Changes in Emergency Department Visits for Cannabis Hyperemesis Syndrome Following Recreational Cannabis Legalization and Subsequent Commercialization in Ontario, Canada

Abstract

IMPORTANCE Prior research suggests that the legalization of recreational cannabis is associated with increases in cannabis hyperemesis syndrome (CHS), but it is unclear how cannabis commercialization (ie, greater retail store access as well as increased variety and potency of cannabis products) may be associated with these changes.OBJECTIVES To examine changes in the number and characteristics of CHS emergency department (ED) visits from before to after legalization of cannabis in Ontario, Canada. DESIGN, SETTING, AND PARTICIPANTSThis repeated cross-sectional study used interrupted timeseries analyses to examine immediate and gradual changes in ED visits for CHS in Ontario, Canada, during 3 time periods: prelegalization (January 2014-September 2018), legalization with product and retail store restrictions (October 2018-February 2020), and commercialization with new products and expanded stores, which coincided with the COVID-19 pandemic (March 2020-June 2021). Data were obtained from routinely collected and linked health administrative databases. All individuals aged at least 15 years and who were eligible for Ontario's Universal Health Coverage were included. Data were analyzed between March and July 2022. MAIN OUTCOMES AND MEASURES Monthly counts of ED visits for CHS per capita.RESULTS There were 12 866 ED visits for CHS from 8140 individuals during the study. Overall, the mean (SD) age was 27.4 (10.5) years, with 2834 individuals (34.8%) aged 19 to 24 years, 4163 (51.5%) females, and 1353 individuals (16.6%) with a mental health ED visit or hospitalization in the 2 years before their first CHS ED visit. Nearly 10% of visits (1135 visits [8.8%]) led to hospital admissions.Monthly rates of CHS ED visits increased 13-fold during the 7.5-year study period, from 0.26 visits per 100 000 population in January 2014 to 3.43 visits per 100 000 population in June 2021. Legalization was not associated with an immediate or gradual change in rates of ED visits for CHS; however, commercialization during the COVID-19 pandemic period was associated with an immediate increase in rates of CHS ED visits (incidence rate ratio [IRR], 1.49; 95% CI, 1.31-1.70). During commercialization, rates of CHS ED visits increased more in women (IRR, 1.49; 95% CI, 1.16-1.92) and individuals older than the legal age of cannabis purchase (eg, age 19-24 years: IRR, 1.60; 95% CI, 1.19-2.16) than men (IRR, 1.08; 95% CI, 0.85-1.37) and individuals younger than the legal age of purchase (IRR, 0.78; 95% CI, 0.42-1.45). CONCLUSIONS AND RELEVANCEThis cross-sectional study found large increases in CHS ED visits during the period of time when the market commercialized and the COVID-19 pandemic occurred.Greater awareness of CHS symptoms by ED staff in regions where legal commercialized cannabis markets exist is indicated.

Access to legal cannabis market in Canada over the four years following non‐medical cannabis legalisation

“…While the implications of this variation are relatively unknown, a large body of literature from alcohol control [5] caution that it may result in differences in use and consequent harms. Increasing research from Canada and the United States has found that greater retail access to cannabis stores is associated with increases in cannabis use and health care visits caused by cannabis across several populations [6,7,[14][15][16].…”

“…Canadian evidence suggests minimal changes in cannabis use and consequent health care visits immediately following legalisation [5]. More recent studies suggest that cannabis use and health care visits may be increasing as the market has expanded including the phased introduction of new higher-potency products such as vapes, edibles and concentrates, which began 1 year post legalisation in October 2019 [6][7][8][9]. However, there are no published data on how retail store access has changed in Canada in years 3 and 4 following legalisation.…”

Response to Smyth & McCarron: Increases in cannabis‐attributable emergency department visits during different phases of the pre‐ and post‐legalization period are multi‐factorial

“…Importantly, while we believe that the Canadian experience regarding legalization will generalize to other countries, we highlight that legalization itself can take multiple forms. Our ongoing research suggests that regulatory decisions such as allowing or restricting cannabis marketing and promotion, retail access, product types and cannabis potency can all influence cannabis use and related health outcomes post-legalization [10][11][12][13]. Consequently, as other countries proceed towards legalization, we caution that policies that allow higher levels of commercial access risk important population-level changes in cannabis use and consequent harms.…”

The Impact of Recreational Cannabis Legalization on Cannabis Use and Associated Outcomes: A Systematic Review

“…associated with any changes in rates of emergency admissions. 80 As this attenuation occurred in Canada prior to commercialization where strict purchasing policy was in place, it may suggest that having proper regulations in place can prevent the uptick in cannabis-related emergency visits seen in U.S. studies. Other hospital-related outcomes examined included admissions for cannabis misuse and other substance use exposure.…”