Cannabis and traffic collision risk: findings from a case-crossover study of injured drivers presenting to emergency departments

Risk of motor vehicle collision associated with cannabis and alcohol use among patients presenting for emergency care

BACKGROUND

The objective of this study was to examine the relationship between cannabis and alcohol use and occurrence of motor vehicle collision (MVC) among patients in the emergency department (ED).

METHODS

This was a cross-sectional study of visits to EDs in Denver, CO, Portland, OR, and Sacramento, CA by drivers who were involved in MVCs and presented with injuries (cases) and non-injured drivers (controls) who presented for medical care. We obtained blood samples and measured delta-9-THC and its metabolites. Alcohol levels were determined by breathalyzer or samples taken in the course of clinical care. Participants completed a research-assistant-administered interview consisting of questions about drug and alcohol use prior to their visit, context of use, and past-year drug and alcohol use. Multiple logistic regression was used to estimate the association between MVC and cannabis/alcohol use, adjusted for demographic characteristics. We then stratified participants based on levels of cannabis use and calculated the odds of MVC across these levels, first using self-report and then using blood levels for delta-9-THC in separate models. We conducted a case-crossover analysis, using 7-day look-back data to allow each participant to serve as their own control. Sensitivity analyses examined the influence of usual use patterns and driving in a closed (car, truck, van) versus open (motorcycle, motorbike, all-terrain vehicle) vehicle.

RESULTS

Cannabis alone was not associated with higher odds of MVC, while acute alcohol use alone, and combined use of alcohol and cannabis were both independently associated with higher odds of MVC. Stratifying by level of self-reported or measured cannabis use, higher levels were not associated with higher odds for MVC, with or without co-use of alcohol; in fact, high self-reported acute cannabis use was associated with lower odds of MVC (odds ratio [OR] 0.18, 95% confidence interval [CI] 0.05-0.65). In the case-crossover analysis, alcohol use alone or in combination with cannabis was associated with higher odds of MVC, while cannabis use alone was again associated with decreased odds of MVC.

CONCLUSIONS

Alcohol use alone or in conjunction with cannabis was consistently associated with higer odds for MVC. However, the relationship between measured levels of cannabis and MVC was not as clear. Emphasis on actual driving behaviors and clinical signs of intoxication to determine driving under the influence has the strongest rationale.

Can inhaled cannabis users accurately evaluate impaired driving ability? A randomized controlled trial

Aims

To study the effect of inhaled cannabis on self-assessed predicted driving ability and its relation to reaction times and driving ability on a driving simulator.

Participants and methods

30 healthy male volunteers aged 18-34: 15 chronic (1-2 joints /day) and 15 occasional (1-2 joints/week) consumers. Self-assessed driving confidence (visual analog scale), vigilance (Karolinska), reaction time (mean reciprocal reaction time mRRT, psychomotor vigilance test), driving ability (standard deviation of lane position SDLP on a York driving simulator) and blood concentrations of delta-9-tétrahydrocannabinol (THC) were measured before and repeatedly after controlled inhalation of placebo, 10 mg or 30 mg of THC mixed with tobacco in a cigarette.

Results

Cannabis consumption (at 10 and 30 mg) led to a marked decrease in driving confidence over the first 2 h which remained below baseline at 8 h. Driving confidence was related to THC dose and to THC concentrations in the effective compartment with a low concentration of 0.11 ng/ml for the EC50 and a rapid onset of action (T1/2 37 min). Driving ability and reaction times were reduced by cannabis consumption. Driving confidence was shown to be related to driving ability and reaction times in both chronic and occasional consumers.

Conclusions

Cannabis consumption leads to a rapid reduction in driving confidence which is related to reduced ability on a driving simulator.

Clinical trial registration

ClinicalTrials.gov, identifier: NCT02061020.

Personality, perceptions and behavior: A study of speeding amongst drivers in Victoria, Australia

INTRODUCTION

Road crashes present a serious public health issue. Many people are seriously or fatally injured every year in avoidable crashes. While these crashes can have multiple contributing factors, including road design and condition, vehicle design and condition, the environment and human error, the performance of illegal driving behavior, including speeding, may also play a role. The current study aimed to examine the mediating influence that four potential deterrents (perceptions towards enforcement, crash risk, social norms and disapproval, and negative personal/emotional affect) have between the Big Five personality traits (conscientiousness; extraversion; agreeableness; neuroticism; openness) and expectations to speed.

METHODS

A total of 5,108 drivers in Victoria, Australia completed an online survey in 2019. A mediated regression analysis was used to examine pathways in a conceptual model developed for the study.

RESULTS

The results showed that perceptions towards the four potential deterrents examined did mediate the relationship (either completely or partially) between personality and expectations to speed.

CONCLUSIONS

The results of this study suggest that if interventions to deter illegal driving behavior are to be successful, one factor that could be taken into account is the personality traits of drivers who may be at greatest risk of the performance of illegal driving behaviors.

Alcohol and cannabis use in traffic-related injuries in Mexico City

BACTERKGROUND

There is debate on whether cannabis affects road traffic injuries (RTIs) separately from the effects of alcohol. Our goals are to report the possible increase in risk of an RTI among alcohol and cannabis users by type of exposure (biological, self-reported and combined) and the possible interaction of alcohol and cannabis in patients with an RTI in an emergency department in Mexico City.

METHODS

A case-crossover study with 433 cases of RTI (as a pedestrian, driver or passenger) during the period January-April 2022. A breath sample, an oral sample for cannabis detection and self-reported alcohol and cannabis use 6 hours prior to the RTI and in two control periods were used. We report ORs and 95% CIs from conditional logistic regressions for the case-crossover estimates.

RESULTS

Alcohol alone increased the risk of an RTI (OR=6.02, 95% CI 3.29 to 10.99) for most RTIs, regardless of whether we used information from self-reports or a breath sample in the hazard period. Conversely, cannabis only increased the RTI when we added information in the hazard period from self-reports or oral samples. Nevertheless, this increase in risk disappeared (OR=2.06, 95% CI 0.90 to 4.70) among those who only used cannabis. We also found no evidence of interaction between alcohol and cannabis in the risk of an RTI.

CONCLUSIONS

Alcohol is the most commonly used substance in Mexico and a high-risk factor for RTI in Mexico City. Although cannabis alone was not associated with an RTI, continuous monitoring of its effects is required.

A systematic review of factors associated with illegal drug driving

Drug driving is a serious problem worldwide that can increase the risk of road crashes. This systematic review seeks to identify factors associated with drug driving (i.e., driving after consuming drugs other than alcohol) to highlight gaps in existing knowledge and inform the design of more effective countermeasures. A search of the literature was conducted for the period January 1, 2005 to July 31, 2021 using six different databases. The search protocol followed PRISMA guidelines and was registered in PROSPERO (#CRD42021234616). Studies that met inclusion criteria compared drug drivers with either non-drug drivers, alcohol-only drivers or drug drivers from an earlier time period, to identify factors specifically associated with drug driving, rather than common to all drivers. Two hundred and nineteen publications met the inclusion criteria and were included within the review. Based on the findings, a logic model was developed that presents the factors associated with drug driving. Various sociodemographic, psychosocial and legal factors emerged as the main factors associated with illegal drug driving. At the sociodemographic and psychological levels, drug drivers were more likely to be single, young males who often drive after using cannabis and who score high on sensation-seeking and impulsivity scales. The key social factor found to be associated with drug driving was peer acceptance/disapproval of the behaviour. At the legal level, the review suggested that the effectiveness of current enforcement approaches to drug driving vary among jurisdictions around the world due to differences in the level of perceived certainty of apprehension and the chances of punishment avoidance. Future research into the anticipated and actual rewards for drug driving is needed to inform the development of more effective countermeasures.

