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Background and Aims: In 2013, Uruguay became the first country to legalize and regulate the production and distribution of cannabis for recreational use. We measured whether Uruguay's non‐commercial model of recreational cannabis legalization was associated with changes in the prevalence of risky and frequent cannabis use among secondary school students. Design: We used data from repeated cross‐sectional surveys of secondary students in Uruguay and Chile (2007–2018). Using a difference‐in‐difference approach, we evaluated changes in the prevalence of past‐year, past‐month, any risky and frequent cannabis use following enactment (2014) and implementation (2016) of cannabis legalization among the full sample of secondary students and among students who reported past‐year/month use. We examined changes separately for students ages 12 to 17, and students for whom cannabis became legally accessible, ages 18 to 21. Setting: Uruguay and Chile (2007–2018). Participants: Secondary school students in 8th, 10th and 12th grade (n = 204 730). Measurements Past‐year and past‐month cannabis use; any risky cannabis use measured with the Cannabis Abuse Screening Test (CAST); and frequent cannabis use (10+ days in the past‐month). Findings We found a decrease in past‐year and past‐month use following enactment or implementation. Among students ages 18 to 21, post‐enactment, we observed a transitory increase in 2014 that decreased thereafter for: any risky use among those who reported past‐year use (prevalence difference [PD] = 13.5%; 95% CI: 2.0, 24.9), frequent use in the full sample (PD = 4.5%; 95% CI: 1.0, 8.1), and frequent use among those who reported past‐month use (PD = 16.8%; 95% CI: 1.9, 31.8). Conclusion: The legalization of recreational cannabis in Uruguay was not associated with overall increases in either past‐year/past‐month cannabis use or with multi‐year changes in any risky and frequent cannabis use among young people. [ABSTRACT FROM AUTHOR]

Background and aim: In Uruguay, residents age 18 and older seeking legal cannabis must register with the government and choose one of three supply mechanisms: self‐cultivation, non‐profit cannabis clubs or pharmacies. This is the first paper to measure the association between type of legal cannabis supply mechanism and traffic crashes involving injuries. Design Ecological study using ordinary least squares regression to examine how department‐level variation in registrations (overall and by type) is associated with traffic crashes involving injuries. Setting: Uruguay. Cases 532 department‐quarters. Measurements Quarterly cannabis registration counts at the department level and incident‐level traffic crash data were obtained from government agencies. The analyses controlled for department‐level economic and demographic characteristics and, as a robustness check, we included traffic violations involving alcohol for departments reporting this information. Department‐level data on crashes, registrations and alcohol violations were denominated by the number of residents ages 18 and older. Findings From 2013 to 2019, the average number of registrations at the department‐quarter level per 10 000 residents age 18 and older for self‐cultivation, club membership and pharmacy purchasing were 17.7 (SD = 16.8), 3.6 (SD = 8.6), and 25.1 (SD = 50.4), respectively. In our multivariate regression analyses, we did not find a statistically significant association between the total number of registrations and traffic crashes with injuries (β = −0.007; P = 0.398; 95% CI = −0.023, 0.01). Analyses focused on the specific supply mechanisms found a consistent, positive and statistically significant association between the number of individuals registered as self‐cultivators and the number of traffic crashes with injuries (β = 0.194; P = 0.008; 95% CI = 0.058, 0.329). Associations for other supply mechanisms were inconsistent across the various model specifications. Conclusions: In Uruguay, the number of people allowed to self‐cultivate cannabis is positively associated with traffic crashes involving injuries. Individual‐level analyses are needed to assess better the factors underlying this association. [ABSTRACT FROM AUTHOR]

