Drug use and fatal motor vehicle crashes: a case-control study

Identifying standardised neuropsychological test measures sensitive to cannabis consumption: A systematic review

BACKGROUND

While numerous studies have indicated acute neurocognitive changes following the administration of Δ9-tetrahydrocannabinol (THC; the psychoactive component of cannabis), the standardised neuropsychological tests most sensitive to THC are yet to be identified. As such, this systematic review analysed scientific evidence (since 2000) on the effects of THC on standardised neuropsychological test measures.

METHODS

This review was conducted in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies were eligible for inclusion if they utilised a between or within-subjects design in testing for differences in standardised neuropsychological test performance following the consumption of THC.

RESULTS/DISCUSSION

Sufficient data were identified to examine 8 standardised neuropsychological test measures, with 12 studies being eligible for inclusion in the review. It was identified that the Cambridge Neuropsychological Test Automated Battery (CANTAB) subtest Spatial Working Memory, Hopkins Verbal Learning Test, Prose Recall and Rey Auditory Verbal Learning Test were sensitive to cannabis consumption.

LIMITATIONS

However, due to substantial variability observed across studies, the data could not be quantitatively analysed. It was noted that few studies employed standardised neuropsychological measures in assessing the effects of THC.

CONCLUSION

Overall, the findings highlight the need for further research examining the effects of cannabis on standardised and validated measures of neurocognitive function. Such an approach can be considered an important first step towards developing behavioural measures of impairment.

Non-Obstetric Maternal Mortality Trends by Race in the United States

OBJECTIVES

Public health interventions to reduce maternal mortality have largely focused on obstetric causes of death. However, previous studies have noted that non-obstetrics factors, such as motor vehicle accidents, substance overdoses, homicides, and suicides, may account for a large proportion of maternal deaths. The study objective was to examine trends in maternal deaths from non-obstetric causes across races in the United States (US).

METHODS

A population-based cross-sectional study was conducted on 80,710,348 live births using data from the "Birth Data" and "Mortality Multiple Cause" files compiled by the Centers for Disease Control and Prevention from 2000 to 2019. The annual incidence of maternal deaths attributed to non-obstetric causes (/100,000 live-births) during pregnancy and up to 42 days postpartum were calculated across racial groups. Then the effects of race on the risk of non-obstetric maternal mortality and temporal changes over the study period were examined using logistic regression models.

RESULTS

From 2000 to 2019, a total 7,334 women died during pregnancy, childbirth, and within 42 days postpartum from non-obstetric causes, representing 34.5% (7,334/21,241) of all maternal mortality. Of non-obstetric deaths, 31.3% were caused by transport accidents and 27.3% by accidental poisoning. American Indian women were found to have the highest risk of non-obstetric maternal mortality (OR 2.20,95% CI 1.90-2.56), and 46.1% (176/382) of all deaths among pregnant American Indian women were caused by non-obstetric complications. Risk of non-obstetric maternal mortality increased overall during the 20-year study period, with a greater increase among Black (1.15, 1.13-1.17) and American Indian women (1.17, 1.13-1.21).

CONCLUSION

Non-obstetric causes of death have become increasingly prevalent in the US, especially in American Indian women. Novel interventions to address these non-obstetric factors should especially target American Indian women to improve maternal outcomes.

Lateral spatial biases in naturalistic and simulated driving: Does pseudoneglect influence performance?

Whereas a rightward bump is more likely than a leftward bump when walking through a doorway, investigations into potential similar asymmetries for drivers are limited. The research presented here aims to determine the influence of innate lateral spatial biases when driving. Data from the Strategic Highway Research Program Naturalistic Driving Study (SHRP 2 NDS) and a driving simulation were used to address our research questions. Data points from SHRP 2 were aggregated within relevant variables (e.g., left/right obstacles). In the simulation, participants drove in ways that were consistent with their everyday driving in urban and rural environments. Collision frequency, collision severity and average lateral lane position were analyzed with rightward biases throughout both analyzes. SHRP 2 data indicated greater likelihoods of collisions when vehicles crossed the right line/edge of the road and when making a right turn. There were more collisions with obstacles on the right side, which were also more severe, and greater rightward lane deviations in the driving simulation, contrasted with more severe collisions on the left side in SHRP 2 data, possibly because of the presence of traffic. These findings suggest that previously observed rightward biases in distant space when walking are also present when driving.

Time- and temperature-dependent postmortem ∆9-tetrahydrocannabinol concentration changes in rabbits following controlled inhaled cannabis administration

ostmortem redistribution (PMR), a well-known phenomenon in forensic toxicology, can result in substantial changes in drug concentrations after death, depending on the chemical characteristics of the drug, blood collection site, storage conditions of the body and postmortem interval (PMI). Limited PMR data are available for ∆9-tetrahydrocannabinol (THC), the primary psychoactive component in Cannabis sativa. PMR was evaluated after controlled cannabis inhalation via a smoking machine and exposure chamber in New Zealand white rabbits. Necropsies were performed on five control rabbits immediately after euthanasia, whereas 27 others were stored at room temperature (21°C) or refrigerated conditions (4°C) until necropsy at 2, 6, 16, 24 or 36 h after death. THC and its Phase I and glucuronidated Phase II metabolites were quantified in blood, vitreous humor, urine, bile and tissues by liquid chromatography-tandem mass spectrometry (LC-MS-MS). Under refrigerated temperature, heart blood THC concentrations significantly increased at PMI 2 h in rabbits, whereas peripheral blood THC concentrations showed a significant increase at PMI 16 h. Central:peripheral blood and liver:peripheral blood ratios for THC ranged from 0.13 to 4.1 and 0.28 to 8.9, respectively. Lung revealed the highest THC concentrations, while brain and liver exhibited the most stable THC concentrations over time. This report contributes much needed data to our understanding of postmortem THC behavior and can aid toxicologists in the interpretation of THC concentrations in medicolegal death investigations.

Cannabis-Impaired driving: ethical considerations for the primary care practitioner

Background: Widespread cannabis consumption and recreational cannabis legalization is thought to have led to an increase in motor vehicle accidents, although there currently lacks ethical guidance for primary care practitioners on cannabis-impaired driving.Objective: The aim was to develop an ethical framework for primary care providers on cannabis-impaired driving.Methods: An ethical analysis in the form of a critical interpretive review was undertaken, using a systematic approach to determine the appropriate action to a given situation with evidence to substantiate its claims. The search strategy was designed to answer the research question: What are some ethical concerns for primary care providers to consider when cannabis-impaired driving is suspected? Four databases were searched in December 2021 using keywords related to cannabis, impaired driving, ethics, and primary care. The resulting evidence was synthesized as recommendations for primary care practice.Results: The ethical approach for primary care practitioners in addressing cannabis-impaired driving can be summarized as the duty to always inform, provide care through prevention and harm reduction strategies, and report when necessary. The prevention of cannabis-impaired driving should not fall on the sole responsibility of primary care practitioners. As this review offers a high-level discussion of the ethical considerations in cannabis-impaired driving, specific recommendations will depend upon the legal and policy designations of individual jurisdictions.Conclusion: Ultimately, the practitioner should manage cannabis-impaired driving in a way that fosters the therapeutic relationship in patient-centered care, through motivational discussions, collaboration with specialists, skills for self-management, patient empowerment, and support. KEY MESSAGES  Take-Home Points for Primary Care Practitioners in Cannabis-Impaired Driving  •  For patients who report driving frequently and using cannabis, the frequency of use, dosage, form of cannabis, tolerance levels, and withdrawal symptoms should be discussed, while informing the patient of the risks, harms, and legal consequences associated with cannabis-impaired driving.  •  The practitioner's primary responsibility in the cannabis-impaired driving context is to provide care to patients who drive and consume cannabis, which may include referring patients to mental health care to manage addictive or problematic behaviors associated with cannabis use.  •  Practitioners may have a duty to report cannabis-impaired driving to legal authorities (such as law enforcement) when the user engages in harmful behavior to themselves or others.

