Assessing the Temporal Trend in Survival to Hospital Admission Following Out-Of-Hospital Cardiac Arrest: Analysis From a Public Access Defibrillator Registry

Introduction: The AHA Get With the Guidelines Resuscitation Investigators recently identified that in-hospital cardiac arrest patients admitted during nights and weekends are less likely to survive to discharge. Our analysis aimed to determine if a similar relationship applied to out-of-hospital cardiac arrest (OHCA) patients.Methods: Worldwide data collection began in Oct 2012. Users of HeartSine SAM PAD public access defibrillators submitted electronic event data (comprising time/date of event and electrocardiogram traces) and an event report form (comprising patient demographics, location of arrest and survival to hospital outcome). First shock success was defined as termination of shockable rhythm for 5 seconds post-shock. Data was analysed using R.Results: A total of 3400 OHCA cases were collected. Median (IQR) age was 63 (50, 75) and males accounted for 72.4% of the dataset. A total of 1127 first shocks were delivered, and first shock success was 87.2% (983 shocks). Survival outcomes were reported in 2942 cases, and 783 (26.6%) patients survived to hospital admission. First shock success as a response to day of the week (weekday versus weekend [12am Saturday-11.59pm Sunday]) adjusted for patient age, gender and location of arrest, was assessed and there was no association found. When the same model was fitted with survival to hospital admission as a response to day of the week, it was determined that patients are approximately 20% less likely to survive to hospital admission at the weekend (OR=0.81, 95%CI [0.68, 0.95], p=0.01). There was a negative association between survival and OHCA occurring at home (OR=0.32, 95%CI [0.10, 0.94], p=0.03) and increasing age (per 1-year increase, OR=0.99, 95%CI [0.98, 1.00], p<0.001). Adjusting the model for time of day (morning [6am-11.59am], afternoon [12pm-5.59pm], evening [6pm-11.59pm] and night [12am-5.59am]) did not highlight an association with any particular time of day.Conclusions: OHCA patients are significantly less likely to survive to hospital admission at weekends compared to weekdays. Further analysis on the availability of PADs at professional and recreational locations and availability of trained medical rescuers at the weekend versus weekdays could account for the differences observed.