The value of the difference between ED and prehospital vital signs in predicting outcome in trauma

Introduction: Traditional vital signs are seen as an important part of trauma assessment, despite their poor predictive value in this regard. Objective: This study evaluated whether the difference between systolic blood pressure (SBP), heart rate (HR), respiratory rate (RR) and shock index (SI) taken in the emergency department (ED) and prehospital can predict 48 h mortality postadmission following trauma. Methods: Retrospective cohort was obtained from the Trauma Audit and Research Network. Subjects were excluded if head or spinal injuries, prehospital intubation or CPR were present. Main outcome was 48 h mortality. The difference (delta, Δ) between ED and prehospital values were used as study variables (ie, ΔSI=SI-ED minus SI-prehospital). Accuracy was assessed using area under receiver operator characteristic curve (AUROC). AUROC coordinates were used to identify 95% specificity cut points and described further using sensitivity and likelihood ratios (LRs). Results: Significant AUROC statistics were revealed for ΔSBP (0.57) and Δ RR (0.56) for the full sample, ΔSBP (0.62) and ΔSI (0.65) for moderate, and ΔRR (0.6) for severe injury. Best LRs were 3.4 and 2.4 for ΔRR and ΔSI, respectively, but sensitivities were low (<=26%). Cut point values for ΔSBP, Δ RR and ΔSI were 37 mm Hg, 8 breaths/min and 0.2, respectively. Discussion: ΔSBP and ΔRR performed best overall, but ΔSI performed best in the moderate injury group, suggesting earlier identification with ΔSI. Use of Δ values result in good rule-in of 48 h mortality and may supplement trauma treatment decisions.