Faculty Bibliography

Importance/UNASSIGNED:Over the last 25 years, illicit cannabis use and cannabis use disorders have increased among US adults, and 28 states have passed medical marijuana laws (MML). Little is known about MML and adult illicit cannabis use or cannabis use disorders considered over time. Objective/UNASSIGNED:To present national data on state MML and degree of change in the prevalence of cannabis use and disorders. Design, Participants, and Setting/UNASSIGNED:Differences in the degree of change between those living in MML states and other states were examined using 3 cross-sectional US adult surveys: the National Longitudinal Alcohol Epidemiologic Survey (NLAES; 1991-1992), the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC; 2001-2002), and the National Epidemiologic Survey on Alcohol and Related Conditions-III (NESARC-III; 2012-2013). Early-MML states passed MML between NLAES and NESARC ("earlier period"). Late-MML states passed MML between NESARC and NESARC-III ("later period"). Main Outcomes and Measures/UNASSIGNED:Past-year illicit cannabis use and DSM-IV cannabis use disorder. Results/UNASSIGNED:Overall, from 1991-1992 to 2012-2013, illicit cannabis use increased significantly more in states that passed MML than in other states (1.4-percentage point more; SE, 0.5; P = .004), as did cannabis use disorders (0.7-percentage point more; SE, 0.3; P = .03). In the earlier period, illicit cannabis use and disorders decreased similarly in non-MML states and in California (where prevalence was much higher to start with). In contrast, in remaining early-MML states, the prevalence of use and disorders increased. Remaining early-MML and non-MML states differed significantly for use (by 2.5 percentage points; SE, 0.9; P = .004) and disorder (1.1 percentage points; SE, 0.5; P = .02). In the later period, illicit use increased by the following percentage points: never-MML states, 3.5 (SE, 0.5); California, 5.3 (SE, 1.0); Colorado, 7.0 (SE, 1.6); other early-MML states, 2.6 (SE, 0.9); and late-MML states, 5.1 (SE, 0.8). Compared with never-MML states, increases in use were significantly greater in late-MML states (1.6-percentage point more; SE, 0.6; P = .01), California (1.8-percentage point more; SE, 0.9; P = .04), and Colorado (3.5-percentage point more; SE, 1.5; P = .03). Increases in cannabis use disorder, which was less prevalent, were smaller but followed similar patterns descriptively, with change greater than never-MML states in California (1.0-percentage point more; SE, 0.5; P = .06) and Colorado (1.6-percentage point more; SE, 0.8; P = .04). Conclusions and Relevance/UNASSIGNED:Medical marijuana laws appear to have contributed to increased prevalence of illicit cannabis use and cannabis use disorders. State-specific policy changes may also have played a role. While medical marijuana may help some, cannabis-related health consequences associated with changes in state marijuana laws should receive consideration by health care professionals and the public.

BACKGROUND:Recently, social movements across the world have demanded reforms to education systems and other institutions. Although such movements have affected large numbers of people across multiple countries, we know little about the impacts they have had on population health. We focus on one example: the massive strikes and collective occupation of secondary schools across Chile, which occurred contemporaneously with a large increase in marijuana use among students in this age group. We aimed to evaluate the causal effects that the 2011 Chilean school strikes had on adolescent substance use, including the initiation of marijuana use and the use of alcohol and marijuana. METHODS:School-level, aggregated panel design using data from the National Drug Surveys among Secondary Students from 2005 to 2015 for students in grades 9-12. We used a fixed-effects difference-in-difference model to estimate the effect of school occupations on prevalence of self-reported indicators of drug use. RESULTS:Reported marijuana use doubled between 2009 and 2013 among Chilean adolescents. After controlling for secular trends in outcomes and for school characteristics, there was no evidence of increased marijuana initiation, alcohol and marijuana use, or of an increase in heavy use among adolescents being directly attributable to school strikes and occupations in 2011. CONCLUSIONS:The 2011 Occupy school movement in Chile had no detectable causal effect on substance use among Chilean adolescents. The increase in marijuana use from 2009 to 2013 seems to be part of broader social changes occurring among the school-age population.