Driving under the influence of drugs: Correlation between blood psychoactive drug concentrations and cognitive impairment. A narrative review taking into account forensic issues

Driving under the influence of alcohol has been shown to increase the risk of involvement in road traffic collisions (RTCs) however, less is known about the effects of illicit drugs, and a clear correlation between drug concentrations and RTC risk is still debated. The goal of this narrative review is to assess the current literature regarding the most detected psychoactive drugs in RTC (ethanol, amphetamines, cannabis, opioids and cocaine), in relation to driving performance. Evidence on impaired driving due to psychoactive substances, forensic issues relating to the assessment of the impact of drugs, blood cut-off values proposed to date as well as scientific basis for proposed legislative limits are discussed. At present there is no unequivocal evidence demonstrating a clear dose/concentration dependent impairment in many substances. Per se and zero tolerance approaches seem to have negative effect on drugged driving fatalities. However, the weight of these approaches needs further investigation.

Cannabis presentations to the emergency department after MVC in the era of legalization for recreational use

INTRODUCTION

The objectives of this study were to examine cannabis and alcohol use among injured patients presenting to emergency departments (ED) in cannabis-legal states to capture an expanded profile of cannabis use and evaluate differences in motor-vehicle collision (MVC) characteristics among those using cannabis alone and in combination with alcohol.

METHODS

This was a cross-sectional study of ED visits by drivers in MVC who presented to one of three study sites. Event-related and usual drug and alcohol use information were obtained using a detailed interviewer-administered computerized questionnaire. We also obtained data from blood and breathalyzer tests and the electronic medical record. We examined frequency and types of acute and past-year cannabis and alcohol use and crash mechanisms and characteristics. Our primary method of determining substance use was self-report; we used biosamples secondarily.

RESULTS

Eight percent of drivers reported cannabis use in the 8 h prior to MVC, alone or in combination with alcohol; however, a higher proportion (18%) were positive by biosample. High-risk crash features were common in MVCs associated with cannabis, as they were for alcohol use and co-use of cannabis and alcohol; however, patients injured seriously enough to require admission were less likely to report cannabis use (7% vs. 9%) and more likely to report alcohol use (16% vs. 10%).

CONCLUSIONS

Cannabis use was common among patients presenting after MVC in this sample of cannabis-legal states. Practical Applications: Differences between self-report and biosample data for cannabis and alcohol use were significant and supports the need to use both means of assessing acute use.

Preliminary Eye-Tracking Data as a Nonintrusive Marker for Blood Δ-9-Tetrahydrocannabinol Concentration and Drugged Driving

Background: Cannabis is one of the drugs most often found in drivers involved in serious motor vehicle collisions. Validity and reliability of roadside cannabis detection strategies are questioned. This pilot study aimed to investigate the relationship between eye characteristics and cannabis effects in simulated driving to inform potential development of an alternative detection strategy. Materials and Methods: Multimodal data, including blood samples, eye-tracking recordings, and driving performance data, were acquired from 10 participants during a prolonged single-session driving simulator experiment. The study session included a baseline driving trial before cannabis exposure and seven trials at various times over ∼5 h after exposure. The multidimensional eye-tracking recording from each driving trial for each participant was segmented into nonoverlapping epochs (time windows); 34 features were extracted from each epoch. Blood Δ-9-tetrahydrocannabinol (THC) concentration, standard deviation of lateral position (SDLP), and mean vehicle speed were target variables. The cross-correlation between the temporal profile of each eye-tracking feature and target variable was assessed and a nonlinear regression analysis evaluated temporal trend of features following cannabis exposure. Results: Mean pupil diameter (r=0.81-0.86) and gaze pitch angle standard deviation (r=0.79-0.87) were significantly correlated with blood THC concentration (p<0.01) for all epoch lengths. For driving performance variables, saccade-related features were among those showing the most significant correlation (r=0.61-0.83, p<0.05). Epoch length significantly affected correlations between eye-tracking features and speed (p<0.05), but not SDLP or blood THC concentration (p>0.1). Temporal trend analysis of eye-tracking features after cannabis also showed a significant increasing trend (p<0.01) in saccade-related features, including velocity, scanpath, and duration, as the influence of cannabis decreased by time. A decreasing trend was observed for fixation percentage and mean pupil diameter. Due to the lack of placebo control in this study, these results are considered preliminary. Conclusion: Specific eye characteristics could potentially be used as nonintrusive markers of THC presence and driving-related effects of cannabis. clinicaltrials.gov (NCT03813602).

Driving after marijuana use among U.S. adolescents: Prevalence profiles and related behaviors

OBJECTIVES

The interplay between marijuana legislation, perceptions of risks associated with marijuana use, and marijuana-related risk behaviors is an ever changing and complex issue. Marijuana impaired driving is of concern as legalization continues to expand in the United States. While driving after using marijuana has been shown to be prevalent among adults, little research has examined the behavior in adolescents. The aim of the present study was to examine the prevalence of driving after using marijuana among U.S. adolescents, with an examination of the relationship to age of marijuana initiation and marijuana usage patterns.

METHODS

We analyzed data from the 2017 Youth Risk Behavior Survey, a nationally representative sample of high schools students in the U.S. The sample was current marijuana users, defined as past 30 day use. Driving after using marijuana was the main outcome variable, with analyses examining the association between the outcome and age of initiation and patterns of use. Prevalence ratios were obtained by modeling Poisson regression to examine factors associated with driving under the influence of marijuana.

RESULTS

Nearly half of all marijuana users reported driving after use during the past 30 days, and did not differ between males and females. Prevalence of driving after using marijuana was significantly higher among heavy users (PR = 2.8; 95% CI 2.1-3.6). A higher prevalence of driving after drinking alcohol (PR = 1.7; 95% CI 1.5-1.9) was also found among those who had driven after using marijuana.

CONCLUSIONS

Among adolescent marijuana users, the prevalence of driving after using marijuana was high. Enhanced surveillance, prevention, and control measures are necessary to mitigate the negative impacts of marijuana consumption and related behaviors.

Steering clear: Traffic violations among emerging adults who engage in habitual or casual cannabis use

While some research has shown that cannabis use can impair driving ability, evidence to the degree and impact of impairment are lacking. This study examined the association between habitual or casual cannabis use and past-year traffic violations among emerging adults (EAs). Data come from the 2012 Canadian Community Health Survey-Mental Health. Respondents (n = 5630) were categorized as: early (15-19 y), middle (20-24 y), and late (25-29 y) EAs. Traffic violations were measured using self-report and cannabis use was measured using the WHO Composite International Diagnostic Interview. The prevalence of traffic violations was higher for males (19.2 %) vs females (9.9 %) and middle (16.2 %) and late (19.4 %) EAs vs early (8.8 %) EAs. The odds of reporting traffic violations were higher for EAs who engaged in habitual [OR = 1.77 (1.17-2.67)] or casual [OR = 1.79 (1.27-2.51)] cannabis use when compared to non-users. Age moderated the association such that higher odds of traffic violations were reported in early EAs who were casual cannabis users and middle EAs who were habitual or casual cannabis users when compared to non-users. Use of other drugs was also a moderator-in the absence vs. presence of other drug use, odds of traffic violations were higher in those who engaged in either habitual or casual use of cannabis. When accounting for the moderating effects of age and drug use, habitual and casual cannabis use resulted in increased odds of a traffic violation. Future research is warranted to explore the robustness of our findings.

