Introduction: In mature trauma systems, most trauma deaths occur soon after injury yet studies often only include patients who survive to hospital admission. These studies exclude pre-hospital deaths and introduce substantial survival bias. Understanding trauma fatalities across all phases of care is essential to identify opportunities to further improve trauma outcomes.
Methods: This retrospective cohort study analysed adult trauma fatalities attended by London's Air Ambulance from 1 January 2019 to 31 December 2020. Deaths were classified as pre-hospital if traumatic cardiac arrest occurred before hospital arrival. Timing of death was recorded as minutes from injury to arrest for pre-hospital cases and days from admission to death for in-hospital cases. A multidisciplinary panel determined the likely cause of death using clinical, radiological, and post-mortem findings.
Results: Among 3,089 adult trauma patients attended, 497 (16.1%) died. Most deaths (77.1%) occurred pre-hospital, with a median time from injury to traumatic cardiac arrest of 12 minutes (IQR 6-24). Haemorrhage and traumatic brain injury accounted for 81.9% of deaths overall, but their distribution differed markedly by phase of care: 96.2% of haemorrhage deaths occurred pre-hospital, whereas 84.2% of in-hospital deaths were due to traumatic brain injury. In addition, deaths from all other potentially reversible causes, and 95.1% of penetrating trauma deaths, occurred pre-hospital.
Conclusion: In mature trauma systems, most trauma deaths now occur before arrival in hospital, with many due to potentially reversible causes. The greatest opportunities to improve trauma outcomes now lie in the pre-hospital phase of care.
Keywords: Haemorrhage; Health system performance; Pre-hospital care; Trauma mortality; Trauma systems; Traumatic brain injury.
Serious injury is a major cause of death, especially in younger people. Although hospital trauma care has improved, most people who die after serious injury die before reaching hospital. This study examined when and why adult trauma patients died within a well-developed, organised urban trauma system. Most deaths occurred very soon after injury and usually before hospital admission, often due to severe bleeding or other conditions that can usually be treated if care is given quickly in hospital. In contrast, patients who reached hospital rarely died from these potentially treatable problems. These findings show that further reductions in trauma deaths are most likely to come from action before hospital arrival. This includes preventing violent injury, helping members of the public and first responders to control life-threatening bleeding, and ensuring access to life-saving treatments before hospital arrival, alongside rapid transport to hospital.
© The Author(s) 2026. Published by Oxford University Press on behalf of BJS Foundation Ltd.