Social Media and Selfie-Related Mortality Amid COVID-19: Interrupted Time Series Analysis

BACKGROUND

COVID-19 had a considerable impact on mortality, but its effect on behaviors associated with social media remains unclear. As travel decreased due to lockdowns during the pandemic, selfie-related mortality may have decreased, as fewer individuals were taking smartphone photographs in risky locations.

OBJECTIVE

In this study, we examined the effect of the COVID-19 pandemic on trends in selfie-related mortality.

METHODS

We identified fatal selfie-related injuries reported in web-based news reports worldwide between March 2014 and April 2021, including the deaths of individuals attempting a selfie photograph or anyone else present during the incident. The main outcome measure was the total number of selfie-related deaths per month. We used interrupted time series regression to estimate the monthly change in the number of selfie-related deaths over time, comparing the period before the pandemic (March 2014 to February 2020) with the period during the pandemic (March 2020 to April 2021).

RESULTS

The study included a total of 332 selfie-related deaths occurring between March 2014 and April 2021, with 18 (5.4%) deaths during the pandemic. Most selfie-related deaths occurred in India (n=153, 46.1%) and involved men (n=221, 66.6%) and young individuals (n=296, 89.2%). During the pandemic, two-thirds of selfie-related deaths were due to falls, whereas a greater proportion of selfie-related deaths before the pandemic were due to drowning. Based on interrupted time series regression, there was an average of 1.3 selfie-related deaths per month during the pandemic, compared with 4.3 deaths per month before the pandemic. The number of selfie-related deaths decreased by 2.6 in the first month of the pandemic alone and continued to decrease thereafter.

CONCLUSIONS

Our findings indicate that the COVID-19 pandemic led to a marked decrease in selfie-related mortality, suggesting that lockdowns and travel restrictions likely prevented hazardous selfie-taking. The decrease in selfie-related mortality occurred despite a potential increase in social media use during the pandemic.

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.

Collisions and cannabis: Measuring the effect of recreational marijuana legalization on traffic crashes in Washington State

OBJECTIVE

Washington State was among the first states in the US to legalize recreational consumption and retail sales of marijuana. Recreational use of cannabis was legalized December 6, 2012, following the passage of Initiative 502 30 days prior. Roughly 19 months later the first retail cannabis stores opened their doors for public sales ("commercialization"). I measure the impact of cannabis legalization and commercialization on traffic collisions in Washington State.

METHODS

With county-level vehicle crash data from the Washington State Department of Transportation collected monthly, I utilize an interrupted time-series framework with Poisson estimation to compare traffic collisions with recreational retail cannabis sales revenue from 2011 (three years pre-commercialization) through 2017 (three years post-commercialization). First, I measure the shift in collisions brought about by Washington's 2012 cannabis legalization. Then, I compare retail cannabis sales-a measure of commercialization-to traffic collisions based on severity of injury (fatal, severe injury, minor injury, non-injury, and all).

RESULTS

After controlling for confounding factors, evidence suggests that recreational cannabis legalization led to fewer fatal and serious injury collisions. Retail cannabis sales generally correlate with more traffic collisions, particularly for less severe (minor injury) crashes. These findings are robust to the inclusion of additional control variables pertaining to county-level cannabis usage and driving behavior while intoxicated.

CONCLUSIONS

Cannabis legalization led to fewer fatal, serious, and minor injury collisions. Commercialization (cannabis sales) correlated with an increase in less severe crashes. Although cannabis use generally increased in Washington State following legalization/commercialization, survey data suggest that driving behavior while under the influence of cannabis did not change significantly over the post-commercialization period. Future research should focus on measuring the dose-dependent impact of cannabis consumption on traffic collisions. This should include recognition of the importance of cannabis dosing, timing, and route of consumption. Lastly, the dangers of poly-drug driving-particularly cannabis and alcohol-are well established and should be high priority for further research.

Association of medical conditions and firearm suicide among legal handgun purchasers in California: a case-control study

BACKGROUND

Suicide is a pressing public health problem, and firearm owners are at especially elevated risk. Certain health conditions are markers of suicide risk, but more research is needed on clinical risk markers for suicide among firearm owners specifically. Our goal was to examine associations of emergency department and inpatient hospital visits for behavioral and physical health conditions with firearm suicide among handgun purchasers.

METHODS

This was a case-control study of 5415 legal handgun purchasers in California who died between January 1, 2008, and December 31, 2013. Cases were firearm suicide decedents; controls were motor vehicle crash decedents. Exposures were emergency department and hospital visits for six categories of health diagnoses in the 3 years prior to death. To account for selection bias due to deceased controls, we used probabilistic quantitative bias analysis to generate bias-adjusted estimates.

RESULTS

There were 3862 firearm suicide decedents and 1553 motor vehicle crash decedents. In multivariable models, suicidal ideation/attempt (OR 4.92; 95% CI 3.27-7.40), mental illness (OR 1.97; 95% CI 1.60-2.43), drug use disorder (OR 1.40; 95% CI 1.05-1.88), pain (OR 1.34; 95% CI 1.07-1.69), and alcohol use disorder (OR 1.29; 95% CI 1.01-1.65) were associated with higher odds of firearm suicide. When adjusting for all conditions simultaneously, only the associations for suicidal ideation/attempt and mental illness remained significant. Quantitative bias analysis indicated that observed associations were generally biased downward. For example, the bias-adjusted OR for suicidal ideation/attempt was 8.39 (95% simulation interval 5.46-13.04), almost twice that of the observed OR.

CONCLUSIONS

Diagnoses for behavioral health conditions were markers for firearm suicide risk among handgun purchasers, even for conservative estimates that did not adjust for selection bias. Encounters with the healthcare system may provide opportunities to identify firearm owners at high risk of suicide.

The impact of recreational cannabis markets on motor vehicle accident, suicide, and opioid overdose fatalities

In the U.S., an increasing number of states are legalizing regulated commercial markets for recreational cannabis, which allows private industry to produce, distribute, and sell marijuana to those 21 and older. The health impacts of these markets are not fully understood. Preliminary evidence suggests recreational markets may be associated with increased use among adults, which indicates there may be downstream health impacts on outcomes related to cannabis use. Three causes of death that are linked to cannabis use are motor vehicle accidents, suicide, and opioid overdose. Drawing on data from U.S. death certificates from 2009 to 2019, we conducted a difference-in-differences analysis to estimate the impact of recreational markets on fatalities from motor vehicle accidents, suicide, and opioid overdose in seven states: Colorado, Washington, Oregon, Alaska, Nevada, California, and Massachusetts. States with comprehensive medical cannabis programs with similar pre-trends in deaths were used as comparisons. For each outcome, a pooled estimate was generated with a meta-analysis using random effects models. The results revealed substantial increases in crash fatalities in Colorado, Oregon, Alaska, and California of 16%, 22%, 20%, and 14%, respectively. Based on estimates from all seven states, recreational markets were associated with a 10% increase in motor vehicle accident deaths, on average. This study found no evidence that recreational markets impacted suicides. Most states saw a relative reduction in opioid overdose death that ranged between 3 and 28%. On average, recreational markets were associated with an 11% reduction in opioid overdose fatalities.

