Background: Although most medical centers are equipped for 24-h care, some "middle of the night" services may not be as robust as they are during daylight hours. This would have potential impact upon certain outcome measurements in trauma patients. The purpose of this paper was to assess the effect of patient arrival time at hospital emergency departments on in-hospital survival following trauma.
Materials and methods: Data of patients, 18 years of age or older, with no evidence that they were transferred to or from that center were obtained from the National Trauma Data Bank Version 7.0. Patients meeting the above criteria were excluded if there was no valid mortality status, arrival time information, injury severity score, or trauma center designation. The primary analyses investigated the association of arrival time and trauma center level on mortality. Relative risks of mortality versus patient arrival time and trauma level were determined after controlling for age, gender, race, comorbidities, injury, region of the country, and year of admission.
Results: In total, 601,388 or 71.7% of the 838,284 eligible patients were retained. The overall in-hospital mortality rate was 4.7%. The 6 p.m. to 6 a.m. time period had a significantly higher adjusted relative risk for in-hospital mortality than the 6 a.m. to 6 p.m. time frame (ARR=1.18, P<;0.0001). This pattern held across trauma center levels, but was the weakest at Level I and the strongest at Level III/IV centers (Level I: ARR=1.10, Level II: ARR=1.14, and combined Level III/IV: ARR=1.32, all P<0.0001).
Conclusion: Hospital arrival between midnight and 6 a.m. was associated with a higher mortality rate than other times of the day. This relationship held true across all trauma center levels. This information may warrant a redistribution of hospital resources across all time periods of the day.
Keywords: Mortality rates; time of day; trauma center level designation.