Identifying patients with time-sensitive injuries: Association of mortality with increasing prehospital time

BACKGROUND: Trauma is a time-sensitive disease. However, recognizing which patients have time-critical injuries in the field is challenging. Many studies failed to identify an association between increasing prehospital time (PHT) and mortality due to evaluation of heterogenous trauma patients, as well as inherent survival bias from missed deaths in patients with long PHT. Our objective was to determine if a subset of existing trauma triage criteria can identify patients in whom mortality is associated with PHT. METHODS: Trauma patients 16 years or older transported from the scene in the National Trauma Databank 2007 to 2015 were included. Cubic spline analysis used to identify an inflection where mortality increases to identify a marginal population in which PHT is more likely associated with mortality and exclude biased patients with long PHT. Logistic regression determined the association between mortality and PHT, adjusting for demographics, transport mode, vital signs, operative interventions, and complications. Interaction terms between existing trauma triage criteria and PHT were tested, with model stratification across triage criteria with a significant interaction to determine which criteria identify patients that have increased risk of mortality associated with increasing PHT. RESULTS: Mortality risk increased in patients with total PHT of 30 minutes or less, comprising a study population of 517,863 patients. Median total PHT was 26 minutes (interquartile range, 22-28 minutes) with median Injury Severity Score of 9 (interquartile range, 4-14) and 7.4% mortality. Overall, PHT was not associated with mortality (adjusted odd ratio [AOR], 0.984 per 5-minute increase; 95% confidence interval [CI], 0.960-1.009; p = 0.20). Interaction analysis demonstrated increased mortality associated with increasing PHT for patients with systolic blood pressure less than 90 mm Hg (AOR, 1.039; 95% CI, 1.003-1.078, p = 0.04), Glasgow Coma Scale score of 8 or less (AOR, 1.047; 95% CI, 1.018-1.076; p < 0.01), or nonextremity firearm injury (AOR, 1.049; 95% CI, 1.010-1.089; p < 0.01). CONCLUSION: Patients with prehospital hypotension, Glasgow Coma Scale score of 8 or less, and nonextremity firearm injury have higher mortality with increasing PHT. These patients may have time-sensitive injuries and benefit from rapid transport to definitive care. LEVEL OF EVIDENCE: Prognostic/Epidemiologic III; Therapeutic/Care Management IV.