Background and aims: Debates regarding lowering the blood alcohol concentration (BAC) limit for drivers are intensifying in the United States and other countries, and the World Health Organization recommends that the limit for adults should be 0.05%. In January 2016, Uruguay implemented a law setting a zero BAC limit for all drivers. This study aimed to assess the effect of this policy on the frequency of moderate/severe injury and fatal traffic crashes. Design A quasi‐experimental study in which a synthetic control model was used with controls consisting of local areas in Chile as the counterfactual for outcomes in Uruguay, matched across population counts and pre‐intervention period outcomes. Sensitivity analyses were also conducted. Setting: Uruguay and Chile. Cases Panel data with crash counts by outcome per locality‐month (2013–2017). Intervention and comparator: A zero blood alcohol concentration law implemented on 9 January 2016 in Uruguay, alongside a continued 0.03 g/dl BAC threshold in Chile. Measurements Per‐capita moderate/severe injury (i.e. moderate or severe), severe injury and fatal crashes (2013–2017). Findings Our base synthetic control model results suggested a reduction in fatal crashes at 12 months [20.9%; P‐value = 0.018, 95% confidence interval (CI) = −0.340, −0.061]. Moderate/severe injury crashes did not decrease significantly (10.2%, P = 0.312, 95% CI = −0.282, 0.075). The estimated effect at 24 months was smaller and with larger confidence intervals for fatal crashes (14%; P = 0.048, 95% CI = −0.246, −0.026) and largely unchanged for moderate/severe injury crashes (−9.4%, P = 0.302, 95% CI = −0.248, 0.058). Difference‐in‐differences analyses yielded similar results. As a sensitivity test, a synthetic control model relying on an inferior treatment–control match pre‐intervention (measured by mean squared error) yielded similar‐sized differences that were not statistically significant. Conclusions: Implementation of a law setting a zero blood alcohol concentration threshold for all drivers in Uruguay appears to have resulted in a reduction in fatal crashes during the following 12 and 24 months. [ABSTRACT FROM AUTHOR]

Background and Aims: Uruguay and Chile have the highest levels of marijuana use in Latin America, and have experienced consistent increases during the last two decades. We aim to calculate separate age–period–cohort (APC) effects for past‐year marijuana use in Uruguay and Chile, which have similar epidemiologica, and demographic profiles but diverging paths in cannabis regulation. Design: APC study in which period and cohort effects were estimated as first derivative deviations from their linear age trend, separately by country and gender. Setting: Uruguay and Chile. Participants: General population between 15 and 64 years. Measurements Past‐year marijuana use from household surveys with five repeated cross‐sections between 2001 and 2018 in Uruguay (median n = 4616) and 13 between 1994 and 2018 in Chile (median n = 15 895). Findings Marijuana use prevalence in both countries peaked at 20–24 years of age and increased consistently across calendar years. Period effects were strong and positive, indicating that increases in use were evident across age groups. Relative to 2006 (reference year), Chilean period effects were approximately 48% lower in 1994 and approximately four times higher in 2018; in Uruguay, these effects were approximately 56% lower in 2001 and almost quadrupled in 2018. We observed non‐linear cohort effects in Chile and similar patterns in Uruguay for the overall sample and women. In both countries, marijuana use increased for cohorts born between the mid‐1970s and early 1990s, even in the context of rising period effects. Prevalence was consistently larger for men, but period increases were stronger in women. Conclusions: Age–period–cohort effects on past‐year marijuana use appear to have been similar in Chile and Uruguay, decreasing with age and increasing over time at heterogeneous growth rates depending on gender and cohort. Current levels of marijuana use, including age and gender disparities, seem to be associated with recent common historical events in these two countries. [ABSTRACT FROM AUTHOR]

