The Midnight Gap: Nighttime is associated with detrimental outcome in out-of-hospital cardiac arrests in Poland

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.