Modeling the system of beliefs that influence driving under the influence of cannabis (DUIC) in Washington State

Cannabis use is increasing in the U.S. Driving under the influence of cannabis (DUIC) may be increasing as well potentially resulting in fatal and serious injury crashes. The purpose of this article is to explore the belief system associated with driving under the influence of cannabis (DUIC) using structural equation modeling (SEM). A sample (n = 2,084) of surveys collected from adults in the U.S. was analyzed using SEM to reveal the latent structure of the belief system associated with DUIC. The results of this analysis indicated that reported DUIC behavior (frequency and recency) was predicted by willingness that influenced intention. Willingness and intention were directly influenced by control beliefs, attitudes, norms, and attitudes (prototype image) toward people who never DUIC. Intention was also influenced by attitudes toward people who do DUIC. Intention had a stronger influence on DUIC than willingness alone. These components were influenced by underlying behavioral, normative, and control beliefs. Thus, strategies that can change these beliefs may also reduce DUIC.

Early, Chronic, and Acute Cannabis Exposure and Their Relationship With Cognitive and Behavioral Harms

Background: Cannabis is the third most consumed drug worldwide. Thus, healthcare providers should be able to identify users who are in need for an intervention. This study aims to explore the relationship of acute, chronic, and early exposure (AE, CE, and EE) to cannabis with cognitive and behavioral harms (CBH), as a first step toward defining risky cannabis use criteria. Methods: Adults living in Spain who used cannabis at least once during the last year answered an online survey about cannabis use and health-related harms. Cannabis use was assessed in five dimensions: quantity on use days during the last 30 days (AE), frequency of use in the last month (AE), years of regular use (YRCU) (CE), age of first use (AOf) (EE), and age of onset of regular use (AOr) (EE). CBH indicators included validated instruments and custom-made items. Pearson correlations were calculated for continuous variables, and Student's t-tests for independent samples were calculated for categorical variables. Effect sizes were calculated for each of the five dimensions of use (Cohen's d or r Pearson correlation) and harm outcome. Classification and Regression Trees (CART) analyses were performed for those dependent variables (harms) significantly associated with at least two dimensions of cannabis use patterns. Lastly, logistic binary analyses were conducted for each harm outcome. Results: The mean age of participants was 26.2 years old [standard deviation (SD) 8.5]. Out of 2,124 respondents, 1,606 (75.6%) reported at least one harm outcome (mean 1.8 and SD 1.5). In our sample, using cannabis on 3 out of 4 days was associated with an 8-fold probability of scoring 4+ on the Severity Dependence Scale (OR 8.33, 95% CI 4.91-14.16, p <0.001), which is indicative of a cannabis use disorder. Also, a start of regular cannabis use before the age of 25 combined with using cannabis at least once per month was associated with a higher probability of risky alcohol use (OR 1.33, 95% CI 1.12-1.57, p = 0.001). Besides, a start of regular cannabis use before the age of 18 combined with a period of regular use of at least 7.5 years was associated with a higher probability of reporting a motor vehicle accident (OR 1.81, 95% CI 1.41-2.32, p < 0.0001). Results were ambiguous regarding the role that age of first use and milligrams of THC per day of use might play regarding cannabis-related harms. Conclusions: The relationship among AE, CE, and EE with CBH indicators is a complex phenomenon that deserves further studies. The pattern of cannabis use should be carefully and widely evaluated-(not just including frequency but also other dimensions of pattern of use)-in research (preferably in longitudinal studies) to assess cannabis-related harms.

Cannabis Use and Car Crashes: A Review

In this review, state-of-the-art evidence on the relationship between cannabis use, traffic crash risks, and driving safety were analyzed. Systematic reviews, meta-analyses, and other relevant papers published within the last decade were systematically searched and synthesized. Findings show that meta-analyses and culpability studies consistently indicate a slightly but significantly increased risk of crashes after acute cannabis use. These risks vary across included study type, crash severity, and method of substance application and measurement. Some studies show a significant correlation between high THC blood concentrations and car crash risk. Most studies do not support this relationship at lower THC concentrations. However, no scientifically supported clear cut-off concentration can be derived from these results. Further research is needed to determine dose-response effects on driving skills combined with measures of neuropsychological functioning related to driving skills and crash risk.

Illicit Cannabis Usage as a Management Strategy in New Zealand Women with Endometriosis: An Online Survey

Background: Endometriosis affects around 10% of women worldwide. Many women with endometriosis struggle with finding adequate pain management, and data from other countries suggest that women use cannabis, either legal or illicit, to help manage their endometriosis symptoms. The aim of this study was to determine use of cannabis where endometriosis was self-identified as a condition that was being treated with cannabis, as well as the impact of cannabis use on the usage on other pharmaceuticals. Materials and Methods: A cross-sectional online survey of those using cannabis for health-related conditions run between May and July 2019. This article reports on the subset of this larger data set for those reporting they had a diagnosis of endometriosis and/or polycystic ovary syndrome. Data were collected on demographics, modes of cannabis administration, symptoms treated, changes in pharmaceutical usage, and adverse events. Results: Two hundred thirteen valid responses were analyzed. Mean age of respondents was 32 years and 79.8% were current cannabis users. The most common outcomes that cannabis was used for were to improve pain relief (95.5%) and to improve sleep (95.5%). Respondents reported that their symptom was "much better" for pain (81%), sleep (79%), and nausea or vomiting (61%). Over three-quarters (81.4%) indicated cannabis had reduced their normal medication usage. Over half (59%) were able to completely stop a medication, most commonly (66%) analgesics. Opioids (40%) were the most common class of analgesic stopped. Conclusions: Cannabis is reported as an effective intervention for pain and other endometriosis symptoms with potential substitution effects on opioid usage.

Cannabis and work: Need for more research

Cannabis sativa is one of the oldest and most widely used plants in the world with a variety of industrial, medical, and nonmedical applications. Despite its long history, cannabis-derived products remain a source of controversy across the fields of medicine, law, and occupational safety and health. More favorable public attitudes about cannabis in the US have resulted in greater access to cannabis through legalization by states, leading to more consumption by workers. As more states adopt cannabis access laws, and as more workers choose to consume cannabis products, the implications for existing workplace policies, programs, and practices become more salient. Past workplace practices were grounded in a time when cannabis consumption was always viewed as problematic, considered a moral failing, and was universally illegal. Shifting cultural views and the changing legal status of cannabis indicate a need for research into the implications and challenges relating to cannabis and work. This commentary suggests research needs in the following areas: (a) data about industries and occupations where cannabis consumption among workers is most prevalent; (b) adverse health consequences of cannabis consumption among workers; (c) workplace supported recovery programs; (d) hazards to workers in the emerging cannabis industry; (e) relationship between cannabis consumption and occupational injuries; (f) ways to assess performance deficits and impairment from cannabis consumption; (g) consumption of synthetic cannabinoids to evade detection by drug testing; (h) cannabis consumption and its effect on occupational driving; and (i) ways to craft workplace policies and practices that take into consideration conflicting state and federal laws pertaining to cannabis.

Prescription medication use as a risk factor for motor vehicle collisions: a responsibility study

INTRODUCTION

Previous studies on the effect of prescription medications on MVCs are sparse, not readily applicable to real-world driving and/or subject to strong selection bias. This study examines whether the presence of prescription medication in drivers' blood is associated with being responsible for MVC.

METHODS

This modified case-control study with responsibility analysis compares MVC responsibility rates among drivers with detectable levels of six classes of prescription medications (anticonvulsants, antidepressants, antihistamines, antipsychotics, benzodiazepines, opioids) versus those without. Data were collected between January 2010 and July 2016 from emergency departments in British Columbia, Canada. Collision responsibility was assessed using a validated and automated scoring of police collision reports. Multivariable logistic regression was used to determine OR of responsibility (analysed in 2018-2019).

RESULTS

Unadjusted regression models show a significant association between anticonvulsants (OR 1.92; 95% CI 1.20 to 3.09; p=0.007), antipsychotics (OR 5.00; 95% CI 1.16 to 21.63; p=0.03) and benzodiazepines (OR 2.99; 95% CI 1.56 to 5.75; p=0.001) with collision responsibility. Fully adjusted models show a significant association between benzodiazepines with collision responsibility (aOR 2.29; 95% CI 1.16 to 4.53; p=0.02) after controlling for driver characteristics, blood alcohol and Δ-9-tetrahydrocannabinol concentrations, and the presence of other prescription medications. Antidepressants, antihistamines and opioids exhibited no significant associations.

