Objective Out-of-hospital cardiac arrest (OHCA) has low survival rates with worse outcomes at night due to delayed emergency medical services (EMS) response, resource limitations, and workforce fatigue. Timely resuscitation is crucial, but logistical challenges exacerbate disparities. Since randomized trials are unfeasible, all-comers registries provide essential data to bridge evidence gaps and improve EMS protocols. This study aimed to investigate the impact of day versus night shifts on OHCA outcomes, focusing on ROSC rates, 30-day survival, and timing metrics within EMS operations.

Methods This study analyzed OHCA cases in Poland from September to November 2022 using paramedics records and national death registry data. Patients were grouped by time of cardiac arrest (on-hours: 7:00 AM–6:59 PM; off-hours: 7:00 PM–6:59 AM) and matched 1:1 using propensity score analysis (1194 pairs).

Results Our findings revealed significant disparities in OHCA outcomes between day and night shifts. ROSC rates were notably lower at night (20.9% vs. 34.8%; P = 0.01), as was 30-day survival (47.0% vs. 59.3%; P = 0.01). EMS response times were significantly longer during nighttime hours (median and interquartile range: 12.4(7.4-14.6) vs. 11.2(6.2-13.5)(minutes); P = 0.01)

Conclusions Patients with OHCA during off-hours were exposed to longer EMS response time as compared to procedures conducted during regular working hours. Furthermore, OHCA during night shift might be associated with a lower rate of ROSC and decreased 30-day survival

What’s New?Out-of-hospital cardiac arrest (OHCA) remains a critical public health challenge with significant implications for morbidity and mortality. Despite advancements in emergency medical services systems and resuscitation techniques, survival rates following OHCA remain low, particularly during nighttime hours. This study provided a clinical view from a national perspective on the impact of day versus night shifts on the clinical outcomes in patients with OHCA. Propensity score match analysis was performed to evade risk of bias in the preselection process. This study suggested detrimental outcome in OHCA treatment during nighttime as compared to regular working hours. Patients from nighttime group were associated with longer response times as well as decreased rate of return of spontaneous circulation and 30-day survival as compared to daytime. These findings underscore the importance of systemic approach to improve OHCA outcome.

The authors have declared no competing interest.

Funding Statement: This study was supported by internal research funds allocated under the announcement of the Deputy Rectors Representative for Science and International Cooperation of the Jagiellonian University Medical College for projects financed from the Ministry of Education and Science (MEiN) subsidy N41/DBS/001329.

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

Approved by the Bioethics Committee for Research Studies of the Jagiellonian University Medical College (approval no. 118.0043.1.299.2024) on September 26, 2024.

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Yes

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Email: anna.zadlouj.edu.pl, Email: monika.bednarekuj.edu.pl, Email: iza.karpinskadoctoral.uj.edu.pl, Email: grzegorz.cebulauj.edu.pl, Email: tomasz.tokarekuj.edu.pl

All data produced in the present study are available upon reasonable request to the authors