Mechanism of Injury Predicts Patient Mortality and Impairment After Blunt Trauma

doi:10.1016/j.jss.2008.04.011

Journal of Surgical Research

Volume 153, Issue 1, 1 May 2009, Pages 138-142

https://doi.org/10.1016/j.jss.2008.04.011 Get rights and content

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.

Introduction

Trauma has typically been categorized injury in 2 broad types, blunt or penetrating. Each “type” of trauma has different epidemiology patterns, management paradigms, and outcome assessment methodologies. In penetrating trauma, injury is usually focused on the areas directly affected by the penetrating object. The effect of blunt traumatic injury may be more diffuse, and different blunt trauma “mechanisms” impart varying degrees of force and energy transfer [1].

Blunt trauma occurs in more than 80% of trauma patients [2], and can be subdivided by mechanisms of injury (MOI), which include motor vehicle crash (MVC), falls, pedestrian struck by motor vehicles, bicycle crashes, motor cycle crashes, and various other mechanisms. When added to the different patterns of velocity and energy transfer noted above, stratifying by blunt trauma mechanisms is likely necessary to study outcomes. For example, forces inflicted on a pedestrian struck by a motor vehicle may be much greater than an occupant in a MVC, in which the victim has some protection.

Mechanism of injury has proven to be useful in field triage. When used in combination with other indices, MOI has limited under-triage and over-triage of trauma patients at the injury scene [3, 4, 5]. Similarly, certain mechanisms are highly associated with specific injuries. For example, falls from a height typically result in calcaneal fractures and motor cycle crashes are highly associated with pelvic fractures [6]. Based on such research, MOI appears to be a useful variable to consider in trauma care.

However, little is know about the independent relationship between MOI and trauma outcomes among blunt trauma patients. The purpose of this study was to identify the association between mechanism of injury and outcomes following injury, specifically mortality and functional outcomes. We hypothesized that adult patients who suffer otherwise similar and equivalent blunt injuries may have disparate outcomes based on the mechanism by which they sustain their injury.

Section snippets

Study Design

This was a retrospective review of patient records in the National Trauma Data Bank (NTDB) version 6.1, which includes patients from the years 2001 to 2005. The NTDB is the largest repository of adult trauma data available for study in the United States. It is managed by the American College of Surgeons and collects cases from approximately 700 trauma centers. This study was reviewed by the Johns Hopkins University School of Medicine Institutional Review Board and approved for exempt status.

Participant Selection

Results

Of the 1,466,887 patients entered into the NTDB over the years studied, 515,464 (35%) patients met our inclusion criteria. Mean age was 39 y, 69% were male, 73% White, and 41% had commercial health insurance (Table 2).

Unintentional injury was identified as a characteristic in 99% of patients, and overall crude mortality was 5.96%. Injury severity characteristics by MOI group are described in Table 3. Mean ISS (19.4) and mortality rate (10.84%) was highest for pedestrians struck by motor

Discussion

In this study, mechanism of injury is an independent predictor of mortality and functional impairment at the time of hospital discharge. After adjusting for injury severity and other confounders and using MVC victims as a reference group, blunt trauma patients of otherwise equivalent injury severity had significantly different outcomes based on the mechanism of their injury. Specifically, pedestrians struck by a motor vehicle had increased odds of death or impaired walking and speaking, and

Acknowledgments

The authors thank Christine G. Holzmueller, B.A., for her assistance in preparation and editing of this manuscript.

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Association for Academic Surgery, 2008Mechanism of Injury Predicts Patient Mortality and Impairment After Blunt Trauma

Background

Materials and methods

Results

Conclusion

Introduction

Section snippets

Study Design

Participant Selection

Results

Discussion

Acknowledgments

Ann Emerg Med

J Am Coll Surgeons

Surgery

Cervical spine injury is highly dependent on the mechanism of injury following blunt and penetrating assault

J Trauma

Abdominal trauma—a review

Singapore Med J

Evaluation of the relationship between mechanism of injury and outcome in pediatric trauma

J Trauma

Field trauma triage: Combining mechanism of injury with the prehospital index for an improved trauma triage tool

J Trauma

Injury patterns associated with mortality following motorcycle crashes

Injury

The injury severity score: An update

J Trauma

Guide for the Uniform Data Set for Medical Rehabilitation (Including the FIM Instrument), Version 5.1

Association for Academic Surgery, 2008
Mechanism of Injury Predicts Patient Mortality and Impairment After Blunt Trauma