CONCLUSION

There is a moderate increase in the risk of a responsible collision among drivers with detectable levels of benzodiazepines in blood. Physicians and pharmacists should consider collision risk when prescribing or dispensing benzodiazepines. Public education about benzodiazepine use and driving and change to traffic policy and enforcement measures are warranted.

Recreational cannabis use impairs driving performance in the absence of acute intoxication

BACKGROUND

Across the nation, growing numbers of individuals are exploring the use of cannabis for medical or recreational purposes, and the proportion of cannabis-positive drivers involved in fatal crashes increased from 8 percent in 2013 to 17 percent in 2014, raising concerns about the impact of cannabis use on driving. Previous studies have demonstrated that cannabis use is associated with impaired driving performance, but thus far, research has primarily focused on the effects of acute intoxication.

METHODS

The current study assessed the potential impact of cannabis use on driving performance using a customized driving simulator in non-intoxicated, heavy, recreational cannabis users and healthy controls (HCs) without a history of cannabis use.

RESULTS

Overall, cannabis users demonstrated impaired driving relative to HC participants with increased accidents, speed, and lateral movement, and reduced rule-following. Interestingly, however, when cannabis users were divided into groups based on age of onset of regular cannabis use, significant driving impairment was detected and completely localized to those with early onset (onset before age 16) relative to the late onset group (onset ≥16 years old). Further, covariate analyses suggest that impulsivity had a significant impact on performance differences.

CONCLUSIONS

Chronic, heavy, recreational cannabis use was associated with worse driving performance in non-intoxicated drivers, and earlier onset of use was associated with greater impairment. These results may be related to other factors associated with early exposure such as increased impulsivity.

Marijuana and alcohol use among injured drivers evaluated at level I trauma centers in Arizona, 2008-2014

BACKGROUND

We examined marijuana and alcohol use trends among drivers aged ≥16 years evaluated at Level I trauma centers before and after Arizona legalized medical marijuana in April 2011.

METHODS

We conducted interrupted time series (ITS) analysis of urine drug screens for marijuana metabolites and blood alcohol concentration (BAC) data from the 2008-2014 Arizona State Trauma Registry.

RESULTS

Among 30,083 injured drivers, 14,710 had marijuana test results, and 2590 were positive for marijuana; of these, 1087 (42%) also tested positive for alcohol. Among 23,186 drivers with BAC results, 5266 exceeded the legal limit for their age. Compared with prelaw trends (models if law had not been enacted), postlaw models showed small but significant annual increases in the proportions of drivers testing positive for either substance. By the end of 2014, the proportion of drivers testing positive for marijuana was 9.6% versus a projected 5.6% if the law had not been enacted, and the proportion of drivers with illegal BACs was 15.7% versus a projected 8.2%. When ITS was restricted to only substance-tested drivers, no significant differences were detected.

CONCLUSIONS

Despite the small annual postlaw increases in the proportion of marijuana-positive drivers compared with the prelaw trend, alcohol-impaired driving remains a more prevalent threat to road safety in Arizona.

Does Starting to Smoke Cigars Trigger Onset of Cannabis Blunt Smoking?

Introduction

Among United States teens during the 1990s, increasing cigar use coincided with increasing use of tobacco cigar shells filled with cannabis, called "blunts." Cigar smokers are more likely to use cannabis, and we hypothesized that starting to smoke cigars might be a probabilistic "trigger" of blunt smoking. We turned to the case-crossover approach to evaluate this hypothesis.

Methods

Within US National Surveys on Drug Use and Health, 2009-2013, we identified a nationally representative sample of newly incident blunt smokers aged 12- to 21-years-old (n = 4868) and compared month-of-onsets for smoking of cigars and blunts. Using the subjects-as-their-own-controls case-crossover design, we specified the first month prior to blunt use as a "hazard interval" and the second month prior to blunt use as a "control interval." We used Mantel-Haenszel (MH) estimators to estimate the matched-pairs odds ratio (OR).

Results

The MH OR estimate was 1.7 (95% CI = 1.3, 2.3), with excess odds of cigar onsets during the hazard interval relative to the control interval. Two alternative control interval specifications yielded congruent estimates (OR = 2.7 and 2.9, respectively).

Conclusions

A short interval right after starting to smoke cigars may be one of increased risk of starting to smoke blunts. We discuss cigar, cigarillo, and "blunt wraps" control approaches that might reduce both tobacco and cannabis-related harms.

Implications

If this evidence is correct, increased market-targeting to promote youthful cigar and cigarillo smoking might be followed by increased rates of blunt smoking in a vulnerable population. As noted by others, enhanced risk of smoking-attributable harms might be a consequence of mixed tobacco-cannabis formulations.

The relative risk of motor vehicle collision on cannabis celebration day in Great Britain

Cannabis celebration day, also known as "420 day", takes place at 4:20pm on April 20 every year. The objective of this paper is to study whether there is an increase in road traffic collisions in Great Britain on that day. We used daily car crash data resulting in death or injury from all 51 local police forces covering Great Britain over the period 2011-2015. We compared crashes from 4:20pm onwards on April 20 to control days on the same day of the week in the preceding and succeeding two weeks, using panel data econometric models. On the average cannabis celebration day in Britain, there were an additional 23 police-reported collisions compared to control days, corresponding to a 17.9% increase in the relative risk of collision.

Driving Under the Influence of Cannabis: A Framework for Future Policy

Marijuana is the most widely consumed illicit substance in the United States, and an increasing number of states have legalized it for both medicinal and recreational purposes. As it becomes more readily available, there will be a concurrent rise in the number of users and, consequently, the number of motor vehicle operators driving under the influence. This article examines the cognitive and psychomotor effects of cannabis, as well as current policy concerning driving under the influence of drugs. The authors performed a MEDLINE search on the epidemiology of cannabis use, its cognitive and psychomotor effects, and policies regarding driving under the influence of drugs. Twenty-eight epidemiological studies, 16 acute cognitive and psychomotor studies, 8 chronic cognitive and psychomotor studies, and pertinent state and federal laws and policies were reviewed. These search results revealed that marijuana use is associated with significant cognitive and psychomotor effects. In addition, the legalization of marijuana varies from state to state, as do the laws pertaining to driving under the influence of drugs. Marijuana is a commonly found illicit substance in motor vehicle operators driving under the influence of drugs. Current evidence shows that blood levels of tetrahydrocannabinol do not correlate well with the level of impairment. In addition, although acute infrequent use of cannabis typically leads to cognitive and psychomotor impairment, this is not consistently the case for chronic heavy use. To establish the framework for driving under the influence of cannabis policy, we must review the current published evidence and examine existing policy at state and federal levels.

Exploring perceptions among people who drive after cannabis use: Collision risk, comparative optimism and normative influence

INTRODUCTION AND AIMS

While the perceived risks of driving under the influence of cannabis (DUIC) have been a focus of recent drug-driving research, relevant concepts from the social cognition literature have rarely been applied to inform understanding of DUIC. This study aims to expand knowledge of perceived collision risk and social influences associated with DUIC and driving after other substance use.

DESIGN AND METHODS

Semi-structured interviews were conducted with 20 participants of a remedial program for impaired drivers. Thematic analysis began with two independent coders. Early discussion of emergent themes resulted in the identification of applicable social cognition concepts, resulting in selective coding and interpretation.

