UBC Faculty Research and Publications

Emergency department visits during the 4/20 cannabis celebration Staples, John; Merchant, Kate; Erdelyi, Shannon; Lund, Adam; Brubacher, Jeffrey


BACKGROUND: In many cities, annual "4/20" cannabis festivals occur on April 20 and often feature synchronized consumption of cannabis at 4:20 p.m. The relationship between these events and demand for emergency medical services has not been systematically studied. METHODS: We conducted a population-based retrospective cohort study in Vancouver, Canada, using ten consecutive years of data (2009 to 2018) from six regional hospitals. The number of emergency department (ED) visits between 4:20 p.m. and 11:59 p.m. on April 20 were compared to the number of visits during identical time intervals on control days one week earlier and one week later (i.e. April 13 and April 27) using negative binomial regression. RESULTS: A total of 3,468 ED visits occurred on April 20 and 6,524 ED visits occurred on control days. A non-significant increase in all-cause ED visits was observed on April 20 (adjusted relative risk, 1.06; 95% CI, 1.00 - 1.12). April 20 was associated with a significant increase in ED visits among pre-specified subgroups including a five-fold increase in visits for substance misuse and a ten-fold increase in visits for intoxication. The hospital closest to the festival site experienced a clinically and statistically significant 17% (95% CI, 5.1% - 29.6%) relative increase in ED visits on April 20 compared to control days. INTERPRETATION: Substance use at annual "4/20" festivals may be associated with an increase in emergency department visits among key subgroups and at nearby hospitals. These findings may inform harm reduction initiatives and festival medical care service planning.

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