Elevated blood alcohol impacts hospital mortality following motorcycle injury: A National Trauma Data Bank analysis

Background: Motorcyclists who drink and drive are at a higher risk of death and disability than other types of drivers. The purpose of this study was to query a national trauma database to evaluate the impact of elevated blood alcohol concentration (BAC) on outcomes in patients who sustained injury following a motorcycle crash.

Methods: The National Trauma Data Bank (NTDB) data was accessed from 2012 to 2014. Patients ≥ 18 years of age who sustained a traumatic injury following a motorcycle accident with a confirmed blood alcohol test at the time of arrival to the hospital were included. Other variables examined were: sex, race, injury severity score (ISS), and initial Glasgow Coma Scale motor score (GCSMOT), systolic blood pressure (SBP, mm Hg), SBP <90, and comorbidities. Patients with a blood alcohol concentration (BAC) at or beyond the legal limit (0.08 g/dL) comprised the "alcohol positive" group, while those with a BAC confirmed negative comprised the "alcohol negative" group. The patients who tested BAC < 0.08 g/dl were excluded from the analysis. The primary outcome of the study was in-hospital mortality. Univariate followed by propensity matched analysis was performed. All p-values were 2 sided and p-values < 0.05 were considered statistically significant.

Results: Of 113,843 patients involved in motorcycle crash, 67,183 patients underwent BAC testing. The majority (68.52%) tested negative, 21.14% tested positive above the legal limit and remaining 10.34% tested with a BAC <0.08 g/dl . A total of 29,922 patients, satisfied the inclusion criteria for final analysis. After propensity score matching, there was 100% improvement on standardized mean difference on matching variables (age, sex, race).However, differences continued between the groups on, SBP < 90, ISS and GCSMOT. The hospital mortality rates were 3.1% vs 3.9% (P < 0.001) between alcohol negative and the alcohol positive groups, respectively. The odds ratio of mortality in alcohol positive group was 1.27 (95% CI: 1.07, 1.53) and the absolute risk difference in hospital mortality was 0.008 (CI: 0.002, 0.014).

Conclusion: Patients who tested with a BAC above the legal limit sustained a higher injury severity score and higher in-hospital mortality compared to patients who tested negative.