Reporting of unknown drug test results in the Fatality Analysis Reporting System and associated factors, 2000-2020

OBJECTIVE

To investigate how the percentage of unknown drug test results among drug-tested drivers in the Fatality Analysis Reporting System (FARS) has trended over the past 2 decades and to evaluate factors that may affect a drug-tested driver having unknown test results in FARS.

METHODS

The percentage of unknown test results among fatally injured drivers who were tested for drugs in FARS was assessed from 2000 to 2020. Trends in annual FARS drug testing data were compared with those for alcohol testing. In addition, the percentage of unknown drug test results was regressed on several factors that have been shown to be associated with higher risk of drug-involved crash fatalities.

RESULTS

The percentage of unknown drug test results in FARS has decreased drastically over the past 2 decades, and the percentage of unknown drug test data gradually matched that of alcohol data over the study period. Multiple factors such as the fatally injured drivers' age and whether the crash occurred in an urban/rural area were found to be statistically significantly associated with the percentage of unknown drug test results in FARS.

CONCLUSIONS

The percentage of unknown test results in FARS drug data is decreasing, and the significant associated factors found in this study may help identify additional strategies for reducing unknown drug test results. Future research should focus on continued improvement of FARS data, given the importance of FARS in understanding fatal crashes and informing strategies for prevention of crash-related injuries and fatalities in the United States.

Ironic effects of political ideology and increased risk-taking in Ohio drivers during COVID-19 shutdown

In March 2020, Ohio, along with many other states, enacted a stay-at-home order (i.e., "shutdown") to limit the spread of COVID-19. As a result of lower traffic, crashes should also have declined. We investigated whether crash rates declined in Ohio during the stay-at-home order and explore possible predictors for the decrease, such as reduced travel in compliance with the order, along with speeding, alcohol, and drug use. In addition, we examined whether support for President Trump would relate to greater travel and greater crashes (particularly during the stay-at-home order, when greater travel indicated lower compliance). The overall rate of crashes fell as people stayed home, mainly due to a decline in minor crashes. In contrast, the rate of serious crashes did not fall. Instead, percentage of alcohol-related crashes increased during the stay-at-home order, and the reduction in travel was associated with greater speeding-related crashes. Because alcohol and speeding tend to increase crash severity, these two factors may explain why severe crash rates were not reduced by lower traffic. Instead, it appears that those drivers remaining on the roads during the shutdown may have been more prone to risky behaviors, evidenced by a greater percentage of alcohol-related crashes across the state during the shutdown and greater speed-related crashes in counties with less traffic. In addition, county-level support for President Trump indirectly predicted greater rates of crashes (of all types) via increased travel (i.e., lower compliance with the shutdown), even while controlling for county-level income, rurality, and Appalachian region. Importantly, this mediated effect was stronger during the weeks of the shutdown, when greater travel indicated lower compliance. Thus, lower compliance with the stay-at-home order and increased risky driving behaviors by remaining drivers may explain why lower traffic did not lead to lower serious crashes.

Registry Data in Injury Research: Study Designs and Interpretation

Purpose of Review

Injury data is frequently captured in registries that form a census of 100% of known cases that meet specified inclusion criteria. These data are routinely used in injury research with a variety of study designs. We reviewed study designs commonly used with data extracted from injury registries and evaluated the advantages and disadvantages of each design type.

Recent Findings

Registry data are suited to 5 major design types: (1) Description, (2) Ecologic (with Ecologic Cohort as a particularly informative sub-type), (3) Case-control (with location-based and culpability studies as salient subtypes), (4) Case-only (including case-case and case-crossover subtypes), and (5) Outcomes.

Summary

Registries are an important resource for injury research. Investigators considering use of a registry should be aware of the advantages and disadvantages of available study designs.

Effects of psychotropic drugs on ocular parameters relevant to traffic safety: A systematic review

Driving is a complex neurobehavioural task necessitating the rapid selection, uptake, and processing of visual information. Eye movements that are critical for the execution of visually guided behaviour such as driving are also sensitive to the effects of psychotropic substances. The Embase (via Ovid), EBSCOHost, Psynet, Pubmed, Scopus and Web of Science databases were examined from January 01st, 2000 to December 31st, 2021. Study selection, data extraction and Cochrane Risk of Bias (RoB2) assessments were conducted according to PRISMA guidelines. The review was prospectively registered (CRD42021267554). In total, 36 full-text articles examined the effects of six principal psychotropic drug classes on measures of oculomotor parameters relevant to driving. Centrally depressing substances affect oculomotor responses in a dose-dependent manner. Psychostimulants improve maximal speed, but not accuracy, of visual search behaviours. Inhaled Δ-9-tetrahydrocannabinol (THC) increases inattention (saccadic inaccuracy) but does not consistently affect other oculomotor parameters. Alterations to composite ocular parameters due to psychoactive substance usage likely differently compromises performance precision during driving through impaired ability to select and process dynamic visual information.

Prevalence and correlates of driving under the influence of stimulants: Evidence from a national sample

BACKGROUND

Several million Americans use illicit stimulants every month and national data suggest stimulant use is increasing. However, little evidence exists that examines the prevalence and correlates of driving under the influence of stimulants (DUIS). The present study aimed to provide new evidence on the prevalence of DUIS in the U.S. adult population.

METHODS

This study examined data from 170,944 adults 18 and older in the 2016-2019 National Survey on Drug Use and Health. Using Stata and R, we estimated the prevalence and key correlates of DUIS among adults in the United States.

RESULTS

The overall prevalence of DUIS was 0.7% among adults in general and 28.3% among past-year stimulant users. Among the full adult sample, the prevalence of DUI cocaine was 0.5% and the prevalence of DUI methamphetamine was 0.3%. More than one in five (21.6%) adults with past year cocaine use reported DUI of cocaine, while nearly one half (47.2%) of adults with past year methamphetamine use reported DUI of methamphetamine. There is also a substantially higher likelihood of driving under the influence of stimulants among individuals reporting early onset of use and among those meeting criteria for cocaine/methamphetamine use disorders. Among adults who used cocaine/methamphetamine, those who reported driving under the influence of stimulants were more than 2 times more likely to experience a depressive episode or psychological distress.

CONCLUSION

Findings suggest that prevention/treatment approaches focused on multiple substances as well as mental health needs may be most appropriate for addressing the challenge of DUIS.

Cannabis legalization and driving under the influence of cannabis in a national U.S. Sample

•

A national survey sampled current cannabis users.

•

Users in medical cannabis states were less likely to report driving high.

•

Users in recreational states were less likely to report driving high.

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Likelihood of driving high varied by frequency of cannabis use.

The relationship between cannabis legalization and traffic safety remains unclear. Physiological measures of cannabis impairment remain imperfect. This analysis used self-report data to examine the relationship between cannabis legalization and driving under the influence of cannabis (DUIC)1.

Using a cross-sectional national sample (2016–2017) of 1,249 past–30-day cannabis users, we regressed self-reported DUIC (driving within three hours of “getting high”) on cannabis legalization (recreational and medical (recreational), medical only (medical), or no legal cannabis), adjusting for demographics, days of use (past 30 days), days of use*legal status, calibration weights, and geographic clustering.

