Temporal Differences in Out-Of-Hospital Cardiac Arrest Incidence and Survival
Background—Understanding temporal differences in the incidence and outcomes of out-of-hospital cardiac arrest (OHCA) has important implications for developing preventative strategies and optimizing systems for OHCA care.
Methods and Results—We studied 18,588 OHCAs of presumed cardiac etiology in patients ≥18 years who received resuscitative efforts by emergency medical services (EMS) and were enrolled in the Cardiac Arrest Registry to Enhance Survival (CARES) from 10/01/2005-12/31/2010. We evaluated temporal variability in OHCA incidence and survival to hospital discharge. There was significant variability in the frequency of OHCA by hour of the day (p<0.001), day of the week (p<0.001), and month of the year (p<0.001), with the highest incidence occurring during the daytime, from Friday to Monday, in December. Survival to hospital discharge was lowest for OHCA occurring overnight (2301-0700h; 7.1%) versus daytime (0701-1500h; 10.8%) versus evening (1501-2300h; 11.3%) (p<0.001), and during the winter (8.8%) versus spring (11.1%) versus summer (11.0%) versus fall (10.0%) (p<0.001). There was no difference in survival to hospital discharge between OHCA occurring on weekends and weekdays (9.5% vs. 10.4%, p=0.06). After multivariable adjustment for age, sex, race, witness status, layperson resuscitation, first monitored cardiac rhythm and EMS response time, compared with daytime and spring, survival to hospital discharge remained lowest for OHCA occurring overnight (OR 0.81, 95% CI 0.70-0.95, p=0.008) and during the winter (OR 0.81, 95% CI 0.70-0.94, p=0.006), respectively.
Conclusions—There is significant temporal variability in the incidence of and survival after OHCA. The relative contribution of patient pathophysiology, likelihood of being observed, pre-hospital and hospital based resuscitative factors deserves further exploration.
- Received May 29, 2013.
- Revision received September 3, 2013.
- Accepted September 10, 2013.