RESULTS

Many participants identified DUIC as less risky than driving under the influence of alcohol or other drugs. Mixed perceptions regarding the dangerousness of DUIC were expressed, with some participants denying increased collision risk except among novice cannabis users. Comparative optimism bias was also expressed by participants who perceived themselves as less likely than others to be involved in a collision when DUIC. In view of normative influence, friends were generally seen as more accepting of DUIC than family, and there were indications that the opinions of others who use cannabis were regarded as more credible than the opinions of those who do not use the drug.

DISCUSSION AND CONCLUSIONS

Comparative optimism bias and normative influence may contribute to perceived risks associated with DUIC and may, therefore, be useful concepts to employ to increase the effectiveness of public health and road safety initiatives.

The impact of recreational marijuana commercialization on traumatic injury

BACKGROUND

The medical legalization of marijuana has been shown to result in an increased risk of motor vehicle injuries. In Colorado, commercialization of recreational marijuana (initiation of retail sales) occurred on January 1, 2014, resulting in the rapid proliferation of its availability. The objective of this study was to determine whether the proportion of injured patients testing positive for marijuana and other drugs changed two years before and two years after commercialization of recreational marijuana in Colorado.

METHODS

This retrospective multi-institutional cohort study included all patients admitted with a traumatic injury to six trauma centers (three centers in Colorado and three centers in states without permissive marijuana laws) from 2012 to 2015. The primary outcome was the rate (%) of a positive urine drug screen (UDS) for marijuana. Generalized linear regression models were used to examine the rate of change over time in the pre-commercialization period relative to the post- commercialization period (via an interaction effect), separately for states with and without recreational marijuana legalization.

RESULTS

There were 40,591 trauma admissions. In Colorado, the rate of marijuana detected with UDS decreased over time pre-commercialization; this trend reversed post-commercialization, when marijuana detection rates increased significantly over time (interaction p = 0.004). At non-Colorado hospitals, the rate over time of marijuana detection was significantly reduced post-commercialization relative to the pre-commercialization period (p <  0.001).

CONCLUSION

There was an overall increased rate over time of marijuana detected among trauma patients at Colorado hospitals but not at non-Colorado hospitals, suggesting an increased use of marijuana or an increased risk of injury while using marijuana following the commercialization of recreational marijuana in Colorado.

Alcohol and marijuana use among young injured drivers in Arizona, 2008-2014

OBJECTIVE

We examined alcohol and marijuana use among injured drivers aged 16-20 years evaluated at Arizona level 1 trauma centers during 2008-2014.

METHODS

Using data from the Arizona State Trauma Registry, we conducted a descriptive analysis of blood alcohol concentration (BAC) and qualitative test results (positive or negative) for delta-9-tetrahydrocannabinol (THC) by year of age, sex, race, ethnicity, injury severity, seat belt use, motorcycle helmet use, and type of vehicle driven. To explore compliance with Arizona's motorcycle helmet law requiring helmet use for riders <18 years old, we examined helmet use by age.

RESULTS

Data on 5,069 injured young drivers were analyzed; the annual number of injured drivers declined by 41% during the 7-year study period. Among the 76% (n = 3,849) of drivers with BAC results, 19% tested positive, indicating that at least 15% of all drivers had positive BACs. Eighty-two percent of the BAC-positive drivers had BACs ≥0.08 g/dL, the illegal threshold for drivers aged ≥21 years. Among the 49% (n = 2,476) of drivers with THC results, 30% tested positive, indicating that at least 14% of all drivers were THC-positive. American Indians and blacks had the highest proportion of THC-tested drivers with positive THC results (38%). In addition, 28% of tested American Indians had positive results for both substances, more than twice the proportion seen in all other race or ethnic groups. Crude prevalence ratios suggested that drivers who tested positive for alcohol or THC were less likely than those who tested negative to wear a helmet or seat belt, further increasing their injury risk. Helmet use among motorcyclists was lower among 16- and 17-year-old riders compared to 18- to 20-year-olds, despite Arizona's motorcycle helmet law requiring riders aged <18 years to wear a helmet.

CONCLUSIONS

About 1 in 4 injured drivers aged 16-20 years tested positive for alcohol, THC, or both substances. Most drivers with positive BACs were legally intoxicated (BAC ≥0.08 g/dL). All substance-using young drivers in this study were candidates for substance abuse screening and possible referral to treatment. Broader enforcement of existing laws targeting underage access to alcohol and alcohol-impaired driving could further reduce injuries among young Arizona drivers. To further reduce crash-related injuries and fatalities among all road users, the state could consider implementing a primary enforcement seat belt law and a universal motorcycle helmet law.

The prevalence and correlates of texting while driving among a population-based sample of Ontario students

OBJECTIVE

Texting while driving (TWD) has a deleterious impact on driving performance and may pose a significant challenge to traffic safety. This challenge may be particularly relevant for young and inexperienced drivers. This study examined the prevalence and risk factors of writing text messages or emails while driving during the past 12 months.

METHOD

This study analyzed a subpopulation of 1,133 licensed students 16 years of age or older from the 2013 Ontario Student Drug Use Survey (OSDUHS), a population-based survey of students in Ontario, Canada.

RESULTS

Our results indicate that 36% of licensed drivers reported writing a text message while driving during the past 12 months; of those who did, 56% reported doing so 4 or more times. Graduated licensing was the strongest factor predicting TWD. Compared to students with the more restrictive G1 license, students with a G2 or full license were 9.4 times more likely to report TWD after controlling for the effect of all other factors. Older students, white students, and students attending school in urban centers were more likely to report TWD, and the amount of time spent on social media sites, being a passenger with a driver using substances, and past-year collisions were also significantly associated with TWD. Gender differences and participation in driver education training were not associated with TWD.

CONCLUSIONS

This research demonstrates that TWD is an extremely common behavior among licensed student drivers in Ontario, particularly among those who have passed the first stage of graduated licensing. TWD is associated with other risky driving behaviors and outcomes, and the findings from this study underscore the need to better understand the harms associated with this behavior.

Challenges and common weaknesses in case-control studies on drug use and road traffic injury based on drug testing of biological samples

PURPOSE

To determine and discuss common weaknesses and errors in case-control studies on the association between drug use and road traffic crash injury among drivers and recommend improvements for future studies.

METHODS

A search for case-control studies published between 2000 and 2016 was performed using PubMed and other databases in addition to manual search. The used methodologies were compared with requirements and recommendations for case-control studies as well as current knowledge on the interpretation of drug concentrations in biological samples.

RESULTS

Seventeen studies were identified. The major difficulties in the studies were related to likely selection bias, information bias, and confounding. In some studies, the definition of drug exposure was different for controls than for cases, generating potentially serious errors in the odds ratio estimations. Other weaknesses include lacking explanation of the assessment of drug exposure, missing covariates, lacking description of statistical methods, and lack of discussion of bias and confounding.

CONCLUSIONS

Many of the observed challenges and weaknesses can be overcome or reduced. Recommendations for future studies are presented.

Marijuana Use Among Adults 50 Years or Older in the 21st Century

Background: Marijuana is the most commonly used illicit drug among older adults. As an older population grows in the United States that has a tolerant attitude toward marijuana use, the dynamics of marijuana use and the effects of marijuana on personal, social, and health outcomes among older adults require attention. Objectives: This review summarizes epidemiological literature on marijuana use among older adults. Method: A literature search was conducted using PubMed, AgeLine, and an online search engine from January 2000 to December 2017, resulting in 18 articles. Results: The greatest increase in marijuana use was observed among those in the older adult population 50 years or older, and those 65 years or older had the greatest increase in marijuana use in the older adult population. Common correlates of marijuana use among those in the older population included being male, being unmarried, having multiple chronic diseases, having psychological stress, and using other substances such as alcohol, tobacco, other illicit drugs, and prescription drugs. Conclusion: The increased use of marijuana in older populations requires surveillance and additional research to understand the use and effects of marijuana in older populations to avoid negative health outcomes.