The risk of DUIC in recreational (risk ratio [RR] = 0.41, 95% confidence interval (CI):0.23–0.72) and medical (RR = 0.39, 95% CI:0.20–0.79) states was lower than in states without legal cannabis, with one exception. Among frequent cannabis users (≥20 days per month), there was a significantly lower risk of DUIC for those living in recreational states (RR = 0.70, 95% CI: 0.49–0.99), but not for those living in medical states (RR = 0.87, 95% CI: 0.60–1.24), compared to users living in states without legal cannabis.

The risk of self-reported DUIC was lower in recreational and medical cannabis states compared to states without legal cannabis. The only exception was for frequent users in medical states, for whom there was no difference in risk compared to frequent users living in states without legal cannabis.

An assessment of the non-fatal crash risks associated with substance use during rush and non-rush hour periods in the United States

BACKGROUND

Understanding how substance use is associated with severe crash injuries may inform emergency care preparedness.

OBJECTIVES

This study aims to assess the association of substance use and crash injury severity at all times of the day and during rush (6-9 AM; 3-7 PM) and non-rush-hours. Further, this study assesses the probabilities of occurrence of low acuity, emergent, and critical injuries associated with substance use.

METHODS

Crash data were extracted from the 2019 National Emergency Medical Services Information System. The outcome variable was non-fatal crash injury, assessed on an ordinal scale: critical, emergent, low acuity. The predictor variable was the presence of substance use (alcohol or illicit drugs). Age, gender, injured part, revised trauma score, the location of the crash, the road user type, and the geographical region were included as potential confounders. Partially proportional ordinal logistic regression was used to assess the unadjusted and adjusted odds of critical and emergent injuries compared to low acuity injury.

RESULTS

Substance use was associated with approximately two-fold adjusted odds of critical and emergent injuries compared to low acuity injury at all times of the day and during the rush and non-rush hours. Although the proportion of substance use was higher during the non-rush hour period, the interaction effect of rush hour and substance use resulted in higher odds of critical and emergent injuries compared to low acuity injury.

CONCLUSION

Substance use is associated with increased odds of critical and emergent injury severity. Reducing substance use-related crash injuries may reduce adverse crash injuries.

Estimating Cannabis Involvement in Fatal Crashes in Washington State Before and After the Legalization of Recreational Cannabis Consumption Using Multiple Imputation of Missing Values

The government of Washington state legalized recreational cannabis consumption in December 2012. We used data on all drivers involved in fatal crashes in Washington in the years 2008-2019 (n = 8,282) to estimate prevalence in fatal crashes of drivers with ∆9-tetrahydrocannabinol (THC; the main psychoactive compound in cannabis) in their blood before and after legalization. However, nearly half of the drivers were not tested for drugs; we therefore used multiple imputation to estimate THC presence and concentration among them. We used logistic regression followed by marginal standardization to estimate the adjusted prevalence of THC-positive drivers after legalization relative to what would have been predicted without legalization. In the combined observed and imputed data, the proportion of drivers positive for THC was 9.3% before and 19.1% after legalization (adjusted prevalence ratio: 2.3, 95% confidence interval: 1.3, 4.1). The proportion of drivers with high THC concentrations increased substantially (adjusted prevalence ratio: 4.7, 95% confidence interval: 1.5, 15.1). Some of the increased prevalence of THC-positive drivers might have reflected cannabis use unassociated with driving; however, the increased prevalence of drivers with high THC concentrations suggests an increase in the prevalence of driving shortly after using cannabis. Other jurisdictions should compile quantitative data on drug test results of drivers to enable surveillance and evaluation.

Trends in Cannabis Involvement and Risk of Alcohol Involvement in Motor Vehicle Crash Fatalities in the United States, 2000‒2018

Objectives. To assess cannabis and alcohol involvement among motor vehicle crash (MVC) fatalities in the United States. Methods. In this repeated cross-sectional analysis, we used data from the Fatality Analysis Reporting System from 2000 to 2018. Fatalities were cannabis-involved if an involved driver tested positive for a cannabinoid and alcohol-involved based on the highest blood alcohol concentration (BAC) of an involved driver. Multinomial mixed-effects logistic regression models assessed cannabis as a risk factor for alcohol by BAC level. Results. While trends in fatalities involving alcohol have remained stable, the percentage of fatalities involving cannabis and cannabis and alcohol increased from 9.0% in 2000 to 21.5% in 2018, and 4.8% in 2000 to 10.3% in 2018, respectively. In adjusted analyses, fatalities involving cannabis had 1.56 (95% confidence interval [CI] = 1.48, 1.65), 1.62 (95% CI = 1.52, 1.72), and 1.46 (95% CI = 1.42, 1.50) times the odds of involving BACs of 0.01% to 0.049%, 0.05% to 0.079%, and 0.08% or higher, respectively. Conclusions. The percentage of fatalities involving cannabis and coinvolving cannabis and alcohol doubled from 2000 to 2018, and cannabis was associated with alcohol coinvolvement. Further research is warranted to understand cannabis- and alcohol-involved MVC fatalities. (Am J Public Health. 2021;111(11):1976-1985. https://doi.org/10.2105/AJPH.2021.306466).

Interventions to Prevent Drugged Driving: A Systematic Review

CONTEXT

Literature suggests that cannabis legalization may increase fatal motor vehicle collisions. However, evidence on the effectiveness of interventions to prevent drugged driving is limited.

EVIDENCE ACQUISITION

MEDLINE, PsycINFO, Web of Science, Embase, SafetyLit, Criminal Justice Database, Transport Research International Documentation, bibliographies, and relevant gray literature were searched systematically through May 2020. Randomized and nonrandomized studies of preventive interventions measuring drugged driving outcomes were included. Evidence certainty was judged per Grading of Recommendations Assessment, Development, and Evaluation guidelines to designate quality ratings from very low to high.

EVIDENCE SYNTHESIS

The search identified 11 RCTs and 17 nonrandomized studies conducted predominantly among youth (aged 15-25 years; n=33,711 of 37,117 active research participants). In the public, cannabis packaging with health warnings increases the knowledge about drugged driving effects (high certainty); roadside drug testing can reduce drugged driving among cannabis users (moderate certainty); media campaigns may increase deterrent attitudes and knowledge (low certainty); and state sanctions, including traffic offense criminalization, license withdrawal, and per se drugged driving laws, may have little or no effect on drug-related fatalities or injuries (very low-low certainty). For youth or previous offenders, motivational interviewing can prevent drugged driving and driver education programs can increase knowledge (moderate certainty), whereas drug abuse prevention, substance abuse treatment, and driver rehabilitation may prevent drugged driving (very low certainty).

CONCLUSIONS

Overall, there is evidence to support the interventions that may improve drugged driving knowledge, attitudes, and behaviors. However, the impact of such interventions on measures of drugged driving-related morbidity and mortality is uncertain. Further research is urgently required to address these gaps in knowledge.

