ObjectivesTo provide an overview of the demographic characteristics of patients with positive blood alcohol concentration (BAC) and to investigate the performance of brain CT scans in these patients.DesignCross-sectional study.SettingTaiwan.Participants2192 patients who had undergone a test for blood alcohol of 13 233 patients registered in the Trauma Registry System between 1 January 2009 and 31 December 2012. A BAC level of 50 mg/dL was defined as the cut-off value. Detailed information was retrieved from the patients with positive BAC (n=793) and was compared with information from those with a negative BAC (n=1399).Main outcome measuresGlasgow Coma Scale (GCS) and Injury Severity Score (ISS) as well as the performance and findings of obtained brain CT scans.ResultsPatients with positive BAC had a higher rate of face injury, but a lower GCS score, a lower rate of head and neck injury, a lower ISS and New Injury Severity Score. Alcohol use was associated with a shorter length of hospital stay (8.6 vs 11.4 days, p=0.000) in patients with an ISS of <16. Of 496 patients with positive BAC who underwent brain CT, 164 (33.1%) showed positive findings on CT scan. In contrast, of 891 patients with negative BAC who underwent brain CT, 389 (43.7%) had positive findings on CT scan. The lower percentage of positive CT scan findings in patients with positive BAC was particularly evident in patients with an ISS <16 (18.0% vs 28.8%, p=0.001).ConclusionsPatients who consumed alcohol tended to have a low GCS score and injuries that were less severe. However, given the significantly low percentage of positive findings, brain CT might be overused in these patients with less severe injuries.