Aims: Amid changing marijuana policies in the Southern Cone, we examined relationships between marijuana-related risk factors and marijuana use among adolescents in Argentina, Chile, and Uruguay from 2001 to 2016.Methods: Using cross-sectional surveys from 8th, 10th, and 12th graders and weighted time-varying effect models, we estimated associations between perceived risk (no/low risk versus moderate/great risk) and perceived availability (easy/very easy versus difficult/very difficult/not able to obtain) of marijuana, and any past-month marijuana use.Results: In all countries, marijuana use increased over time and adolescents who perceived no/low risk and easy availability had higher odds of use. In Argentina, the bivariate risk/use association weakened from 2001 (OR = 15.24, 95%CI = 9.63, 24.12) to 2004 [OR = 3.86 (2.72, 5.48)] and strengthened until 2011 [OR = 8.22 (7.56, 10.30)]; the availability/use association strengthened from 2005 [OR = 5.32 (4.05, 6.98)] to 2009 [OR = 20.77 (15.57, 27.70)] and weakened until 2014 [OR = 11.00 (9.11, 13.27)]. In Chile, the risk/use association weakened from 2001 [OR = 7.22 (6.57, 7.95)] to 2015 [OR = 5.58 (4.82, 6.48)]; the availability/use association weakened from 2001 [OR = 5.92 (4.96, 7.06)] to 2015 [OR = 4.10 (3.15, 5.34)]. In Uruguay, the risk/use association weakened from 2003 [OR = 34.22 (22.76, 51.46)] to 2016 [OR = 6.23 (4.96, 7.83)]; the availability/use association weakened from 2005 [OR = 29.13 (13.39, 63.39) to 2007 [OR = 9.42 (3.85, 23.07)], and strengthened until 2016 [OR = 22.68 (12.03, 42.76)].Conclusions: Overall, the association between risk and use weakened in all countries, suggesting risk perceptions became a weaker determinant of marijuana use. Perceived availability remained strongly associated with use and may become an increasingly important driver of use (particularly in Uruguay and Argentina). [ABSTRACT FROM AUTHOR]

Background: In 2013, Uruguay became the first country in the world to legalize recreational cannabis, instituting a non-commercial state regulatory model of production and supply. This study provides the first empirical evidence on its impacts on adolescent use of cannabis and related risks.Methods: We use a generalization of the synthetic control method (SCM) to estimate the impact of legalization in Uruguay on adolescent past year and month cannabis use, perceived availability of cannabis and perceived risk of cannabis use. We compare biennial high school student self-reported survey data from Montevideo and regions in the interior of Uruguay post-legalization (2014-2018) and post initial implementation (2015-2018) to a synthetic counterfactual constructed using a weighted combination of 15 control regions in Chile.Results: We find no evidence of an impact on cannabis use or the perceived risk of use. We find an increase in student perception of cannabis availability (58% observed vs. 51% synthetic control) following legalization.Conclusion: Our findings provide some support for the thesis that Uruguay's state regulatory approach to cannabis supply may minimize the impact of legalization on adolescent cannabis use. At the same time, our study period represents a period of transition: pharmacy access, by far the most popular means of access, was not available until the summer of 2017. Additional study will be important to assess the longer-term impacts of the fully implemented legalization regime on substance use outcomes. [ABSTRACT FROM AUTHOR]

Background: Little is known about recent nonmedical prescription tranquilizer and stimulant use trends in Latin America. We tested whether recent trends among students in three South American countries differed by sex over time.Methods: Three countries independently collected National School Students Survey on Drugs. Students in 8th, 10th, and 12th grades were sampled in Argentina (2007-2014, N = 328,202), Chile (2007-2015, N = 136,379), and Uruguay (2007-2016, N = 32,371). Weighted linear regression models predicted the prevalences and trends over time of past-year nonmedical tranquilizer and stimulant use by country, and tested whether trends differed by sex, adjusting for school type and grade.Results: In Argentina from 2007 to 2014, past-year nonmedical prescription tranquilizer (girls: 2.8 to 2.6%, boys: 2.5 to 2.3%) and stimulant (girls: 1.7 to 1.3%, boys: 1.9 to 1.5%) use trends did not differ by sex. In Chile from 2007 to 2015, nonmedical prescription tranquilizer use trends significantly differed comparing girls (3.9 to 10%) with boys (3.2 to 6.9%); stimulant use trends did not differ comparing girls (1.6 to 2.0%) with boys (2.0 to 1.3%). In Uruguay from 2007 to 2014 and 2014-2016, past-year nonmedical prescription tranquilizer (girls: 5.1 to 6.6%; boys: 2.8 to 4.2%) and stimulant (girls: 1.8 to 0.7%; boys: 1.8 to 0.7%) use trends did not differ by sex.Conclusions: Trends of nonmedical prescription tranquilizer use recently increased in Chile and Uruguay, widening by sex over time in Chile only. The drivers of increasing tranquilizer use among girls in Chile and Uruguay merit further investigation. [ABSTRACT FROM AUTHOR]