Blood and Oral Fluid Cannabinoid Profiles of Frequent and Occasional Cannabis Smokers

Increased prevalence of cannabis consumption and impaired driving are a growing public safety concern. Some states adopted per se driving laws, making it illegal to drive with more than a specified ∆9-tetrahydrocannabinol (THC) blood concentration of THC in a biological fluid (typically blood). Blood THC concentrations decrease significantly (~90%) with delays in specimen collection, suggesting use of alternative matrices, such as oral fluid (OF). We characterized 10 cannabinoids' concentrations, including THC metabolites, in blood and OF from 191 frequent and occasional users by LC-MS-MS for up to 6 h after ad libitum smoking. Subjects self-titrated when smoking placebo, 5.9 or 13.4% THC cannabis. Higher maximum blood THC concentrations (Cmax) were observed in individuals who received the 5.9% THC versus the 13.4% THC plant material. In blood, the Cmax of multiple analytes, including THC and its metabolites, were increased in frequent compared to occasional users, whereas there were no significant differences in OF Cmax. Blood THC remained detectable (≥5 ng/mL) at the final sample collection for 14% of individuals who smoked either the 5.9% or 13.4% THC cigarette, whereas 54% had detectable THC in OF when applying the same cutoff. Occasional and frequent cannabis users' profiles were compared, THC was detectable for significantly longer in blood and OF from frequent users. Detection rates between frequent and occasional users at multiple per se cutoffs showed larger differences in blood versus OF. Understanding cannabinoid profiles of frequent and occasional users and the subsequent impact on detectability with current drug per se driving limits is important to support forensic interpretations and the development of scientifically supported driving under the influence of cannabis laws.

Impact of Florida's prescription drug monitoring program on drug- related fatal vehicle crashes: a difference-in-differences approach

BACKGROUND

Prescription drug use has soared in the USA within the last two decades. Prescription drugs can impair motor skills essential for the safe operation of a motor vehicle, and therefore can affect traffic safety. As one of the epicentres of the opioid epidemic, Florida has been struck by high opioid misuse and overdose rates, and has concurrently suffered major threats to traffic disruptions safety caused by driving under the influence of drugs. To prevent prescription opioid misuse in Florida, Prescription Drug Monitoring Programs (PDMPs) were implemented in September 2011.

OBJECTIVE

To examine the impact of Florida's implementation of a mandatory PDMP on drug-related MVCs occurring on public roads.

METHODS

We employed a difference-in-differences approach to estimate the difference in prescription drug-related fatal crashes in Florida associated with its 2011 PDMP implementation relative to those in Georgia, which did not use PDMPs during the same period (2009-2013). The analyses were conducted in 2020.

RESULTS

In Florida, there was a significant decline in drug-related vehicle crashes during the 22 months post-PDMP. PDMP implementation was associated with approximately two (-2.21; 95% CI -4.04 to -0.37; p<0.05) fewer prescribed opioid-related fatal crashes every month, indicating 25% reduction in the number of monthly crashes. We conducted sensitivity analyses to investigate the impact of PDMP implementation on central nervous system depressants and stimulants as well as cocaine and marijuana-related fatal crashes but found no robust significant reductions.

CONCLUSIONS

The implementation of PDMPs in Florida provided important benefits for traffic safety, reducing the rates of prescription opioid-related vehicle crashes.

A mobile phone-based brief intervention with personalized feedback and interactive text messaging is associated with changes in driving after cannabis use cognitions in a proof-of-concept pilot trial

Driving after cannabis use (DACU) is a significant public health concern and represents one of the riskiest cannabis-related behaviors. Though years of research has demonstrated that cannabis use impairs driving ability, many college students report believing that cannabis use does not impair their driving abilities. This perception of low danger may contribute to a permissive attitude toward DACU. The present proof-of-concept pilot study examined the preliminary efficacy of a mobile phone-based intervention with personalized feedback and text messaging to increase perceptions of dangerousness of DACU. Participants were 77 college cannabis users (65.8% women; average age = 21.2; 88.3% Caucasian) who endorsed DACU at least three times in the past 3 months. After completing baseline measures, participants were randomly assigned to one of three conditions: (a) personalized feedback plus interactive text messaging (PFT), (b) personalized feedback only (PF), or (c) informational control (IC). Participants completed outcome measures 3 months post intervention. Repeated measures mixed models revealed that compared to those in the IC condition, cannabis users in the PFT condition reported significantly greater increases over time in the perception of dangerousness of DACU. These findings provide initial support for the short-term efficacy of a mobile phone-based intervention for changing perceptions related to dangerousness of DACU among college cannabis users. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Driving under the influence of drugs or alcohol: Predicting the intentions of young drivers

Objectives: Driving under the influence (DUI) of drugs or alcohol impairs driving performance and, as a result, increases the risk of crashes. The risk of DUI is five-fold higher for young drivers (aged 18-25 years), but little is known about what determines their DUI intentions. This study applied an extended model of the Theory of Planned Behavior (TPB) to address the research question of what factors might influence young drivers' future intentions to DUI. Methods: This study used a survey obtaining data from 329 young drivers (Mage = 20.92 years, SD = 2.16) in Australia. Beyond the standard TPB measures of attitudes, subjective norms and perceived behavioral control (PBC), the current study included demographic variables and additional predictors (i.e., moral norm, peers' norm, perceived risk, impulsivity and past DUI behavior). Results: A vast majority of the participants (85.1%) selected the maximum (9, never), meaning that they had no intention to DUI in the future. Overall, a stepwise multilevel logistic regression analysis (Step 1: demographics, Step 2: TPB measures, and Step 3: additional predictors) explained between 30.1% and 52.9% of the variance in DUI intentions. It showed past DUI behavior as the strongest predictor of DUI intention, followed by instrumental attitude and descriptive norms. Conclusions: This study explored an extended TPB model to understand young drivers' DUI intentions better. With this new knowledge of understanding the factors that influence DUI, researchers and practitioners can create interventions and strategies that are better tailored to the population of young drivers at higher risk.

Differential effects of stimulant versus opiate drugs on driving performance

BACKGROUND AND AIMS

Pharmacological differences among different drug classes influence human cognition, visual, and motor behavior in different ways. These differences impact driving safety, and therefore individuals who use stimulant and opioid drugs might experience different patterns in driving safety and impairment in driving performance. This study examined the effect of long-term use of stimulant drugs and of opiate drugs on driving performance, hazard perception, visual search skills and psychomotor skills related to driving.

METHODS

A total of 75 individuals, including 28 predominantly stimulant users, 22 predominantly opiate users and 25 healthy non-drug users, participated. Driving performance and psychomotor skills were assessed via a 15-minute drive in a simulator; hazard perception was assessed via a computerized task; and visual search skill was assessed by eye tracking.

RESULTS

ANOVA analyses indicate both stimulant and opiate users drove at higher speeds and experienced more crashes than the healthy non-drug users. Stimulant but not opiate users violated red light regulations more often than the healthy non-drug users. In the hazard perception task, stimulant drug users performed more poorly than both opioid drug users and healthy non-drug users. Specifically, they had lower saccade movement scores and higher average fixation times.

CONCLUSIONS

Results confirm that both stimulant drug users and opiate drug users show impaired driving performance compared to healthy non-drug users. Stimulant drug users possessed poorer hazard perception skills compared to the opiate users and the control group, perhaps as a result of cognitive deficits created by the drug use.

Opioid Use and Driving Performance

INTRODUCTION

The USA is in an opioid epidemic, with an increased number of individuals taking psychoactive drugs while executing the tasks of everyday life, including operating a motor vehicle. The pharmacology of opioids has been widely studied, but the effects of opioids on psychomotor function, driving performance, and the risk of motor vehicle collision remain less clear. Clinicians are faced with the challenge of controlling patient pain while also reconciling conflicting messages from the literature about how safe it is for their patients taking opioids to engage in potentially dangerous routine tasks.

DISCUSSION

This review assesses the current literature regarding opioids as they relate to neurocognitive function, driving performance, and accident risk. Manuscripts are categorized by study context and subject matter: controlled experimental administration, illicit use, prescription use, retrospective forensic toxicology, and polydrug consumption.

