A Canadian study comparing emergency department (ED) visits in Hamilton, Ont. pre- and post cannabis legalization saw a spike in visits for acute cannabis intoxication among those aged 18 to 29, but not overall.

The finding is based on a retrospective chart review at an academic ED in which investigators assessed all visits having a cannabis-related discharge code from six months before legalization in October 2018 to six months after. The study was published last month in BMC Emergency Medicine.

While there was no difference in the overall rate of ED visits after legalization, study authors write, they did see a 56 per cent increase in visits among participants aged 18 to 29.

A chart in the study shows related ED visits post-legalization were also higher among those aged 50 to 59, but were about the same for those 60 and older and were lower for those aged 30 to 39 and 40 to 49.

According to the National Organization for the Reform of Marijuana Laws (NORML), most of the increase for visits of 18- to 29-year-olds revolved around observation within the ED. “Authors speculated that this subset of patients likely consists of “new users… seeking medical care as a result of unpleasant symptoms… which, ultimately, resolve on their own with time and reassurance,” NORML reports.

Overall, study results show that post-legalization, a larger portion of patients needed observation without interventions (25 per cent versus 48 per cent), bloodwork and imaging studies decreased (53 per cent versus 12 per cent) and treatment with benzodiazepines increased (24 per cent versus 51 per cent).

“Legalization was not associated with a change in the rate of cannabis-related ED visits in our study,” investigators write.

Additional research is needed to pin down details “regarding changing methods of cannabis ingestion and trends among specific age groups.” / PHOTO BY GETTY IMAGES

However, secondary outcomes that were considered as part of the review included the number of visits distributed by age, length of stay, co-ingestions and clinical course in the ED. Additional research is needed to pin down details “regarding changing methods of cannabis ingestion and trends among specific age groups,” the study points out.

A study published last year involving 14 urban Alberta EDs following legalization between Oct. 1, 2013, and July 31, 2019, found a small increase in physical visits and calls to a poison control centre.

“Although only three of every 1,000 ED visits within the time period were attributed to cannabis, the number of cannabis-related ED presentations increased post-legalization by 3.1 (range is 11.5 to 12.6) visits per ED per month,” study authors wrote at the time. Weed-related calls to poison control inched up and researchers “observed increases in cannabis-related hyperemesis, unintentional ingestion and individuals leaving the ED pre-treatment,” the study added.

Additionally, a study published two years ago determined that ED “visits attributable to inhaled cannabis are more frequent than those attributable to edible cannabis, although the latter is associated with more acute psychiatric visits and more ED visits than expected.”