Out-of-hospital cardiac arrest caused by poisoning - A Swedish nationwide study over 15 years

Introduction: The epidemiology and outcomes for patients with an out-of-hospital cardiac arrest (OHCA) caused by poisoning are largely unknown and may differ from OHCA of other causes. The study's aim is to compare key characteristics and outcomes between OHCA caused by poisoning vs. other causes.Method: A retrospective observational study based on three Swedish national registries. All adult patients with an OHCA between January 1st 2007 and December 31st 2021 were included. The study population was divided into medical, non-medical and poisoning cause according to ICD-10-codes.Results: Of the 66,261 included OHCA (65.8% men, median 73 years), 89% were classified as medical and 11% non-medical. 47% of the non -medical OHCA were caused by poisoning, which represents 5.2% of all OHCA. Patients with an OHCA caused by poisoning were significantly younger (median 43 years), a larger proportion of men (67%), had the lowest frequency of witnessed event and shockable rhythm of the groups. The most common poisoning was poly-substance. The crude 30-day mortality for OHCA caused by poisoning was 83.7%, which was lower than in the medical (88%) and non-medical groups (93.8%). The adjusted 30-day mortality for OHCA caused by poisoning vs medical had an OR of 3.1 (95% CI 2.5-3.8) and vs non-medical OR 3.7 (95% CI 2.8-5.0). Conclusion: Patients with an OHCA caused by poisoning were younger, a larger proportion of men and had several predictors for increased mortality, yet still had a lower 30-day mortality rate when compared to other causes.