Background: Patient age is well recognized as a factor that contributes to increased mortality risk among trauma patients. Less well recognized is the potential that the strength of the effects of other risk factors that increase mortality risk may depend on a patient's age. This study examines whether the statistical relationship between trauma patient survival and key mortality risk factors varies significantly by patient age in years, across mechanisms of injury.
Methods: The statistical interaction between age and values of key risk factors included in the Trauma Quality Improvement Program mortality risk adjustment model is assessed using patient data included in the 2008 National Trauma Data Bank National Sample Program. Multivariable logistic regression analysis is used to assess the statistical significance of the interaction effect on patient morality risk for key mortality risk factors and patient age in years, across mechanisms of injury.
Results: Statistically significant interactions (p < 0.01) occurred between age and each of the selected risk factors, for each common mechanism of injury. Differences also occurred in the direction of the interactions between age and selected risk factors, across mechanism of injury.
Conclusion: The effects of key risk factors included in trauma patient mortality risk adjustment models vary depending on patient age in years, for each commonly occurring mechanism of injury. Statistical models assessing patient mortality risk could be meaningfully improved by accounting for these interaction effects.
Level of evidence: Prognostic and epidemiologic study, level III.