Changes in neurological outcomes of out-of-hospital cardiac arrest during the COVID-19 pandemic in Japan: a population-based nationwide observational study

Background: There is growing interest in the indirect negative effects of coronavirus disease 2019 (COVID-19) on mortality. We aimed to assess its indirect effect on out-of-hospital cardiac arrest (OHCA) outcomes. Methods: We analysed a prospective nationwide registry of 506,935 patients with OHCA between 2017 and 2020. The primary outcome was favourable neurological outcome (Cerebral Performance Category 1 or 2) at 30 days. The secondary outcomes were public access defibrillation (PAD) and bystander-initiated chest compression. We performed an interrupted time series (ITS) analysis to assess changes in the trends of these outcomes around the declaration of a state of emergency (April 7 – May 25, 2020). We also performed a subgroup analysis stratified by infection spread status. Findings: We identified 21,868 patients with OHCA witnessed by a bystander who had an initial shockable heart rhythm. ITS analysis showed a drastic decline in PAD use (relative risk [RR], 0.60; 95% confidence interval [CI], 0.49–0.72; p < 0.0001) and a reduction in favourable neurological outcomes (RR, 0.79; 95% CI, 0.68–0.91; p = 0.0032) all over Japan after the state of emergency was declared when compared with the equivalent time period in previous years. The decline in favourable neurological outcomes was more pronounced in areas with COVID-19 spread than in areas without spread (RR, 0.70; 95% CI, 0.58–0.86 vs. RR, 0.87; 95% CI, 0.72–1.03; p for effect modification = 0.019). Interpretation: COVID-19 is associated with worse neurological outcomes and less PAD use in patients with OHCA. Funding: None.