237 Relationship between prehospital time and 24-hour mortality following injury in patients with major trauma in New Zealand

<h3>Background</h3> Time is an important determinant of outcomes for individuals following trauma. Optimising prehospital trauma systems and care, such as (where appropriate) reducing prehospital times, and ensuring patients get to the appropriate receiving facility are necessary in order to reduce serious injury-related mortality and morbidity. <h3>Objective</h3> To explore the relationship between time spent in the prehospital phase and 24-hour mortality following injury in patients with major trauma in New Zealand (NZ). <h3>Methods</h3> This retrospectively designed prospective cohort study analysing routinely collected data included hospitalised patients aged 84 years or less attended by an Emergency Medical Services (EMS) provider in NZ for major trauma between 1 December 2016 and 30 November 2018. Modified Poisson regression models considered total prehospital time and EMS time intervals, and were adjusted by patient sociodemographic, triage and injury characteristics. <h3>Results</h3> 3,033 patients met the eligibility criteria; 3% (n=99) died within 24 hours following injury. Univariate analysis indicated that total prehospital time greater than 60 minutes was a predictor of survival, reducing the risk of death by 49% (Relative Risk [RR]: 0.51; 95%CI: 0.35–0.76). Response times greater than 14 minutes, on-scene times between 30–45 minutes and transport times of 10 minutes or more were independent predictors of lower risk of death. In the multivariable analysis after adjusting for patient sociodemographic, triage and injury characteristics, response times between 5–10 minutes (adjusted RR [aRR]: 0.39; 95%CI: 0.18–0.84) or greater than 14 minutes (aRR: 0.37; 95%CI: 0.18–0.80) compared to response times less than 5 minutes, predicted survival. <h3>Conclusion</h3> Although longer total prehospital times were found to predict reduced 24-hour mortality, analysis of the components of prehospital time was less conclusive and highlighted the importance of factors such as age, triage, and other related-injury factors, namely the severity of trauma. Further research is necessary to examine in more detail other factors (such as vital signs, length of hospital stay, etc) that may impact the relationship between EMS times and mortality.