Prevalence of cannabis use among trauma patients presenting to the emergency department: A systematic review and meta-analysis

Cannabis use is a potentially important exposure among trauma patients presenting to emergency departments (EDs), yet reported prevalence varies widely across regions and study designs. We aimed to estimate the pooled prevalence of cannabis use among trauma patients presenting to the ED and to examine variation by geographic region and cannabis detection method. We searched PubMed, Embase, Web of Science, and the Cochrane Library from inception to June 30, 2025. Observational studies reporting the prevalence of cannabis use among ED trauma patients were included. Two reviewers independently screened studies, extracted data, and assessed risk of bias using the Joanna Briggs Institute checklist for prevalence studies. Pooled prevalence estimates were calculated using a random-effects model, with prespecified subgroup analyses by geographic region, overall risk of bias, and cannabis detection method. Thirty studies published between 2000 and 2025, comprising >6 million ED encounters, were included. The pooled prevalence of cannabis use among trauma patients presenting to the ED was 4.2% (95% CI 4.0%–4.4%), with substantial heterogeneity (I2 > 95%). Studies using biological toxicology testing reported higher prevalence estimates than studies relying on administrative diagnostic coding. Prevalence varied by region, with higher pooled estimates observed in South America and lower estimates in Asia and North America. Cannabis use is present in a measurable proportion of ED trauma patients, but prevalence estimates vary widely, largely reflecting differences in detection methods and case definitions. Standardized, biologically based screening approaches are needed to improve comparability and interpretation in acute trauma care.