Exploring the association between initial serum alcohol concentration and polysubstance use: More than a simple "gateway drug" effect?

Introduction: Polysubstance abuse (PSA) is a significant problem affecting our society. In addition to negatively affecting the health and well-being of substance users, alcohol and/or drug abuse is also associated with heavy injury burden. The goal of this study was to determine if elevated serum alcohol (EtOH) levels on initial trauma evaluation correlate with the simultaneous presence of other substances of abuse (SOAs). We hypothesized that PSA would be more common among patients who present with EtOH levels in excess of the legal blood alcohol content (BAC) (≥0.10%).

Methods: An audit of trauma registry records from January 2009 to June 2015 was performed. Abstracted data included patient demographics, BAC measurements, all available formal determinations of urine/serum "drug screening," Glasgow Coma Scale (GCS) assessments, injury mechanism/severity, and 30-day mortality. Stratification of BAC was based on the 0.10% cutoff. Parametric and nonparametric statistical testing was performed, as appropriate, with significance set at α = 0.05.

Results: We analyzed 1550 patients (71% males, mean age: 38.7 years) who had both EtOH and SOA screening. Median GCS was 15 (interquartile range [IQR]: 14-15). Median ISS was 9 (IQR: 5-17). Overall 30-day mortality was 4.25%, with no difference between elevated (≥0.10) and normal (<0.10) EtOH groups. For the overall study sample, the median BAC was 0.10% (IQR: 0-0.13). There were 1265 (81.6%) patients with BAC <0.10% and 285 (18.4%) patients with BAC ≥0.10%. The two groups were similar in terms of mechanism of injury (both, ∼95% blunt). Patients with BAC ≥0.10% on initial trauma evaluation were significantly more likely to have the findings consistent with PSA (e.g., EtOH + additional substance) than patients with BAC <0.10% (377/1265 [29.8%] vs. 141/285 [49.5%], respectively, P < 0.001). Among polysubstance users, BAC ≥0.10% was significantly associated with cocaine, marijuana, and opioid use.

Conclusions: This study confirms that a significant proportion of trauma patients with admission BAC ≥0.10% present with the evidence of additional substance use. Cocaine and opioids were most strongly associated with acute alcohol intoxication. Our findings support the need for further research in this important area of public health concern. In addition, specific efforts should focus on primary identification, remediation of withdrawal symptoms, prevention of drug-drug interactions, and early PSA intervention.