Mechanism of injury independently predicts mortality and functional outcomes in blunt trauma patients

Document Type



General Surgery


Background: While performing trauma outcomes research, the standard with regard to the cause of injury has been to control for the “type” of trauma, that is penetrating vs. blunt. Most injury assessment schemes do not control for the “mechanism” by which a patient suffers their injury (e.g. falls, motor vehicle crashes, pedestrian struck by motor vehicle, etc). The independent relationship between mechanism of injury (MOI) and trauma outcomes is unknown. We hypothesized that patients who suffer otherwise similar and equivalent injuries demonstrate different outcomes solely due to the mechanism by which they sustained their injury.
Objective: To determine the independent relationship between mechanism of injury (MOI) and mortality and functional outcomes after blunt trauma.
Methods: Review of patients (ages 15 and above) included in the National Trauma Data Bank (NTDB) between 2001- 2005 who suffered moderate/ severe blunt trauma (New Injury Severity Score (NISS) > 9). ICD version 9, E-Codes were used to categorize patients in to one of six MOI groups. Patients with burns and penetrating trauma were excluded. Outcome measures were mortality and presence or absence of a functional deficit at discharge in three domains: Speech, Walking and Feeding. Multiple logistic regression was utilized to determine outcome differences between each MOI group and motor vehicle crash which was selected as the reference group. Patients were adjusted for age, gender, anatomic injury severity (using the NISS), physiologic injury severity upon admission (using the Revised Trauma Score), head injury (using the Relative Head Injury Severity Score), extremity injury (using the Abbreviated Injury Scale), race, insurance status, and injury intent (intentional vs. unintentional).
Results: of the 1.4 million patients included in the NTDB over the study period, 515,464 patients met our inclusion criteria. Mean age was 39 years, 65% were males and mean NISS for patients was 19. Crude mortality was 5.96% and 63% of patients had at least one functional deficit at discharge (52% had impaired walking, 16% had impaired feeding and 9% had a speech deficit). The table demonstrates how MOI independently influences outcomes after blunt trauma. Pedestrians struck by motor vehicle had worse outcomes, whereas patients who fell on the same level had better outcomes than the reference group controlling for injury severity and other known variables that influence outcomes.


This work was published before the author joined Aga Khan University


Journal of Surgical Research