CONCLUSION

Illicit use, initiation of therapy, and opioid use in combination with other psychoactive medications are contexts most clearly associated with impairment of driving-related functions and/or operation of a motor vehicle. Clinicians should counsel patients on the risk of impairment when initiating therapy, when co-prescribing opioids and other psychoactive drugs, or when a patient is suspected of having an opioid use disorder.

Patterns, Consequences, and Motives in Simultaneous Use of Prescription Stimulant Medication with Alcohol and Marijuana

Nonmedical use of prescription stimulants (NPS) continues to be a concern on college campuses. Previous research demonstrates a strong link between NPS and use of other substances, particularly alcohol and marijuana among college students. Simultaneous use of NPS with other substances has become an increasing concern. Given the high rates of NPS and simultaneous NPS with other substances, research examining substance use patterns and motives among students is warranted. Method: This study evaluated group differences in alcohol and marijuana use patterns, consequences, and motives among college students: a) with no NPS history (No NPS); b) engaged in NPS with no simultaneous use (Non-Sim NPS); and c) engaged in simultaneous NPS with alcohol and/or marijuana (Sim NPS). Participants included 1,108 students from three universities who reported past-year marijuana and alcohol use. Results: Overall, 32.8% reported lifetime NPS with 12.5% indicating NPS in the previous 3 months, of which 51.1% reported simultaneous NPS with alcohol and 40.2% with marijuana. Significant group differences for all drinking and marijuana outcomes were found, with heaviest rates among the Sim NPS group, followed by the Non-Sim NPS group, and the No NPS group. The Sim NPS group reported greater motives for using marijuana to alter the effects of other substances. Conclusions: College students engaged in simultaneous NPS with alcohol and marijuana are a high-risk group that should be the focus of prevention and intervention programs in the campus setting.

Does the Combination Matter? Examining the Influence of Alcohol and Cannabis Product Combinations on Simultaneous Use and Consequences in Daily Life

BACKGROUND

Alcohol and marijuana/cannabis are frequently used simultaneously (i.e., SAM use). SAM use is complex, and the ways in which alcohol and cannabis are simultaneously used may reveal differential effects. The purpose of this study was to examine day-level effects of distinct alcohol and cannabis product combinations on simultaneous use and consequences on that day.

METHODS

College student SAM users (N = 274; 50% women; Mage  = 19.82 years) were recruited to complete 54 days of data collection, including 5 repeated daily surveys each day. We identified 12 distinct product combinations reported during SAM-use days. We tested 4 reference groups, with one reflecting the most common use pattern and 3 potentially risky use patterns. We considered 3 outcomes (negative consequences, number of drinks, and number of cannabis uses) and used generalized linear mixed-effects models disentangling within- from between-person effects in all analyses.

RESULTS

Using multiple products (≥2) of alcohol was consistently linked to higher odds of experiencing a negative consequence. Combining beer with only one cannabis product (leaf or concentrate) was consistently associated with lower odds of a consequence. Combining cannabis with multiple alcohol products was associated with heavier alcohol consumption. Using dual cannabis products also was associated with heavier cannabis consumption, but this pattern was not significantly different than using concentrate only on a given day.

CONCLUSION

This is the first study to examine day-level influences of distinct alcohol and cannabis product combinations on consumption and consequences among young adult SAM users. Findings suggest that mixing alcohol products confers greater risk for negative consequences and heavier consumption, whereas there is little difference in cannabis consumption when using concentrate only vs. 2 cannabis products on a given day, except for concentrate + beer. Our findings support existing protective strategies of not mixing alcohol products and avoiding use of cannabis concentrate for SAM use as well.

Impact of cannabis and low alcohol concentration on divided attention tasks during driving

OBJECTIVE

To assess divided-attention performance when driving under the influence of cannabis with and without alcohol. Three divided-attention tasks were performed following administration of placebo, cannabis, and/or alcohol.

METHODS

Healthy adult cannabis users participated in 6 sessions, receiving combinations of cannabis (placebo/low-THC/high-THC) and alcohol (placebo/active) in randomized order, separated by washout periods of ≥1 week. At 0.5 hours post-dosing, participants performed simulator drives in the University of Iowa National Advanced Driving Simulator (NADS-1), a full vehicle cab simulator with a 360° horizontal field of view and motion base that provides realistic feedback. Drives contained repeated instances of three tasks: a side-mirror task (reaction to a triangle appearing in the side-mirrors), an artist-search task (select a specified artist from a navigable menu on the vehicle's console), and a message-reading task (read aloud a message displayed on the console). Blood THC and breath alcohol concentration (BrAC) were interpolated using individual power curves from samples collected approximately 0.17, 0.42, 1.4, and 2.3 hours post-dose. Driving measures during tasks were compared to equal-duration control periods occurring just prior to the task. Performance shifts, task completion, and lane departures were modeled relative to blood THC and BrAC using mixed-effects regression models.

RESULTS

Each 1 µg/L increase in blood THC concentration predicted increased odds of failing to complete the artist-search task (OR: 1.05, 95% CI: 1.01-1.11, p = 0.046), increased odds of selecting at least one incorrect response (OR: 1.05, 95% CI: 1.00-1.09, p = 0.041), declines in speed during the side-mirror task (0.005 m/s, 95% CI: 0.001-0.009, p = 0.023), and longer lane departure durations during the artist-search task (0.74% of task-period, 95% CI: 0.12-1.36 p = 0.020). BrAC (approximately 0.05%) was not associated with task performance, though each 0.01 g/210 L increase predicted longer departure durations during the side-mirror task (1.41% of task-period, 95% CI: 0.08-2.76, p = 0.040) and increased standard deviation of lane position in the message-reading task (0.61 cm, 95% CI: 0.14-1.08, p = 0.011).

CONCLUSIONS

With increasing medical and legal cannabis use, understanding the impact of acute cannabis use on driving performance, including divided-attention, is essential. These data indicate that impaired divided-attention performance is a safety concern.

Cannabis-impaired driving and Canadian youth

Acute cannabis use results in inattention, delayed information processing, impaired coordination, and slowed reaction time. Driving simulator studies and epidemiologic analyses suggest that cannabis use increases motor vehicle crash risk. How much concern should we have regarding cannabis associated motor vehicle collision risks among younger drivers? This article summarizes why young, inexperienced drivers may be at a particularly high risk of crashing after using cannabis. We describe the epidemiology of cannabis use among younger drivers, why combining cannabis with alcohol causes significant impairment and why cannabis edibles may pose a heightened risk to traffic safety. We provide recommendations for clinicians counselling younger drivers about cannabis use and driving.

Is marijuana use associated with decreased use of prescription opioids? Toxicological findings from two US national samples of drivers

Background

State governments in the United States are increasingly viewing marijuana legalization as a policy option for controlling the opioid epidemic under the premise that marijuana is a less harmful substitute for opioids. The purpose of this study is to assess whether marijuana use is associated with decreased odds of prescription opioid use.

Methods

A cross-sectional study design was applied to toxicological testing data from two national samples of drivers: 1) the 2011–2016 Fatality Analysis Reporting System (FARS) and 2) the 2013–2014 National Roadside Survey of Alcohol and Drug Use by Drivers (NRS). Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) estimated from multivariable logistic regression models were used to assess the associations of marijuana use with prescription opioid use and alcohol use.

