Indirect Negative Effects of the COVID-19 Pandemic on Out-Of-Hospital Cardiac Arrest 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 cardiopulmonary resuscitation. 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 and an initial shockable heart rhythm witnessed by a bystander. ITS analysis showed a drastic decline in PAD use and a reduction in favourable neurological outcomes all over Japan after the state of emergency was declared (relative risk [RR], 0·60; 95% confidence interval [CI], 0·49–0·72, p<0·0001 and RR, 0·79; 95% CI, 0·68–0·91; p=0·0032, respectively). 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 had an indirect negative effect on neurological outcomes in patients with OHCA as a consequence of less PAD use.Trial Registration Details: This study is registered with the University Hospital Medical Information Network Clinical Trials Registry, UMIN000009918.Funding Information: None.Declaration of Interests: We declare no conflict of interest.Ethics Approval Statement: This study was approved by the National Cerebral and Cardiovascular Center (R19040–2). We were exempted from the requirement for written informed consent from patients. Following the legal procedures prescribed by the Japanese government, the study enrolment data were provided to the Resuscitation Subcommittee of the Japanese Society of Cardiology; we only analysed de-identified data.