Patient age affects sex-based differences in post-traumatic mortality: a national trauma registry study in Japan

Purpose Sex-based differences in post-traumatic mortality have been widely discussed for quite some time. We hypothesized that age-related pathophysiologic changes would affect sex-based differences in post-traumatic mortality and aimed to verify the hypothesis using a nationwide trauma registry in Japan. Methods This was a retrospective analysis of trauma patients registered in The Japanese Trauma Data Bank. We stratified the study population into the following three subsets based on age: (1) pediatric subset (age ≤ 14), (2) adult subset (age 15–50) and (3) senior adult subset (age ≥ 51). We evaluated both sex-based differences in mortality in each subset separately using multivariate logistic regression analysis and the two-way interaction effect for predicted survival between the continuous increase of age and the sexes using a nonlinear multivariate regression model. Results We included 122,819 trauma patients who fulfilled the inclusion criteria and classified them into the 3 subsets according to age. Male patients were more likely to die compared to female patients only in the senior adult subset (adjusted odds ratio: 1.26; 95% confidence interval: 1.18–1.36), whereas there were no statistically significant differences in the other two subsets. Furthermore, non-linear logistic regression analysis revealed that predicted survival probability in male patients decreased more sharply in accordance with the increase of age compared to that in female patients (p for interaction: 0.051). Conclusion Age-related change in post-traumatic mortality was significantly different between males and females, and male patients had a relatively higher risk of death in the older population.