Results

Among the 47,602 drivers from the FARS, 15.7% tested positive for marijuana and 6.9% positive for prescription opioids. Compared with drivers testing negative for marijuana, those testing positive for marijuana were 28% more likely to test positive for prescription opioids (adjusted OR = 1.28, 95% CI = 1.15–1.42). Among the 7881 drivers from the NRS, 7.9% tested positive for marijuana and 4.5% positive for prescription opioids. Relative to drivers testing negative for marijuana, those testing positive for marijuana were twice as likely to test positive for prescription opioids (adjusted OR = 2.03, 95% CI = 1.29–3.20). In both study samples, marijuana use was associated with significantly increased odds of alcohol positivity.

Conclusions

Drivers who test positive for marijuana are significantly more likely to test positive for prescription opioids. Longitudinal studies with rigorous designs and toxicological testing data are needed to further address the substitution hypothesis between marijuana and prescription opioids.

Alcohol and illicit substances associated with fatal crashes in Queensland: An examination of the 2011 to 2015 Coroner's findings

PROBLEM

The problem of impaired driving is well documented in the literature but is heavily dependent upon self-report studies and/or databases that do not include in-depth information about the contributing origins of fatalities.

AIM

This study aimed to conduct an in-depth analysis of Coroner's findings for all fatally injured drivers in the state of Queensland in order to explore the prevalence of alcohol and different types of illicit substances (including drug combinations) in fatal crash reports.

METHOD

A total of 701 Coroner's reports related to drivers or controllers of vehicles involved in traffic related fatalities for the period of 2011-2015 were analysed, revealing 306 controllers (43.6%) were detected with either alcohol or illegal drugs (e.g., methylamphetamine, Δ9-tetrahydrocannabinol, cocaine or MDMA) RESULTS: Alcohol was the most commonly detected substance identified with 223 cases (72.9% of the drug and alcohol sample). Illicit drug detections totalled 147 cases (48% of the drug and alcohol sample) with Δ9-tetrahydrocannabinol the most commonly detected illicit substance (109 cases; 35.6% of the drug and alcohol sample) followed by methylamphetamine (total of 63 cases; 20.6% of the drug and alcohol sample). An important theme to emerge was the prevalence of polysubstance use among fatally injured drivers, not just for alcohol and one drug type, but also multiple drug combinations. Fatality trends revealed a decrease in both non-substance and alcohol-related fatalities across the study period. However, road fatalities where an illicit substance was detected increased by approximately 57%. Males were overrepresented as a proportion of total fatalities (82.4%) and there were no significant sex or age differences regarding illicit substance related deaths. Drivers of passenger vehicles were most commonly identified in the data (66.2%), but motorcycle operators were disproportionately represented (28.1% of the total controller sample compared to 4% of vehicle registrations in Queensland) CONCLUSION: This case study analysis of fatal crashes not only confirms the ongoing problem of alcohol and driving, but also illuminates the emerging (and escalating) issue of illicit substances detected in fatally injured drivers.

Odds of culpability associated with use of impairing drugs in injured drivers in Victoria, Australia

Culpability analysis was conducted on 5000 drivers injured as a result of a vehicular collision and in whom comprehensive toxicology testing in blood was conducted. The sample included 1000 drivers for each of 5 years from approximately 5000-6000 drivers injured and taken to hospital in the State of Victoria. Logistic regression was used to investigate differences in the odds of culpability associated with alcohol and drug use and other selected crash attributes using the drug-free driver as the reference group. Adjusted odds ratios were obtained from multivariable logistic regression models in which other potentially explanatory driver and crash attributes were included. Drivers with alcohol present showed large increases in the odds of culpability similar to that seen in other studies investigating associations between blood alcohol concentration and crash risk. Methylamphetamine also showed a large increase in the odds of culpability (OR 19) compared to the reference group at both below and above 0.1 mg/L, whereas those drivers with Δ⁹-tetrahydrocannabinol (THC) present showed only modest increase in odds when all concentrations were assessed (OR 1.9, 95 %CI 1.2-3.1). Benzodiazepines in drivers also gave an increase in odds (3.2, 95 %CI 1.6-6.1), but not other medicinal drugs such as antidepressants, antipsychotics and opioids. Drivers that had combinations of impairing drugs generally gave a large increase in odds, particularly combinations of alcohol with THC or benzodiazepines, and those drivers using both THC and methamphetamine.

Cannabinoid Stability in Antemortem and Postmortem Blood

In toxicological testing, drug stability is important when providing quantitative results and interpretation of findings, as well as when collecting correlation data. The goal of this study was to expand on previous stability studies and to evaluate other cannabinoids encountered in forensic toxicology. In this 6-month study, the stability of Δ-9-tetrahydrocannabinol (THC), 11-hydroxy-THC, 11-nor-9-carboxy-THC, Cannabinol and Cannabidiol in antemortem and postmortem blood was evaluated in refrigerated (4°C) and frozen (−4°C) storage conditions. Pooled antemortem and postmortem bloods were fortified at low and high concentrations and stored in untreated glassware. Over 6 months, samples were analyzed by automated extraction and liquid chromatography-mass spectrometry/mass spectrometry to evaluate the change in concentration over time. Samples in each storage condition were analyzed in triplicate 12 times over the 6-month period. Cannabinoids in antemortem blood were more stable in the refrigerated condition than in the frozen condition, with 11-hydroxy-THC, 11-nor-9-carboxy-THC and Cannabinol having more than 80% of the original concentration remaining at the end of the study. Cannabinoids in postmortem blood had improved stability in the frozen storage condition with THC, 11-hydroxy-THC, 11-nor-9-carboxy-THC and Cannabinol in the low concentration pool with more than 80% of the original concentration remaining. These data demonstrated that cannabinoids may decrease in concentration over time when stored in untreated glass vials. To ensure the most accurate determination of drug concentration, samples containing cannabinoids should be analyzed as soon as possible.

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.

Cannabis use as a risk factor for causing motor vehicle crashes: a prospective study

AIM

We conducted a responsibility analysis to determine whether drivers injured in motor vehicle collisions who test positive for Δ-9-tetrahydrocannabinol (THC) or other drugs are more likely to have contributed to the crash than those who test negative.

DESIGN

Prospective case-control study.

SETTING

Trauma centres in British Columbia, Canada.

PARTICIPANTS

Injured drivers who required blood tests for clinical purposes following a motor vehicle collision.

MEASUREMENTS

Excess whole blood remaining after clinical use was obtained and broad-spectrum toxicology testing performed. The analysis quantified alcohol and THC and gave semiquantitative levels of other impairing drugs and medications. Police crash reports were analysed to determine which drivers contributed to the crash (responsible) and which were 'innocently involved' (non-responsible). We used unconditional logistic regression to determine the likelihood (odds ratio: OR) of crash responsibility in drivers with 0 < THC < 2 ng/ml, 2 ng/ml ≤ THC < 5 ng/ml and THC ≥ 5 ng/ml (all versus THC = 0 ng/ml). Risk estimates were adjusted for age, sex and presence of other impairing substances.

FINDINGS

We obtained toxicology results on 3005 injured drivers and police reports on 2318. Alcohol was detected in 14.4% of drivers, THC in 8.3%, other drugs in 8.9% and sedating medications in 19.8%. There was no increased risk of crash responsibility in drivers with THC < 2 ng/ml or 2 ≤ THC < 5 ng/ml. In drivers with THC ≥ 5 ng/ml, the adjusted OR was 1.74 [95% confidence interval (CI) = 0.59-6.36; P = 0.35]. There was significantly increased risk of crash responsibility in drivers with blood alcohol concentration (BAC) ≥ 0.08% (OR = 6.00;95% CI = 3.87-9.75; P < 0.01), other recreational drugs detected (OR = 1.82;95% CI = 1.21-2.80; P < 0.01) or sedating medications detected (OR = 1.45; 95%CI = 1.11-1.91; P < 0.01).

