BACKGROUND: This study aimed at evaluating if time for initiation of bystander cardiopulmonary resuscitation (CPR) - prior to the emergency call (CPRprior) versus during the emergency call following dispatcher-assisted CPR (CPRduring) - was associated with return of spontaneous circulation (ROSC) and 30-day survival. The secondary aim was to identify predictors of CPRprior.

METHODS: This observational study evaluated out-of-hospital cardiac arrests (OHCA) occurring in the Capital Region of Denmark from 01.01.2013 to 31.12.2013. OHCAs were linked to emergency medical dispatch centre records and corresponding emergency calls were evaluated. Multivariable logistic regression analyses were applied to evaluate the association between time for initiation of bystander CPR, ROSC, and 30-day survival. Univariable logistic regression analyses were applied to identify predictors of CPRprior.

RESULTS: The study included 548 emergency calls for OHCA patients receiving bystander CPR, 34.9% (n=191) in the CPRpriorgroup and 65.1% (n=357) in the CPRduringgroup. Multivariable analyses showed no difference in ROSC (OR=0.88, 95% CI: 0.56-1.38) or 30-day survival (OR=1.14, 95% CI: 0.68-1.92) between CPRpriorand CPRduring. Predictors positively associated with CPRpriorincluded witnessed OHCA and healthcare professional bystanders. Predictors negatively associated with CPRpriorincluded residential location, solitary bystanders, and bystanders related to the patient.

CONCLUSIONS: The majority of bystander CPR (65%) was initiated during the emergency call, following dispatcher-assisted CPR instructions. Whether bystander CPR was initiated prior to emergency call versus during the emergency call following dispatcher-assisted CPR was not associated with ROSC or 30-day survival. Dispatcher-assisted CPR was especially beneficial for the initiation of bystander CPR in residential areas.