Background: Different mechanisms of injury (MOI), such as motor vehicle crashes, falls, or pedestrians struck by motor vehicle impart varying degrees of force and energy transfer that may impact outcomes. This study analyzed the independent relationship between MOI and mortality and functional outcomes following blunt trauma among adults.
Materials and methods: Retrospective review of blunt trauma patients 15 y and older in the National Trauma Data Bank from 2001 to 2005. Primary outcome measures were mortality and presence of functional deficit in speech, walking, or feeding at discharge. MOI categories, identified by ICD-9 E codes, were motor vehicle crash, pedestrian struck by motor vehicle, motorcycle crash, falls at same level and from any height, and bicycle crash. A multiple regression analysis was performed adjusting for patient demographics and injury severity variables with motor vehicle crash as the reference mechanism group.
Results: Over the period studied, 515,464 patients met inclusion criteria. Mean Injury Severity Score (16.9), mortality rate (11%), and extremity injury (20%) were highest among pedestrians struck by motor vehicle, and head injury (16%) highest for motorcyclists. Overall, 52% had impaired ambulation, 16% impaired feeding, and 10% impaired speech. Adjusted odds of death, impaired walking, and impaired speaking were highest for pedestrians struck by motor vehicle, and impaired feeding highest for motorcyclists.
Conclusion: After adjusting for confounders, MOI was found to independently predict mortality and functional impairment at hospital discharge. Current injury assessment models could be greatly enhanced by including MOI, and we propose routine adjustment for injury mechanism in trauma outcomes research.