Cannabis presentations to the emergency department after motor vehicle crashes in the era of legalization for recreational use

Choo, Esther / Nishijima, Daniel / Trent, Stacy / Eichelberger, Angela H. / Ye, Yu / Audett, Ariane / Brasel, Karen / Kazmierczak, Steve / Cherpitel, Cheryl J.
Journal of Safety Research
In press

Introduction: There is limited research on the impact of cannabis liberalization laws on health-related behaviors and healthcare utilization. Our objectives were to examine cannabis and alcohol use among adult injured drivers presenting to emergency departments (EDs) in cannabis-legal states in order to capture an expanded profile of cannabis use in this population and evaluate differences in crash characteristics among those using cannabis alone and in combination with alcohol.
Methods: This was a cross-sectional study of visits by drivers involved in motor vehicle crashes (MVCs) who presented to the ED following the event. Event-related and usual drug and alcohol use information was obtained from consenting ED patients presenting immediately after the MVC using a detailed interviewer-administered computerized questionnaire (RedCap). Blood and breathalyzer data were obtained and the electronic medical record reviewed. We examined frequency and types of acute cannabis and alcohol use, crash mechanisms and characteristics, and frequency and types of past-year use. Our primary method of determining cannabis and alcohol use was self-report; as a sensitivity analysis, we used measurements from biological samples (biosamples).
Results: Overall, 8% percent of drivers reported cannabis use in the 8 hours prior to MVCs across three cannabis-legal states, either cannabis alone or in combination with alcohol; however, a higher proportion (18%) were positive by biosample criteria. There was a high level of heterogeneity in types of marijuana used, with joint, spliff, or blunt use by only 24% of the population reporting cannabis use in the 8 hours before presentation and 48% of the population reporting past-year use. High-risk crash features (moderate- to high-speed collisions, rollover, vehicle ejection, intrusion, single vehicle) were common in MVCs associated with cannabis, as they were for alcohol use and co-ingestion; however, while patients injured seriously enough to require admission were less likely to report cannabis use (7% vs. 9%), they were more likely to report alcohol use (17% vs. 10%).
Conclusions: Cannabis use was common among patients presenting to the ED after MVCs in this sample of cannabis-legal states. The differences between self-report and biosample data for cannabis and alcohol use in this population were significant and supports the need to use both means of assessing acute use in future studies, particularly when done in this context, where legal and medical concerns may affect reporting. However, the limitations of laboratory data when used as an objective measure must also be acknowledged. The heterogeneity of use captured supports altering our standard screening processes. Differences in reported drug patterns across sites supports the influence of contextual factors in use and health outcomes.