School of Pharmacy, Memorial University of Newfoundland, Health Science Centre, St. John's, Canada.
Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Canada.
Cannabis Cannabinoid Res. 2024 Feb;9(1):335-342. doi: 10.1089/can.2022.0227. Epub 2023 Jan 31.
As part of its recreational cannabis legalization in October 2018, Canada imposed an excise tax of 10% (or $1 a gram, whichever is higher) on both recreational and medical cannabis. There is little evidence to inform the ongoing debate on whether the legalization had adverse impacts on medical cannabis use. We used an interrupted time series design and data on medical cannabis shipments (i.e., mail-order deliveries of cannabis from a licensed producer to a patient authorized to obtain medical cannabis) in Canada between quarter 1 of 2014 and quarter 1 of 2020. We examined changes in medical cannabis shipments after Canada's recreational cannabis legalization both across Canada and for each province. As this study used publicly available, province-level aggregate data, ethics approval was not required. Recreational cannabis legalization was associated with significant reductions in medical cannabis use in 7 out of 10 Canadian provinces. Compared with the counterfactual estimated from prelegalization trends, the reduction in quarter 1 of 2020 varied from 500 shipments per 100,000 population (95% CI=312-688 shipments per 100,000 population) or 32% (95% CI=22-43%) in Newfoundland and Labrador to 3,778 shipments per 100,000 population (95% CI=2,972-4,585 shipments per 100,000 population) or 74% (95% CI=68-79%) in Alberta. At the national level, the number of medical cannabis shipments decreased by 823 per 100,000 population (95% CI=725-921 shipments per 100,000 population) or 48% (95% CI=45-52%). Recreational cannabis legalization was associated with reductions in medical cannabis use. Our findings call for policy attention to address possible adverse impacts of recreational cannabis legalization on medical cannabis users.
作为 2018 年 10 月休闲大麻合法化的一部分，加拿大对休闲大麻和医用大麻征收 10%的消费税（或每克 1 加元，以较高者为准）。目前几乎没有证据表明休闲大麻合法化对医用大麻使用有不利影响，这一问题仍在持续争论中。我们使用中断时间序列设计，分析了 2014 年第 1 季度至 2020 年第 1 季度加拿大医用大麻发货量（即从许可生产商向获得医用大麻授权的患者邮寄的大麻）的数据。我们研究了加拿大休闲大麻合法化后，在全国范围内以及每个省份医用大麻发货量的变化情况。由于本研究使用的是公开的省级汇总数据，因此无需伦理批准。在 10 个加拿大省份中，有 7 个省份的休闲大麻合法化与医用大麻使用量的显著下降有关。与从法律实施前的趋势估计的反事实情况相比，2020 年第 1 季度的降幅在纽芬兰和拉布拉多为每 10 万人减少 500 次发货（95%CI=312-688 次发货/每 10 万人）或 32%（95%CI=22-43%），而在艾伯塔省则为每 10 万人增加 3778 次发货（95%CI=2972-4585 次发货/每 10 万人）或 74%（95%CI=68-79%）。在全国范围内，医用大麻发货量减少了 823 次/每 10 万人（95%CI=725-921 次发货/每 10 万人）或 48%（95%CI=45-52%）。休闲大麻合法化与医用大麻使用量的减少有关。我们的研究结果呼吁政策关注休闲大麻合法化对医用大麻使用者可能产生的不利影响。
