The "mortality ascent": Hourly risk of death for hemodynamically unstable trauma patients at Level II versus Level i trauma centers

BACKGROUND Severely injured trauma patients have higher in-hospital mortality at Level II versus Level I trauma centers (TCs). To better understand these differences, we sought to determine if there were any periods during which hemodynamically unstable trauma patients are at higher risk of death at Level II versus Level I TCs within the first 24 hours postadmission. STUDY DESIGN Trauma patients aged 18 years to 64 years, with Injury Severity Score of 15 or greater, systolic blood pressure less than 90 mm Hg at admission, and treated at Level II or Level I TCs, were identified using the 2007 to 2012 National Trauma Data Bank. Burn patients, transfers, and patients dead on arrival were excluded. Log-binomial regression models, adjusted for patient- and hospital-level confounders, were used to compare mortality at Level II versus Level I TCs over the first 24 hours postadmission. RESULTS Of 13,846 hemodynamically unstable patients, 4,212 (30.4%) were treated at 149 Level II TCs, and 9,634 (69.6%) at 116 Level I TCs. Within the first 24 hours, 3,059 (22.1%) patients died. In risk-adjusted models, mortality risk was significantly elevated at Level II versus Level I TCs during the 24 hours postadmission (relative risk, 1.08; 95% confidence interval, 1.01-1.16). Hourly mortality risk was significantly different between Level II and Level I TCs during 4 hours to 7 hours postadmission, with a maximal difference at 7 hours (relative risk, 1.70; 95% confidence interval, 1.23-2.36) and comparable mortality risk beyond 7 hours postadmission. CONCLUSION The 4-hour to 7-hour time window postadmission is critical for hemodynamically unstable trauma patients. Variations in available treatment modalities may account for higher relative mortality at Level II TCs during this time. Further investigation to elucidate specific risk factors for mortality during this period may lead to reductions in in-hospital mortality among hemodynamically unstable trauma patients. Level of Evidence Therapeutic/care management, level IV.