An assessment of predictors of out-of-hospital cardiac arrest (OHCA) survival found that the overall survival rate of, and key predictors of survival for, OHCA have not changed in 30 years.
The authors analyzed 79 studies published between 1984 and 2008 that discussed key factors in OHCA survival in adults. Based on previous research, key factors were: bystanders or EMS witnessing an OHCA; bystander CPR; patients being in ventricular fibrillation/ventricular tachycardia; or achieved return of spontaneous circulation.
Overall survival rate to hospital admission was 23.8 percent, while survival rate to hospital discharge was 7.6 percent. The five key factors consistently predicted better rates of survival—return of spontaneous circulation was the most significant predictor. The number of cases needed to save one life ranged from 16 to 23 for EMS-witnessed or 17 to 71 for bystander-witnessed OHCA cases, and 24 to 36 cases for those receiving bystander CPR.
In spite of technological progress and increased research spending, OHCA survival rates have not significantly improved between 1984 and 2008. The authors attribute this lack of improvement to a decrease in ventricular fibrillation arrests, an aging population and longer EMS response times in cities. Improving OHCA survival should center on improving pre-hospital cardiac care, especially the effective interventions of witnesses.