Bystander CPR and Long-Term Survival in Older Adults With Out-of-Hospital Cardiac Arrest

Background: Most studies on bystander cardiopulmonary resuscitation (CPR) for out-of-hospital cardiac arrest (OHCA) have focused on in-hospital or short-term survival. Objectives: The purpose of this study was to examine the association between bystander CPR and long-term survival outcomes for OHCA. Methods: Within the Cardiac Arrest Registry to Enhance Survival, we identified 152,653 patients with OHCA ≥65 years of age or older. Using multivariable hierarchical logistic regression, we first examined the association between bystander CPR and in-hospital survival. Then, among those surviving to discharge and linked to Medicare files, we evaluated the association between bystander CPR and long-term mortality over 5 years using multivariable Cox regression. Results: Overall, 58,464 (38.3%) received bystander CPR. Patients receiving bystander CPR were more likely to have an OHCA that was witnessed, in a public location, and with an initial shockable rhythm. Bystander CPR was associated with a 24% higher likelihood of surviving to hospital discharge (10.2% vs 5.5%; adjusted relative risk: 1.24 [95% CI: 1.19-1.29]; P < 0.001), and this survival benefit was similar (interaction P = 0.24) for those who were 65 to 74, 75 to 84, and ≥85 years of age. Among patients surviving to hospital discharge (median follow-up of 31 months), bystander CPR was additionally associated with lower long-term mortality vs those without bystander CPR (adjusted hazard ratio: 0.78 [95% CI: 0.73-0.84]; P < 0.001), and this benefit was also consistent across age groups (interaction P = 0.13). Conclusions: In older adults with OHCA, bystander CPR was associated with higher rates of in-hospital survival. This survival benefit was not attenuated by competing mortality risks but increased in magnitude after hospital discharge.