Abstract
BACKGROUND: The use of mechanism of injury as a predictor of injury outcome presents practical challenges because this variable may be missing or inaccurate in many databases. The purpose of this study was to determine the importance of mechanism of injury as a predictor of mortality among injured children. METHODS: The records of children (<15-y-old) sustaining a blunt injury were obtained from the National Trauma Data Bank. Models predicting injury mortality were developed using mechanism of injury and injury coding using either abbreviated injury scale post-dot values (low-dimensional injury coding) or injury International Classification of Diseases, Ninth Revision codes and their two-way interactions (high-dimensional injury coding). Model performance with and without inclusion of mechanism of injury was compared for both coding schemes, and the relative importance of mechanism of injury as a variable in each model type was evaluated. RESULTS: Among 62,569 records, a mortality rate of 0.9% was observed. Inclusion of mechanism of injury improved model performance when using low-dimensional injury coding but was associated with no improvement when using high-dimensional injury coding. Mechanism of injury contributed to 28% of model variance when using low-dimensional injury coding and <1% when high-dimensional injury coding was used. CONCLUSIONS: Although mechanism of injury may be an important predictor of injury mortality among children sustaining blunt trauma, its importance as a predictor of mortality depends on the approach used for injury coding. Mechanism of injury is not an essential predictor of outcome after injury when coding schemes are used that better characterize injuries sustained after blunt pediatric trauma.