Mortality differences among patients with trauma based on systolic blood pressure and pulse pressure: insights from a generalized additive model diagram

Background: Rapid recognition of shock in trauma patients is imperative for timely intervention and optimal outcomes. Conventional hemodynamic indices, such as systolic blood pressure (SBP), pulse pressure (PP) and shock index (SI), are commonly used to predict mortality but often fall short in predictive performance when assessed individually. To overcome these limitations, we applied a generalized additive model (GAM) to examine the nonlinear interaction between SBP and PP in relation to mortality risk. Methods: We conducted a retrospective cohort study using data from the Seoul Golden Time Registry (2019–2022) of trauma patients transported to 10 hospitals in Seoul. Receiver operating characteristic (ROC) analysis was employed to assess the mortality prediction by SBP, PP and SI; while no significant differences in survival prediction were observed among these indices, a notable correlation was found between SBP and SI. Consequently, a generalized additive model (GAM) was applied to evaluate the interaction between SBP and PP, with adjustment for confounding variables including age, sex and pre-hospital transport time. Results: A total of 62,680 out of 82,623 trauma patients were analyzed. ROC curve analysis revealed no significant difference in mortality prediction among SBP, PP and SI (SBP vs. PP, p = 0.8347; SBP vs. SI, p = 0.3077; PP vs. SI, p = 0.4433). GAM analysis identified a significant interaction between SBP and PP with adjusted confounding factors (p < 0.001). The interaction plot showed a bimodal relationship between SBP and mortality, with increased mortality risk associated with lower PP. Conclusions: The study confirms that the interaction between SBP and PP significantly affects mortality in trauma patients. These findings suggest that an integrated assessment of these hemodynamic indices may improve the early identification of high-risk trauma patients and optimize management decisions during pre-hospital and emergency care.

Blood pressure; Pulse pressure; Trauma; Mortality

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