Patterns of Cannabis Use Before and After Legalization in Canada

Objectives: With the legalization of nonmedicinal cannabis in 2018, it is important to understand how cannabis use has changed postlegalization. Legalization of cannabis also allows a further understanding of associations between cannabis use and sex, age, smoking, and vaping. Since cannabis is provincially regulated, provincial comparisons may help to understand the implications of various policy options. Methods: Data from the 2017 Canadian Tobacco, Alcohol, and Drugs Survey provided a prelegalization baseline for prevalence of cannabis use (n= 16,349). The 2019 Canadian Tobacco and Nicotine Survey was used as a postlegalization comparison (n= 8,614). The cannabis items had different wording, necessitating an approximation for the past 30-day prevalence in 2017. Variables of interest included sex, age, province, cigarette smoking status, and vaping. Results: The past 30-day prevalence of cannabis use increased from approximately 9% in 2017 to nearly 11% (95% confidence intervals: 10.1, 11.7) in 2019. However, due to the approximation of the 2017 frequency, it was not possible to confirm that this increase was statistically significant. Expected associations between cannabis use and sex, age, smoking, and vaping were found in both 2017 and 2019. Provinces that allow personal cultivation of cannabis had a higher frequency of use in 2019, odds ratio = 1.58 (95% confidence intervals: 1.27, 1.95). No differences in use were seen in provinces adopting different sales models. Conclusions: The prevalence of cannabis use in the Canadian population has increased from 2017 to 2019 by approximately 2% in absolute terms. Few differences were seen between provinces in 2019, despite differing regulatory approaches.