Injury thresholds after motor vehicle crash--important factors for patient triage and vehicle design.

INTRODUCTION

The Committee on Trauma recommends that older motor vehicle crash (MVC) victims or victims of crashes with significant vehicle intrusion of more than 12 in. be transferred to a trauma center since those older than 55 have an increased risk of death after injury. Yet, the precise injury thresholds as they relate to age, gender and velocity remain ill-defined. To maintain a low rate of under triage, reliable methods to identify patients at moderate injury risk are needed. We therefore characterized the likelihood of moderate to severe injury in MVC victims to determine the influence of age, gender and velocity.

METHODS

An analysis of drivers from the National Automotive Sampling System (1993-2001) was performed. Weighted logistic regression models were developed to predict the probability of head, leg, and torso injuries as a function of vehicle speed, age, and gender while controlling for confounders. A 10% probability of injury threshold was set and differences in velocity, gender and age were identified in terms of reaching this probability of injury threshold.

RESULTS

The analysis yielded 56,459 drivers which is equivalent to a population of 28,877,696 drivers nationwide. Restraint use, steering away prior to impact, breaking maneuver, gender, delta velocity, driver height and age were independent predictors of injury. Women had a higher velocity injury threshold than men for the 10% probability of injury cut-off to the torso or head which disappeared with increasing age. Conversely, men had a higher velocity injury threshold than women for the 10% probability of injury cut-off to the extremity which persisted even in older victims.

CONCLUSIONS

Our data indicate that age and gender must be considered in addition to crash velocity when making triage decisions. Furthermore, Federal Motor Vehicle Safety Standards may need to be modified to address the increased risk of injury among older adults at lower velocities given the increasing number of elderly drivers in the US.