Medical Marijuana Legalization and Marijuana Use Among Youth in Oregon

While the legalization of marijuana for medical and recreational use has raised concerns about potential influences on marijuana use and beliefs among youth, few empirical studies have addressed this issue. We examined the association between medical marijuana patients and licensed growers per 1000 population in 32 Oregon counties from 2006 to 2015, and marijuana use among youth over the same period. We obtained data on registered medical marijuana patients and licensed growers from the Oregon Medical Marijuana Program and we obtained data on youth marijuana use, perceived parental disapproval, and demographic characteristics from the Oregon Healthy Teens Survey. Across 32 Oregon counties, the mean rate of marijuana patients per 1000 population increased from 2.9 in 2006 to 18.3 in 2015, whereas the grower rate increased from 3.8 to 11.9. Results of multi-level analyses indicated significant positive associations between rates of marijuana patients and growers per 1000 population and the prevalence of past 30-day marijuana use, controlling for youth demographic characteristics. The marijuana patient and grower rates were also inversely associated with parental disapproval of marijuana use, which decreased from 2006 to 2015 and acted as a mediator. These findings suggest that a greater number of registered marijuana patients and growers per 1000 population in Oregon counties was associated with a higher prevalence of marijuana use among youth from 2006 to 2015, and that this relationship was partially attributable to perceived norms favorable towards marijuana use.

The Association of Unfavorable Traffic Events and Cannabis Usage: A Meta-Analysis

Background: In the last years were published many epidemiological articles aiming to link driving under the influence of cannabis (DUIC) with the risk of various unfavorable traffic events (UTEs), with sometimes contradictory results.

Aim: The primary objective of this study was to analyze whether there is a significant association between DUIC and UTEs.

Materials and Methods: We used two meta-analytical methods to assess the statistical significance of the effect size: random-effects model and inverse variance heterogeneity model.

Results: Twenty-four studies were included in the meta-analysis. We obtained significant increases in the effect size for DUIC tested through blood analysis, with an odds ratio (OR) of 1.97 and a confidence interval (CI) between 1.35 and 2.87; death as an outcome, with an OR of 1.56 and a CI between 1.16 and 2.09; and case–control as the type of study, with an OR of 1.99 and a CI between 1.05 and 3.80. Publication bias was very high.

Conclusion: Our analysis suggests that the overall effect size for DUIC on UTEs is not statistically significant, but there are significant differences obtained through subgroup analysis. This result might be caused by either methodological flaws (which are often encountered in articles on this topic), the indiscriminate employment of the term “cannabis use,” or an actual absence of an adverse effect. When a driver is found, in traffic, with a positive reaction suggesting cannabis use, the result should be corroborated by either objective data regarding marijuana usage (like blood analyses, with clear cut-off values), or a clinical assessment of the impairment, before establishing his/her fitness to drive.

Cannabis Use Has Negligible Effects Following Severe Traumatic Injury

Nearly half of all states have legalized medical marijuana or recreational-use marijuana. As more states move toward legalization, the effects on injured patients must be evaluated. This study sought to determine effects of cannabis positivity at the time of severe injury on hospital outcomes compared with individuals negative for illicit substances and those who were users of other illicit substances. A Level I trauma center performed a retrospective chart review covering subjects over a 2-year period with toxicology performed and an Injury Severity Score (ISS) of more than 16. These individuals were divided into the negative and positive toxicology groups, further divided into the marijuana-only, other drugs-only, and mixed-use groups. Differences in presenting characteristics, hospital length of stay, intensive care unit (ICU) stays, ventilator days, and death were compared. A total of 8,441 subjects presented during the study period; 2,134 (25%) of these had toxicology performed; 843 (40%) had an ISS of more than 16, with 347 having negative tests (NEG); 70 (8.3%) substance users tested positive only for marijuana (MO), 323 (38.3%) for other drugs-only, excluding marijuana (OD), and 103 (12.2%) subjects showed positivity for mixed-use (MU). The ISS was similar for all groups. No differences were identified in Glasgow Coma Scale (GCS), ventilator days, blood administration, or ICU/hospital length of stay when comparing the MO group with the NEG group. Significant differences occurred between the OD group and the NEG/MO/MU groups for GCS, ICU length of stay, and hospital charges. Cannabis users suffering from severe injury demonstrated no detrimental outcomes in this study compared with nondrug users.

Patterns of facial trauma before and after legalization of marijuana in Denver, Colorado: A joint study between two Denver hospitals

INTRODUCTION

The effect of marijuana on human health has been studied extensively. Marijuana intoxication has been shown to affect performance, attention span, and reaction time. The public health relationship between trauma and cannabis use has also been studied, with mixed conclusions. In this report, the effect of marijuana legalization on many aspects of facial trauma at two hospitals in Denver, Colorado is examined.

METHODS

A retrospective review of the electronic medical records was undertaken. Mann-Whitney U tests were used to compare age of patients before and after legalization, and chi squared analyses were used to compare mechanism of injury, and fracture types before and after recreational marijuana legalization in Denver, Colorado. Geographical location of patients was also considered.

RESULTS

No significant increase was found in race before and after marijuana legalization (p=0.19). A significant increase in age was found before (M=39.54,SD=16.37), and after (M=41.38,SD=16.66) legalization (p<0.01). Maxillary and skull base fracture proportions significantly increased following legalization (p<0.001 and p<0.001respectively). No significant differences were seen in the proportion of patients who lived in urban and rural counties before and after legalization (p>0.05).

CONCLUSION

Public health efforts should be directed towards educating residents and visitors of Colorado on the effects and toxicology of marijuana. More epidemiologic studies are needed for further assessment of the long-term effects of the legalization of marijuana on the population.

Driving under the influence of drugs: Perceptions and attitudes of New Zealand drivers

This study explored the patterns of drug driving in New Zealand by investigating 1) drivers' perceptions about impairment caused by legal and illegal drugs 2) countermeasures employed by drivers when under the influence of drugs (e.g., decisions not to drive) 3) drivers' attitudes about police enforcement of drug driving and 4) the factors that predict the likelihood of engaging in drug driving. Participants (n=434) were licensed drivers who completed an online questionnaire. Results of the questionnaire indicated that drivers rated hallucinogens and opiates as being the illegal drugs producing the highest level of driving impairment and cannabis the lowest. For legal drugs, sedatives were rated as having the highest driving impairment and anti-nausea and anti-depressants the lowest. Respondents' drug use history had an effect on their ratings of impairment for anti-anxiety drugs, anti-depressants, kava, sedatives, cannabis and hallucinogens such that drug users reported higher impairment ratings than Non-user. Making a decision not to drive after taking drugs was reported by users of alcohol (73.6%), cannabis (57.0%), strong painkillers (42.5%), and anti-depressants (10.0%). Respondents who reported drink driving were 3.26 times more likely to report drug driving than those reporting no drink driving. Respondents also showed greater acceptance towards driving under the influence of legal drugs (43.5%) compared to illegal drugs (10.3%). Those who did not have favourable attitudes about drug driving were less likely to report having driven under the influence of drugs. Drivers in this sample were less aware of the potential negative effects of legal drugs on driving compared to illegal drugs. More than half the respondents from this study acknowledged drug driving as a road safety issue which needs more resources dedicated to it.

The role of drug and alcohol use and the risk of motor vehicle crashes in Shiraz, Iran, 2014: A case-crossover study

BACKGROUND

Traffic accidents and traffic-related injuries and mortality have become a major public health concern in Iran. This study aimed to examine the role of drug and alcohol use in motor vehicle accidents in Iran.

METHODS

This case-crossover study was conducted on 441 drivers who survived a road traffic crash and were taken to the emergency department of Shahid Rajaee trauma hospital in Shiraz, southern Iran. Data were collected using checklists that included demographic characteristics and drug and alcohol use prior to driving. Alcohol and drug use was identified through self-report, and cannabis, morphine, and methamphetamine urine tests were used to confirm drug abuse among drivers.

