Background: Prompt initiation of bystander cardiopulmonary resuscitation (CPR) is critical to survival for out-of-hospital cardiac arrest (OHCA). However, the association between delays in bystander CPR and OHCA survival is poorly understood.
Methods: In this observational study using a nationally representative US registry, we identified patients who received bystander CPR from a layperson for a witnessed OHCA from 2013 to 2021. Hierarchical logistic regression was used to estimate the association between time to CPR (<1 minute versus 2-3, 4-5, 6-7, 8-9, and ≥10-minute intervals) and survival to hospital discharge and favorable neurological survival (survival to discharge with cerebral performance category of 1 or 2 [ie, without severe neurological disability]).
Results: Of 78 048 patients with a witnessed OHCA treated with bystander CPR, the mean age was 63.5±15.7 years and 25, 197 (32.3%) were women. The median time to bystander CPR was 2 (1-5) minutes, with 10% of patients having a≥10-minute delay before initiation of CPR. Overall, 15 000 (19.2%) patients survived to hospital discharge and 13 159 (16.9%) had favorable neurological survival. There was a graded inverse relationship between time to bystander CPR and survival to hospital discharge (P for trend <0.001). Compared with patients who received CPR within 1 minute, those with a time to CPR of 2 to 3 minutes were 9% less likely to survive to discharge (adjusted odds ratio, 0.91 [95% CI, 0.87-0.95]) and those with a time to CPR 4 to 5 minutes were 27% less likely to survive (adjusted odds ratio, 0.73 [95% CI, 0.68-0.77]). A similar graded inverse relationship was found between time to bystander CPR and favorable neurological survival (P for trend <0.001).
Conclusions: Among patients with witnessed OHCA, there was a dose-response relationship between delays in bystander initiation of CPR and lower survival rates.
Keywords: cardiopulmonary resuscitation; logistic model; out-of-hospital cardiac arrest; probability; registries; survival rate.