Aims and Objectives The range of how trauma is experienced by each individual can be as varied as the injuries themselves. The aims of this study were to investigate the effect of increasing overall ISS and differences in pattern of injury on mortality and development of Multiple Organ Dysfunction Syndrome (MODS), as well as exploring how injury characteristics influence patient response and clinical journey. The potential to distinguish groups of patients likely to have poor outcomes will allow the focusing of research priorities, targeted clinical interventions, and preventative measures with the aim of ameliorating this impact.

Method and Design Prospectively collected data from 2432 patients recruited to the ACIT-II study (REC approval: 07/Q0603/29) at the Royal London Hospital were used. Patients were eligible if they arrived in the ED within two hours of injury and met local criteria for trauma team activation. Patients were categorised into injury severity groups (Control, Mild, Moderate, Severe, Critical, Super Critical) based on their ISS scores and alternatively categorised into groups of patients with similar injury patterns (A, B, C, D, E, F) using K-means clustering based on regional AIS scores. Multivariable logistic regression was performed using clinical physiology and demographic data, with final model selection based on bidirectional stepwise search.

Results and Conclusion 28 day mortality and MODS both increased with increasing injury severity, with a potential threshold value for poorer mortality outcomes at ISS ≥25. When clustered by injury pattern, groups containing more head-injured patients showed worse mortality, despite having more normal physiology at presentation. The three groups with the highest (relatively similar) median ISS values showed similar predicted probability of developing MODS despite differing injury patterns. Findings suggest that both methodologies may have relevance for assessing the relationship between injury severity and outcome, with injury pattern exerting particular influence on mortality and severity relating more to the development of MODS.