RESULTS

In total 17.9% of drivers reported using drugs (cannabis, opium, or metamphetamine) and 8.84% of drivers reported consuming alcohol prior to the collision. The crude odds ratios (ORs) for having a crash for opium, cannabis, and metamphetamine were 1.94 (95% interval confidence [CI], 1.11-3.38), 2.37 (95% CI, 1.03-5.42), 5.5 (95% CI, 1.21-24.81), respectively, and for all drugs was 3.83 (95% CI, 2.28-6.43). The OR for alcohol was 3.5 (95% CI, 1.73-7.06) based on self-report.

CONCLUSION

Drug and alcohol use are increasing the risk of traffic crashes in Iran. Risk-reducing programs must be designed and implemented.

Lower-Risk Cannabis Use Guidelines: A Comprehensive Update of Evidence and Recommendations

BACKGROUND

Cannabis use is common in North America, especially among young people, and is associated with a risk of various acute and chronic adverse health outcomes. Cannabis control regimes are evolving, for example toward a national legalization policy in Canada, with the aim to improve public health, and thus require evidence-based interventions. As cannabis-related health outcomes may be influenced by behaviors that are modifiable by the user, evidence-based Lower-Risk Cannabis Use Guidelines (LRCUG)-akin to similar guidelines in other health fields-offer a valuable, targeted prevention tool to improve public health outcomes.

OBJECTIVES

To systematically review, update, and quality-grade evidence on behavioral factors determining adverse health outcomes from cannabis that may be modifiable by the user, and translate this evidence into revised LRCUG as a public health intervention tool based on an expert consensus process.

SEARCH METHODS

We used pertinent medical search terms and structured search strategies, to search MEDLINE, EMBASE, PsycINFO, Cochrane Library databases, and reference lists primarily for systematic reviews and meta-analyses, and additional evidence on modifiable risk factors for adverse health outcomes from cannabis use.

SELECTION CRITERIA

We included studies if they focused on potentially modifiable behavior-based factors for risks or harms for health from cannabis use, and excluded studies if cannabis use was assessed for therapeutic purposes.

DATA COLLECTION AND ANALYSIS

We screened the titles and abstracts of all studies identified by the search strategy and assessed the full texts of all potentially eligible studies for inclusion; 2 of the authors independently extracted the data of all studies included in this review. We created Preferred Reporting Items for Systematic Reviews and Meta-Analyses flow-charts for each of the topical searches. Subsequently, we summarized the evidence by behavioral factor topic, quality-graded it by following standard (Grading of Recommendations Assessment, Development, and Evaluation; GRADE) criteria, and translated it into the LRCUG recommendations by the author expert collective on the basis of an iterative consensus process.

MAIN RESULTS

For most recommendations, there was at least "substantial" (i.e., good-quality) evidence. We developed 10 major recommendations for lower-risk use: (1) the most effective way to avoid cannabis use-related health risks is abstinence, (2) avoid early age initiation of cannabis use (i.e., definitively before the age of 16 years), (3) choose low-potency tetrahydrocannabinol (THC) or balanced THC-to-cannabidiol (CBD)-ratio cannabis products, (4) abstain from using synthetic cannabinoids, (5) avoid combusted cannabis inhalation and give preference to nonsmoking use methods, (6) avoid deep or other risky inhalation practices, (7) avoid high-frequency (e.g., daily or near-daily) cannabis use, (8) abstain from cannabis-impaired driving, (9) populations at higher risk for cannabis use-related health problems should avoid use altogether, and (10) avoid combining previously mentioned risk behaviors (e.g., early initiation and high-frequency use).

AUTHORS' CONCLUSIONS

Evidence indicates that a substantial extent of the risk of adverse health outcomes from cannabis use may be reduced by informed behavioral choices among users. The evidence-based LRCUG serve as a population-level education and intervention tool to inform such user choices toward improved public health outcomes. However, the LRCUG ought to be systematically communicated and supported by key regulation measures (e.g., cannabis product labeling, content regulation) to be effective. All of these measures are concretely possible under emerging legalization regimes, and should be actively implemented by regulatory authorities. The population-level impact of the LRCUG toward reducing cannabis use-related health risks should be evaluated. Public health implications. Cannabis control regimes are evolving, including legalization in North America, with uncertain impacts on public health. Evidence-based LRCUG offer a potentially valuable population-level tool to reduce the risk of adverse health outcomes from cannabis use among (especially young) users in legalization contexts, and hence to contribute to improved public health outcomes.

Self-reported driving under the influence of alcohol and cannabis among Ontario students: Associations with graduated licensing, risk taking, and substance abuse

OBJECTIVE

This article describes the patterns of self-reported driving under the influence of alcohol (DUIA) and driving under the influence of cannabis (DUIC) among licensed Ontario students in 2009 and examines their associations with graduated licensing, risk taking, and substance use problems for understanding DUIA and DUIC behaviors. Ontario's graduated licensing system requires new drivers to hold a G1 license for a minimum of 8 months and a G2 license for a minimum of 12 months before a full and unrestricted G license can be obtained. Among other restrictions, G1 drivers must maintain a 0 blood alcohol content (BAC), have an experienced driver in the passenger seat, not drive on any high-speed expressways, and not drive between the hours of midnight and 5 a.m. A G2 license is more similar to a G license, with fewer restrictions.

METHOD

This study analyzed data from the 2009 Ontario Student Drug Use and Health Survey (OSDUHS). The OSDUHS is a biennial population-based survey of students (grades 7 to 12) in Ontario, Canada.

RESULTS

The results showed that 16.3% of licensed students in Ontario reported DUIC and 11.5% reported DUIA during the past year. After controlling for the effect of age, type of license emerged as a robust predictor for both DUIA and DUIC behavior, because students with a G2 and full license were significantly more likely to report DUIA and DUIC than drivers with a G1 license. Multivariate analyses suggested that risk-seeking behaviors were more important for understanding DUIA behavior than for DUIC behavior. Elevated problem indicators for alcohol and for cannabis were associated with DUIA and DUIC, respectively.

CONCLUSIONS

Though much attention has been paid to drinking and driving among adolescents, this research shows that more Ontario students now report driving after cannabis use than after drinking alcohol. The results identify important correlates of both behaviors that may be useful for prevention purposes.

Patterns of marijuana and tobacco use associated with suboptimal self-rated health among US adult ever users of marijuana

The purpose of this study was to examine the patterns of marijuana and tobacco use and their associations with suboptimal self-rated health (SRH) among US adults who reported "ever, even once, using marijuana or hashish." Data came from the 2009-2012 National Health and Nutrition Examination Survey, restricting to respondents aged 20 years and older who reported using marijuana at least once in their lifetime (n = 3,210). We assessed the age-adjusted prevalence of mutually exclusive groups of regular (at least once a month for more than one year) and non-regular marijuana smoking by current (serum cotinine ≥ 3.08 ng/mL) and not current use of tobacco. Suboptimal SRH status was defined as "fair" or "poor" in response to the question "Would you say that in general your health is excellent, very good, good, fair, or poor?" We produced prevalence ratios with multivariable log-linear regression models. Among ever users of marijuana, the age-adjusted prevalence of regular marijuana smoking with current tobacco use, non-regular marijuana smoking with current tobacco use, and regular marijuana smoking without current tobacco use was 24.7%, 15.2%, and 21.1%, respectively. When compared to non-regular marijuana smokers without current tobacco use, the adjusted prevalence ratio for reporting suboptimal SRH was 1.98 (95% CI: 1.50-2.61), 1.82 (95% CI: 1.40-2.37), and 1.34 (95% CI: 1.05-1.69), respectively. In conclusion, among adult ever users of marijuana, current tobacco use is high and strongly associated with suboptimal SRH; regular marijuana smoking with or without current tobacco use is significantly associated with suboptimal SRH.

