Calvert Collin M, Erickson Darin
School of Public Health, Division of Epidemiology and Community Health, University of Minnesota, 1300 S. 2nd Street, Suite 300, Minneapolis, MN, 55454-1015, USA.
J Cannabis Res. 2021 Jul 7;3(1):27. doi: 10.1186/s42238-021-00085-x.
Whether recreational cannabis legalization is associated with changes in alcohol consumption (suggesting a potential substitution or complementary relationship) is a key question as cannabis policy evolves, particularly given the adverse health and social effects of alcohol use. Relatively little research has explored this question.
This study examined the association between recreational cannabis legalization and alcohol purchasing in the USA using an interrupted time series design. We used data from the Nielsen Consumer Panel (2004-2017) from 69,761 households in all 50 states to calculate monthly milliliters of pure ethanol purchased for four beverage categories (beer, wine, spirits, and all alcohol products). We used difference-in-differences models and robust cluster standard errors to compare changes in milliliters of pure ethanol purchased. We fit models for each beverage category, comparing three "policy" states that have legalized recreational cannabis (Colorado, Oregon, and Washington) to states that had not legalized recreational cannabis. In one set of models, a single control state was selected that matched pre-policy purchasing trends in the policy states. In another set, policy states were compared to all states that had not legalized recreational cannabis.
Compared to all other states that did not legalize recreational cannabis, Colorado households showed a 13% average monthly decrease in purchases of all alcoholic products combined (estimate, 0.87; CI, 0.77, 0.98) and a 6% decrease in wine (0.94; CI, 0.89, 0.99). Estimates in Washington were suggestive of an increase in spirits purchased in both the unrestricted (1.24; CI, 1.12, 1.37) and restricted sample (1.18; CI, 1.02, 1.36). Oregon showed a significant decrease in monthly spirits purchased when compared to its selected comparator state (0.87; CI, 0.77, 0.99) and to all other states without legalized recreational cannabis (0.85; CI, 0.77, 0.95).
Results suggest that alcohol and cannabis are not clearly substitutes nor complements to one-another. Future studies should examine additional states as more time passes and more post-legalization data becomes available, use cannabis purchase data and consider additional methods for control selection in quasi-experimental studies.
随着大麻政策的演变，娱乐用大麻合法化是否与酒精消费的变化相关（表明潜在的替代或互补关系）是一个关键问题，尤其是考虑到酒精使用对健康和社会的不利影响。相对较少的研究探讨了这个问题。
本研究采用中断时间序列设计，考察了美国娱乐用大麻合法化与酒精购买之间的关联。我们使用了来自尼尔森消费者面板（2004 - 2017年）的数据，这些数据来自50个州的69,761户家庭，以计算四个饮料类别（啤酒、葡萄酒、烈酒和所有酒精产品）每月购买的纯乙醇毫升数。我们使用差异 - 差异模型和稳健聚类标准误来比较纯乙醇购买毫升数的变化。我们为每个饮料类别拟合模型，将三个娱乐用大麻合法化的“政策”州（科罗拉多州、俄勒冈州和华盛顿州）与未将娱乐用大麻合法化的州进行比较。在一组模型中，选择了一个与政策州政策前购买趋势相匹配的单一对照州。在另一组模型中，将政策州与所有未将娱乐用大麻合法化的州进行比较。
与所有其他未将娱乐用大麻合法化的州相比，科罗拉多州家庭购买的所有酒精产品总量平均每月下降13%（估计值为0.87；置信区间为0.77，0.98），葡萄酒购买量下降6%（0.94；置信区间为0.89，0.99）。华盛顿州的估计值表明，在无限制样本（1.24；置信区间为1.12，1.37）和受限样本（1.18；置信区间为1.02，1.36）中，烈酒购买量均有所增加。与选定的对照州相比（0.87；置信区间为0.77，0.99）以及与所有其他未将娱乐用大麻合法化的州相比（0.85；置信区间为0.77，0.95），俄勒冈州每月购买的烈酒量显著下降。
结果表明，酒精和大麻既不是明显的替代品，也不是互补品。随着时间的推移，更多州实现合法化且有更多合法化后的数据可用，未来的研究应考察更多州，使用大麻购买数据，并在准实验研究中考虑其他选择对照的方法。
