Aims

In recent years, many jurisdictions have legalized medicinal and/or recreational cannabis. Yet, limited information is available on the effects of cannabis commercialization (provision of legal supply of cannabis to adults through licensed retail outlets) on adverse outcomes, such as traffic fatalities. The purpose of this study was to systematically review the literature on the effects of cannabis retail outlets on traffic collisions, fatalities and other traffic-related outcomes.

Methods

Eight electronic bibliographic databases were searched (MEDLINE, PUBMED, PsychINFO, CINAHL, EMBASE, Scopus, Dissertation Abstracts, Google Scholar) to identify documents of original research on effects of cannabis retail outlets on traffic-related outcomes, including hand searches and a canvass of all members of the International Council on Alcohol, Drugs and Traffic Safety. The guidelines and rating criteria by the Scottish Intercollegiate Guidelines Network informed the review.

Results

190 documents were identified, of which nine met all inclusion/exclusion criteria. All nine studies were conducted in the US. Six studies showed some increase in adverse traffic-related outcomes for states with legalized retail outlets compared to states with no legalized cannabis outlets. Three studies showed no overall effect, although one study showed a significant reduction in collision fatalities for those 15–44 years of age. Studies using Difference-in-Difference designs, total collision fatalities rates by billion vehicle miles travelled or by cannabis positive results found positive outcomes.

Conclusions

This systematic review indicates that two thirds of reviewed studies found some positive association between cannabis commercialization and fatality outcomes. However, the few studies available and the quality grading for the studies suggest only a moderate probability of causal attribution. Future studies need move beyond examining only fatalities or assessing mere presence of cannabis; reliable measures indicating driver impairment at time of collision are needed to establish better causal attribution and to provide greater utility for policy development and implementation.

中文翻译：

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对大麻零售店对交通碰撞、死亡和其他交通相关结果的影响的系统审查

宗旨

近年来，许多司法管辖区已将药用和/或娱乐大麻合法化。然而，关于大麻商业化（通过有执照的零售店向成年人合法供应大麻）对交通死亡等不利结果的影响的信息有限。本研究的目的是系统地审查关于大麻零售店对交通碰撞、死亡和其他交通相关结果的影响的文献。

方法

搜索了八个电子书目数据库（MEDLINE、PUBMED、PsychINFO、CINAHL、EMBASE、Scopus、Dissertation Abstracts、Google Scholar）以识别关于大麻零售店对交通相关结果的影响的原始研究文件，包括手动搜索和国际酒精、毒品和交通安全委员会的所有成员。苏格兰校际指南网络的指南和评级标准为审查提供了信息。

结果

确定了 190 份文件，其中 9 份符合所有纳入/排除标准。所有九项研究均在美国进行。六项研究表明，与没有合法大麻网点的州相比，拥有合法零售网点的州与交通相关的不利后果有所增加。三项研究显示没有总体影响，但一项研究显示，15-44 岁人群的碰撞死亡人数显着减少。使用差异中差异设计的研究、十亿车辆行驶里程或大麻的总碰撞死亡率发现了积极的结果。

结论

这项系统审查表明，三分之二的审查研究发现大麻商业化与死亡结果之间存在某种正相关。然而，可用的少数研究和研究的质量分级表明因果归因的可能性只有中等。未来的研究需要超越仅检查死亡人数或仅评估大麻的存在；需要采取可靠的措施来表明发生碰撞时驾驶员的损伤，以建立更好的因果归因，并为政策制定和实施提供更大的效用。