OBJECTIVES/OBJECTIVE:To investigate the validity of the apparent downward trend in the national case-fatality rate for gunshot wounds from assault. METHODS:We reanalyzed the estimated annual number of nonfatal firearm injuries the National Electronic Injury Surveillance System reported from 2003 to 2012. We adjusted the estimates for discontinuities created by the substitution of 1 hospital for another in the sample and for a downward trend in the percentage of gunshot injuries classified as "unknown circumstance." Firearm homicide data are from the Centers for Disease Control and Prevention, Web-based Injury Statistics Query and Reporting System. RESULTS:The unadjusted National Electronic Injury Surveillance System estimate increased by 49%, yielding a decline in the case-fatality rate from 25% to 18%. Our adjustments eliminated these trends; the case-fatality rate was 22% in both 2003 and 2012. CONCLUSIONS:With reasonable adjustments, the trend in nonfatal injuries from interpersonal firearms assault tracks the flat trend in firearms homicides, suggesting that there was no increase in firearms violence during this period. The case-fatality rate did not change, and trauma care improvements did not influence the firearms homicide trend.

BACKGROUND:We compare self-reported prevalence of drug use and indicators of data quality from two different response modes (with and without an independent answer sheet for recording responses) in a survey conducted in 2015 among secondary school students. METHODS:Stratified cluster-randomized study conducted among students in grades 8-12 from public, private and subsidized schools in Chile (N=2317 students in 122 classes). Measurements included were: percentage reporting substance use (tobacco, alcohol, marijuana, cocaine, ecstasy); number of inconsistent responses; number of item nonresponses; percentage of extreme reports of drug use; percentage reporting using the nonexistent drug, relevón; and completion times. RESULTS:Compared with those who responded directly in the questionnaire booklet, students who used a separate answer sheet took 17.6 more minutes (95% confidence interval [CI]: 14.4-20.8) to complete the survey and had on average 1.5 more inconsistent responses (95%CI: 0.91-2.14). The prevalence and variance of drug use was higher among those who used an answer sheet for all substances except tobacco; the prevalence ratio (PR) of reported substance use for low-prevalence substances during the past year were: cocaine PR=2.5 (95%CI: 1.6-4.1); ecstasy PR=5.0 (95%CI: 2.4-10.5); relevón PR=4.8 (95%CI: 2.5-9.3). CONCLUSIONS:Using an answer sheet for a self-administered paper-and-pencil survey of drug use among students result in lower quality data and higher reports of drug use. International comparison of adolescent drug use from school-based surveys should be done with caution. The relative ranking of a country could be misleading if different mode of recording answers are used.

Agent-based models (ABMs) have grown in popularity in epidemiologic applications, but the assumptions necessary for valid inference have only partially been articulated. In this issue, Murray et al. (Am J Epidemiol. 2017;186(2):131-142) provided a much-needed analysis of the consequence of some of these assumptions, comparing analysis using an ABM to a similar analysis using the parametric g-formula. In particular, their work focused on the biases that can arise in ABMs that use parameters drawn from distinct populations whose causal structures and baseline outcome risks differ. This demonstration of the quantitative issues that arise in transporting effects between populations has implications not only for ABMs but for all epidemiologic applications, because making use of epidemiologic results requires application beyond a study sample. Broadly, because health arises within complex, dynamic, and hierarchical systems, many research questions cannot be answered statistically without strong assumptions. It will require every tool in our store of methods to properly understand population dynamics if we wish to build an evidence base that is adequate for action. Murray et al.'s results provide insight into these assumptions that epidemiologists can use when selecting a modeling approach.

BACKGROUND:Marijuana use has been decreasing in the past several years among adolescents, though variation in the extent and rate of decrease across racial/ethnic groups is inadequately understood. METHODS:The present study utilized nationally-representative data in Monitoring the Future from 2006 to 2015 to examine trends over time in past 30-day marijuana use. We examine whether differences in trends over time by race and ethnicity also differ by individual-level, school-level, and state-level factors. Sample included 131,351 8th grade students, 137,249 10th grade students, and 123,293 12th grade students; multi-level models and difference-in-differences tests were used. RESULTS:In 10th grade, Black students had a positive linear increase in marijuana use (est=0.04, SE=0.01, p<0.001), and the magnitude of the increase was significantly greater than among non-Hispanic White students (est=0.38, SE=0.009, p<0.001). The increase trend among Black students was greater among those in large class sizes. In 12th grade, all racial ethnic groups except non-Hispanic Whites demonstrated a linear increase in prevalence across time. The magnitude of the increase among Hispanic students was greater among those in urban areas and large class sizes. The magnitude of the increase among Black students was greater in states with a medical marijuana law before 2006 (est=0.06, SE=0.03, p=0.02), among other state-level covariates. CONCLUSION/CONCLUSIONS:Together these results suggest that the next stage of public health approaches to reducing the harms associated with adolescent drug use should attend to shifting demographic patterns of use among adolescents and ensure that services and programmatic approaches to adolescent prevention are applied equitably.