Modelling of patient outcomes after emergency treatment for out-of-hospital cardiac arrest by paramedics and community first responders

Background The Community First Responder (CFR) provides a small but important ambulance response for out-of-hospital cardiac arrest (OHCA). We aimed to test the influence of CFR attendance at OHCA as part of a regional ambulance response using separate statistical models of Return of Spontaneous Circulation (ROSC) and patient survival by Discharge Alive from hospital (DA). Methods Data were from East Midlands Ambulance Service NHS Trust, involving 9284 patients with OHCA from April 2014 to March 2016. Observational analyses were conducted on the complete records of n=1227 patients treated and transported to hospital. The outcomes we considered were the occurrence of ROSC under emergency care (55.8%) with longer term survival DA (11.8%). We controlled for waiting time (WT; the length of time between 999 and emergency service arrival at the patient’s side). We represented emergency care by total treatment time (TOT; the length of time from emergency service arrival to patient delivery to hospital); where this included any time input due to a CFR attending prior to the paramedics. Independent probit regressions were used to explain both outcomes, with inputs that included WT, TOT and whether a CFR attended. We also controlled for patient age, gender, event location, and day of week. Results For both fitted models, the coefficient estimates of WT were such that patient outcomes worsened as wait time increased; however, while expected in sign neither estimate was statistically significant (in ROSC beta=-0.007, p=0.161; in DA beta=-0.012, p=0.08). Coefficient estimates of TOT were significant (p