Purpose of the study
Bystander CPR (BCPR) in out-of-hospital cardiac arrest (OCHA) significantly improves the likelihood an individual survives. Various neighbourhood characteristics where an OHCA occurs influences whether the patient receives BCPR or not1. We also need to know how the patient and event characteristics of an OHCA influence the behavioural responses of bystander witnesses to initiate BCPR to help understand differences in survival between emergency medical services (EMS).
Materials and Methods
Data for April 2014 to December 2015 was obtained from the OHCA Outcomes registry held at the University of Warwick. Using BCPR as the dependent variable, multivariate logistic regression was undertaken to examine the factors collected by ambulance services. A probability of p>0.05 was set for removal from the model. For cases that were missing data for at least one variable, hotdeck imputation was used to substitute for these data points.
Results
A number of variables, and interactions, were significantly associated with the likelihood an individual received BCPR or not. The importance of the variables was in the following order: witnessed by a bystander>location of the OHCA>gender of the OHCA patient>age of the patient. The final regression model included location out of home (ORadj 1.54), age under 65y (ORadj 1.19), OHCA occurring between 10am and 10pm (ORadj 1.25), and ambulance response time (ORadj 1.04).
Conclusions
The likelihood an OHCA patient in England will receive BCPR depends on a number of patient/event-specific factors. The most important are whether the event was witnessed by a bystander or not and whether the event was in a public place. Young patients are also more likely to receive BCPR, as are patient who arrest during daytime.
1.	Brown TP, et al. Identification of characteristics of neighbourhoods with high incidence of out-of-hospital cardiac arrest and low bystander cardiopulmonary resuscitation rates. Resuscitation 2017; 118S: e43-e4.

8 - Who Receives Bystander CPR in a Witnessed Out-of-Hospital Cardiac Arrest in England