BACKGROUND AND AIMS While cannabis use has been found to impair motor vehicle driving, the association between cannabis legalisation and motor vehicle fatalities is unclear. In Uruguay in December 2013, cannabis for recreational purposes was legalized. This study assessed the association between implementation of this law and changes in traffic fatality rates. DESIGN Interrupted time series analysis of traffic fatality rates of light motor vehicle drivers and motorcyclists in urban and rural settings. Changes are reported as step and trend effects against modelled trends in the absence of legalisation. SETTING Uruguay, Montevideo and four rural provinces (Colonia, Florida, Río Negro and San José) from January 1st , 2012 to December 31st , 2017. CASES AND MEASUREMENT Weekly traffic fatalities of light motor vehicle drivers and motorcyclists per type of vehicle. Data were gathered from the National Road Safety Agency of Uruguay and the Ministry of Transport and Public Works respectively. RESULTS Cannabis legalisation was associated with a 52.4% immediate increase (95% CI: 11.6, 93.3, p = 0.012) in the light motor vehicle driver's fatality rate. However, no significant change in the motorcyclists' fatality rate was observed. In Montevideo the legislation was associated with an absolute increase in its light motor vehicle driver's fatality rate by 0.06 (95% CI: 0.01, 0.11, P = 0.025), but no significant associations were observed in rural settings. CONCLUSIONS In Uruguay, the 2013 legislation legalizing recreational cannabis consumption may have been associated with an increase in fatal motor vehicle crashes, particularly in light motor-vehicle drivers and urban settings.

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乌拉圭大麻使用合法化与交通死亡之间的关联

背景和目的 虽然已发现使用大麻会损害机动车驾驶，但大麻合法化与机动车死亡之间的关联尚不清楚。2013 年 12 月在乌拉圭，用于娱乐目的的大麻合法化。本研究评估了该法律的实施与交通死亡率变化之间的关联。设计 城市和农村环境中轻型机动车驾驶员和摩托车手交通死亡率的中断时间序列分析。在没有合法化的情况下，变化被报告为针对模拟趋势的步骤和趋势影响。2012 年 1 月 1 日至 2017 年 12 月 31 日在乌拉圭、蒙得维的亚和四个农村省份（科洛尼亚、佛罗里达、里奥内格罗和圣何塞）进行设置。案例和测量 每种车辆的轻型机动车辆驾驶员和摩托车手的每周交通死亡人数。数据分别来自乌拉圭国家道路安全局和交通与公共工程部。结果 大麻合法化与轻型机动车辆驾驶员的死亡率立即增加 52.4%（95% CI：11.6, 93.3，p = 0.012）相关。然而，没有观察到摩托车手的死亡率有显着变化。在蒙得维的亚，立法与其轻型机动车辆驾驶员的死亡率绝对增加 0.06（95% CI：0.01、0.11，P = 0.025）有关，但在农村地区未观察到显着关联。结论 在乌拉圭，