Predictors of 24-Hour Mortality in Patients with Major Trauma Attended by Emergency Medical Services in New Zealand

Abstract

Background Major trauma is a significant contributor to morbidity and mortality. The provision of optimal prehospital Emergency Medical Services (EMS) care and timely transfer to advanced-level hospital care are vital to increase the likelihood of survival of following major trauma.

Objective To identify factors that predict 24-hour mortality in patients with major trauma who were attended by EMS at the scene of injury in New Zealand (NZ).

Methods Analysis of routinely collected data (major trauma registry and EMS providers) from a retrospectively designed prospective cohort study was undertaken. Patients aged 84 years or less who experienced major trauma between December 2016 and November 2018 that were attended by an EMS provider in NZ were included. Factors predictive of 24-hour mortality were explored using modified Poisson regression.

Results 3,033 patients met the eligibility criteria; 3% (n=99) died within 24 hours following injury. Univariate analysis suggested that being aged between 80 and 84, being triaged by EMS as having threat to life injuries (purple/red), having an ISS greater than 24, experiencing non-blunt trauma or intentional injury, having one or more comorbidities, and having one or more previous hospital admissions increased the risk of mortality. Following adjustment for the characteristics of injury, the relationships between mortality 24 hours after injury with age (80–84 years cf. 0–14 years) (Adjusted Relative Risk [aRR]: 13.17; 95%CI: 2.96–58.55), triage (purple/red cf. orange/green/grey) (aRR: 2.19; 95%CI: 1.38–3.47), having one or two previous hospital admissions compared to no having admissions (aRR: 1.83; 95%CI: 1.13–2.97), experiencing non-blunt trauma in relation to experiencing blunt trauma (aRR: 2.64; 95%CI: 1.16–6.02) and having an ISS greater than 24 compared to having an ISS of 24 or less (aRR: 10.19; 95%CI: 6.03–17.20) remained.

Conclusion Our results suggest that mortality within 24 hours following major injury is predicted by injury severity, a patient’s age, and other injury-related factors such as mechanism of injury and injury intent. However, of these, severity of injury was the strongest predictor in this study. The findings reinforce the need for continued primary prevention efforts and the rapid EMS assessment and management of those with severe injuries in the prehospital setting.