The effect of the COVID-19 pandemic on the incidence and survival outcomes of EMS-witnessed out-of-hospital cardiac arrest

Aim: We sought to examine the impact of the COVID-19 pandemic on the incidence and survival outcomes of emergency medical service (EMS) -witnessed out-of-hospital cardiac arrest (OHCA) in Victoria, Australia. Methods: We performed an interrupted time-series analysis of adult EMS-witnessed OHCA patients of medical aetiology. Patients treated during the COVID-19 period (1st March 2020 to 31st December 2021) were compared to a historical comparator period (1st January 2012 and 28th Febru-ary 2020). Multivariable poisson and logistic regression models were used to examine changes in incidence and survival outcomes during the COVID-19 pandemic, respectively.Results: We included 5,034 patients, 3,976 (79.0%) in the comparator period and 1,058 (21.0%) in the COVID-19 period. Patients in the COVID-19 period had longer EMS response times, fewer public location arrests and were significantly more likely to receive mechanical CPR and laryngeal mask airways compared to the historical period (all p < 0.05). There were no significant differences in the incidence of EMS-witnessed OHCA between the comparator and COVID-19 periods (incidence rate ratio 1.06, 95% CI: 0.97-1.17, p = 0.19). Also, there was no difference in the risk-adjusted odds of survival to hospital discharge for EMS-witnessed OHCA occurring during COVID-19 period compared to the comparator period (adjusted odd ratio 1.02, 95% CI: 0.74-1.42; p = 0.90).Conclusion: Unlike the reported findings in non-EMS-witnessed OHCA populations, changes during the COVID-19 pandemic did not influence inci-dence or survival outcomes in EMS-witnessed OHCA. This may suggest that changes in clinical practice that sought to limit the use of aerosol gen-erating procedures did not influence outcomes in these patients.