on fatal and non-fatal drowning patients treated by the Emergency Medical Services or Search And Rescue helicopters. The database contains 47 variables: 22 variables from the existing Utstein Drowning Template and 25 additional variables based on the availability in the Danish prehospital medical records. This cohort was established to ensure centralised collection of structured and comprehensive drowning data with minimal bias as an alternative to resource-intensive studies with on-site data collection. This study aimed to estimate the availability of data for the Danish Drowning Cohort and the availability of Utstein variables in the subpopulations of drowning patients with and without out-of-hospital cardiac arrest (OHCA). This study included all 1,664 drowning patients registered in the Danish Drowning Cohort between 2016 and 2023, 42% with out-of-hospital cardiac arrest, and examined the availability of data for each predefined data item. The Danish Drowning Cohort contained nationwide data on fatal and non-fatal drowning patients with high degrees of availability. Data availability was high for most variables defined in the Utstein Drowning Template, both for drowning patients with and without OHCA. However, 21 of 79 Utstein variables were unavailable despite the Danish high-resource healthcare setting. Keywords: drowning, helicopter emergency medical services, HEMS, emergency medical services, EMS, prehospital care, out-of-hospital cardiac arrest, OHCA, data accuracy