Fig. 2

Non-linear associations between the FFP-to-RBC ratio or platelet-to-RBC ratio and in-hospital mortality in the restricted cubic spline analyses. The model was adjusted for calendar year at admission; hospital characteristics; age, sex, and body mass index at admission; Japan Coma Scale at admission; Charlson comorbidity index; ambulance use; injured regions; and the ICD-10-based injury severity score as covariates. Five transfusion ratio points (0.50, 0.75, 1.00, 1.25, and 1.50) were denoted as the knots and 1.00 was designated as the reference value. The area region represents 95% confidence intervals for the estimated adjusted odds ratios. FFP: fresh frozen plasma; RBC: red blood cell; ICD-10: International Classification of Diseases, 10th Revision