Clinical paper Exposure-response relationship between COVID-19 incidence rate and incidence and survival of out-of-hospital cardiac arrest (OHCA)

Aim: We aimed to report the epidemiology of OHCA, bystander CPR pattern and other Utstein factors in a region in Hong Kong during the COVID-19 pandemic. In particular, we studied the relationship between COVID-19 incidence, OHCA incidence and survival outcome.Methods: This was a retrospective cohort study that used data from our registry to compare features of OHCA during pre-pandemic (Jan 2018 to Dec 2019), low-incidence pandemic (Jan 2020 to Dec 2021) and high-incidence pandemic (Jan to Mar 2022). We used multivariable logistic regres-sion to identify survival predictors.Results: Incidence of OHCA increased dramatically with surging COVID-19 incidence (65.9 vs 74.2 vs 159.2 per 100,000 population per year, p < 0.001). During the pandemic, there were more indoor OHCA (89.3% vs 92.6% vs 97.4%, p < 0.001), fewer witnessed arrest (38.5% vs 38.3% vs 29.6%, p = 0.001), and longer median time to basic life support upon receiving call (9 min vs 10 min vs 14 min, p < 0.001). There was a higher proportion of OHCA cases with bystander-CPR (26.1% vs 31.3% vs 35.3%, p < 0.001). The proportion of cases with survival to admission (STA) (30.8% vs 22.2% vs 15.4%, p < 0.001) and survival to discharge (STD) (2.2% vs 1.0% vs 0.2%, p = 0.001) were lowered. After controlling for confounders, the odds of STA was reduced by 33% and 55% during the low-incidence and high-incidence pandemic respectively.Conclusion: The increase in COVID-19 incidence had an exposure-response relationship with an increased incidence of OHCA and worsened survival outcomes.