Cannabinoid disposition in oral fluid after controlled smoked, vaporized, and oral cannabis administration

Oral fluid (OF) is an important matrix for monitoring drugs. Smoking cannabis is common, but vaporization and edible consumption also are popular. OF pharmacokinetics are available for controlled smoked cannabis, but few data exist for vaporized and oral routes. Frequent and occasional cannabis smokers were recruited as participants for four dosing sessions including one active (6.9% Δ9 -tetrahydrocannabinol, THC) or placebo cannabis-containing brownie, followed by one active or placebo cigarette, or one active or placebo vaporized cannabis dose. Only one active dose was administered per session. OF was collected before and up to 54 (occasional) or 72 (frequent) h after dosing from cannabis smokers. THC, 11-hydroxy-THC (11-OH-THC), 11-nor-9-carboxy-THC (THCCOOH), tetrahydrocannabivarin (THCV), cannabidiol (CBD), and cannabigerol (CBG) were quantified by liquid chromatography-tandem mass spectrometry. OF cannabinoid Cmax occurred during or immediately after cannabis consumption due to oral mucosa contamination. Significantly greater THC Cmax and significantly later THCV, CBD, and CBG tlast were observed after smoked and vaporized cannabis compared to oral cannabis in frequent smokers only. No significant differences in THC, 11-OH-THC, THCV, CBD, or CBG tmax between routes were observed for either group. For occasional smokers, more 11-OH-THC and THCCOOH-positive specimens were observed after oral dosing than after inhaled routes, increasing % positive cannabinoid results and widening metabolite detection windows after oral cannabis consumption. Utilizing 0.3 µg/L THCV and CBG cut-offs resulted in detection windows indicative of recent cannabis intake. OF pharmacokinetics after high potency CBD cannabis are not yet available precluding its use currently as a marker of recent use. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

Estimating the harms and costs of cannabis-attributable collisions in the Canadian provinces

INTRODUCTION

In 2012, 10% of Canadians used cannabis and just under half of those who use cannabis were estimated to have driven under the influence of cannabis. Substantial evidence has accumulated to indicate that driving after cannabis use increases collision risk significantly; however, little is known about the extent and costs associated with cannabis-related traffic collisions. This study quantifies the costs of cannabis-related traffic collisions in the Canadian provinces.

METHODS

Province and age specific cannabis-attributable fractions (CAFs) were calculated for traffic collisions of varying severity. The CAFs were applied to traffic collision data in order to estimate the total number of persons involved in cannabis-attributable fatal, injury and property damage only collisions. Social cost values, based on willingness-to-pay and direct costs, were applied to estimate the costs associated with cannabis-related traffic collisions. The 95% confidence intervals were calculated using Monte Carlo methodology.

RESULTS

Cannabis-attributable traffic collisions were estimated to have caused 75 deaths (95% CI: 0-213), 4407 injuries (95% CI: 20-11,549) and 7794 people (95% CI: 3107-13,086) were involved in property damage only collisions in Canada in 2012, totalling $1,094,972,062 (95% CI: 37,069,392-2,934,108,175) with costs being highest among younger people.

DISCUSSION

The cannabis-attributable driving harms and costs are substantial. The harm and cost of cannabis-related collisions is an important factor to consider as Canada looks to legalize and regulate the sale of cannabis. This analysis provides evidence to help inform Canadian policy to reduce the human and economic costs of drug-impaired driving.

Frequent marijuana use and driving risk behaviours in Canadian youth

Background

A better understanding of the relations between patterns of marijuana use and driving risks in young adulthood is needed.

Methods

Secondary analyses of self-report data from the Victoria Healthy Youth Survey. Youth (baseline ages 12 to 18; N=662; 52% females) were interviewed biannually (on six occasions) from 2003 to 2013 and classified as abstainers (i.e., used no marijuana in past 12 months), occasional users (i.e., used at most once per week), and frequent users (i.e., used more than once a week).

Results

In the frequent user group, 80% of males and 75% of females reported 'being in a car driven by driver (including themselves) using marijuana or other drugs in the last 30 days', 64% of males and 33% of females reported that they were 'intoxicated' with marijuana while operating a vehicle and 50% of males and 42% of females reported being in a car driven by a driver using alcohol. In addition, 28% of occasional users and also a small proportion of abstainers reported 'being in a car driven by a driver using marijuana or other drugs in the last 30 days'.

Interpretation

The high frequency of driving risk behaviours, particularly for frequent users, suggest that plans for legalization of recreational use should anticipate the costs of preventive education efforts that present an accurate picture of potential risks for driving. Youth also need to understand risks for dependence, and screening for and treatment of marijuana use disorders is needed.

Cannabis Edibles: Blood and Oral Fluid Cannabinoid Pharmacokinetics and Evaluation of Oral Fluid Screening Devices for Predicting Δ9-Tetrahydrocannabinol in Blood and Oral Fluid following Cannabis Brownie Administration

BACKGROUND

Roadside oral fluid (OF) Δ9-tetrahydrocannabinol (THC) detection indicates recent cannabis intake. OF and blood THC pharmacokinetic data are limited and there are no on-site OF screening performance evaluations after controlled edible cannabis.

CONTENT

We reviewed OF and blood cannabinoid pharmacokinetics and performance evaluations of the Draeger DrugTest®5000 (DT5000) and Alere™ DDS®2 (DDS2) on-site OF screening devices. We also present data from a controlled oral cannabis administration session.

SUMMARY

OF THC maximum concentrations (Cmax) were similar in frequent as compared to occasional smokers, while blood THC Cmax were higher in frequent [mean (range) 17.7 (8.0–36.1) μg/L] smokers compared to occasional [8.2 (3.2–14.3) μg/L] smokers. Minor cannabinoids Δ9-tetrahydrocannabivarin and cannabigerol were never detected in blood, and not in OF by 5 or 8 h, respectively, with 0.3 μg/L cutoffs. Recommended performance (analytical sensitivity, specificity, and efficiency) criteria for screening devices of ≥80% are difficult to meet when maximizing true positive (TP) results with confirmation cutoffs below the screening cutoff. TPs were greatest with OF confirmation cutoffs of THC ≥1 and ≥2 μg/L, but analytical sensitivities were &lt;80% due to false negative tests arising from confirmation cutoffs below the DT5000 and DDS2 screening cutoffs; all criteria were &gt;80% with an OF THC ≥5 μg/L cutoff. Performance criteria also were &gt;80% with a blood THC ≥5 μg/L confirmation cutoff; however, positive OF screening results might not confirm due to the time required to collect blood after a crash or police stop. OF confirmation is recommended for roadside OF screening.

ClinicalTrials.gov identification number: NCT02177513

"Is Marijuana Even a Drug?" A Qualitative Study of How Teens View Marijuana Use and Why They Use It

This qualitative study examines how youth in the San Francisco Bay Area perceive marijuana and their motives for using or not using marijuana. Current regular users were more likely to perceive marijuana smoking as an enjoyable activity, comparable to a hobby or sport. Current occasional users commonly reported smoking marijuana when it was offered to them, on special occasions, and sometimes as a result of not wanting to be left out. Most former regular users reported quitting marijuana use due to getting into trouble, being ordered into drug treatment and/or being drug tested. Former occasional users mostly reported that they did not like the somatic effects of marijuana and did not feel it enhanced their social interactions or activities. Teens who reported never having used marijuana did so out of concerns for their health. Except for never-users, marijuana was seen as safe to use. Teens mentioned the widespread use of marijuana by people they know and legalization for medical and recreational use as evidence that marijuana is not harmful. The findings suggest that normalization of marijuana use is taking place. Differences in motives for and against marijuana use should be taken into consideration when designing interventions and prevention messages.