CONCLUSIONS

In this sample of non-fatally injured motor vehicle drivers in British Columbia, Canada, there was no evidence of increased crash risk in drivers with Δ-9-tetrahydrocannabinol < 5 ng/ml and a statistically non-significant increased risk of crash responsibility (odds ratio = 1.74) in drivers with Δ-9-tetrahydrocannabinol ≥ 5 ng/ml.

Incidence of fatalities of road traffic accidents associated with alcohol consumption and the use of psychoactive drugs: A 7-year survey (2011-2017)

Driving under the influence of alcohol and/or psychoactive substances increases the risk of severe, even fatal motor vehicle accidents. The aim of this descriptive study was to present the impact of alcohol and/or psychoactive substances on fatal road traffic accidents (RTAs) during the period 2011-2017. For this purpose, the toxicological investigation reports from the Department of Forensic Medicine and Toxicology of the University of Athens were used. In total, 1,841 (32.2%) of the autopsies conducted by the Department of Forensic Medicine and Toxicology of the National and Kapodistrian University of Athens over a 7-year period (2011-2017) were victims of fatal RTAs. Blood and urine samples were collected and analyzed for the presence of alcohol and psychoactive substances. The results were classified according to sex, age, victim (car driver, motorcyclist, pedestrian, or passenger) and the date the accident occurred (day, month and year). In total, 40.7% of the RTA-related fatalities were associated with alcohol consumption, among which 20.3% were car drivers. Of these, 87.3% were male victims. A higher frequency of RTA-related fatalities associated with a blood alcohol concentration (BAC) >110 mg/dl was encountered in younger compared with older age groups. Psychoactive substances were detected in 348 (18.9%) of the victims (cannabis in 46.6% of these, benzodiazepines in 25.9%, opiates in 16.4% and cocaine in 11.1% of these). The percentage of the RTA-related victims that had consumed alcohol in combination with other psychoactive substances was 4.5%. On the whole, the findings of this study suggest that alcohol and psychoactive substances are probably risk factors for RTA-related fatalities.

Substance use and impaired driving prevalence among Francophone and Anglophone postsecondary students in Western Canada

INTRODUCTION

Substance use and impaired driving increase risk of motor vehicle crashes and deaths. Individual, socio-economic and -cultural factors are associated with these at-risk behaviors; however, little is known if differences exist between the Anglophone majority and minority Francophone populations in Canada. This article describes prevalence of substance use, impaired driving and driving practices by postsecondary student and compares Francophones and Anglophones with respect to these behaviors.

METHODS

Postsecondary students between 18 and 24 years attending a Francophone university in Western Canada completed a paper-based survey during class-time.

RESULTS

Prevalence of alcohol consumption, binge drinking and marijuana use in the past month were 88.6%, 64.2% and 22.7% respectively. Francophone participants were more likely to consume more alcohol, participate in drinking games, and consume marijuana during the past month than Anglophones. They were also more likely to report impaired-driving, speeding, distracted driving and being passenger in a motor vehicle driven by an impaired driver.

CONCLUSION

Awareness campaigns on campus highlighting the risks of substance use and unsafe driving practices should be strengthened and target Francophone students in linguistic minority communities.

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.

Trends and correlates of driving under the influence of alcohol among different types of adult substance users in the United States: a national survey study

Background

Despite a decrease in driving under the influence of alcohol (DUIA) prevalence over the past decades, DUIA prevalence still remains high in the United States. To date, there is limited research examining whether different types of substance users have different trends in DUIA. This study sought to assess trends and variables associated with DUIA by substance use type.

Methods

National Survey on Drug Use and Health (NSDUH) is a cross-sectional, nationally representative population-based survey. By using the NSDUH 2008–2014, we performed the Joinpoint analysis to identify time trends of DUIA in each group of substance users (aged ≥18 years). Logistic regression analysis was used to explore association between substance use type and DUIA and to identify variables associated with DUIA.

Results

Adults who reported alcohol or drug use in the past year were classified into different groups based on past-year substance use status: alcohol use only (n = 141,521) and drug use regardless alcohol use. Drug users included prescription opioids only (n = 5337), marijuana only (n = 32,206), other single drug (n = 3789), prescription opioids-marijuana (n = 3921), multiple prescription drugs (n = 1267), and other multiple drugs (n = 18,432). The Joinpoint analysis showed that DUIA prevalence decreased significantly from 2008 to 2014 among alcohol only users (Average Annual Percent Change [AAPC] = − 2.8), prescription opioids only users (AAPC = -5.4), marijuana only users (AAPC = -5.0), prescription opioids-marijuana users (AAPC = -6.5), multiple prescription drug users (AAPC = -7.4), and other multiple drug users (AAPC = -3.2). Although the estimate was not statistically significant, other single drug users showed a decreasing trend (AAPC = -0.9). Substance use type was significantly associated with DUIA in the adjusted logistic regression. All drug use groups, relative to the alcohol only group, had elevated odds of DUIA, and the odds were especially elevated for the multiple drug use groups (prescription opioids-marijuana, adjusted odds ratio [AOR] = 2.71; multiple prescription drugs, AOR = 2.83; and other multiple drugs, AOR = 3.68). Additionally, younger age, male sex, being white, higher income, and alcohol abuse/dependence were positively associated with DUIA.

Conclusions

DUIA prevalence decreased over time and the magnitude of this reduction differed by substance use type. DUIA interventions need to be tailored to substance use type and individual characteristics.

Geographic variation and trends in opioid-involved crash deaths in Maryland: 2006-2017

The objective of this study was to describe trends in the prevalence of opioids in driver fatalities and examine geographic variation in opioid-involved crashes at a county level. Using comprehensive toxicological data from the Office of the Chief Medical Examiner in Maryland, we examined the prevalence of opioids in all motor vehicle crash fatalities in Maryland between 2006-2017 and tested for trends to assess the statistical significance of changes in the prevalence of prescription opioids detected in these drivers over time. Opioid-involved crash deaths accounted for 10.0% of all driver deaths during the study period. The prevalence of opioids detected in fatally injured drivers increased from 8.3% in 2006 to 14.1% in 2017, (Z = -1.9, p < .05). The trends in opioid deaths do not follow broader trends in motor vehicle crash deaths; opioid-involved crashes appear to be increasing while overall motor vehicle crashes appear to be decreasing over the same period. To determine if the increase in opioid-involved crash deaths was the result of changes in pain management related to injuries sustained from the crash, we analyzed a subgroup of cases where death occurred at the scene of the crash. Within this group, there was no statistically significant increase in opioid-involved crashes during the study period. Opioid prevalence was higher in middle aged, and white drivers, and in crashes occurring in rural counties. Geographic distribution of opioid-involved crash deaths reflect broader patterns of opioid deaths overdose across the state. Irrespective of the timing of the deaths, of the drivers testing positive for opioids, 28% had elevated blood alcohol concentrations (‡ 0.01 g/dL), and 45% tested positive for other drugs.

Prescription opioids, alcohol and fatal motor vehicle crashes: a population-based case-control study

Background

The prevalence of prescription opioid use among drivers has increased markedly in the past two decades. The purpose of this study is to assess the associations of prescription opioid use and alcohol use with the risk of fatal crash involvement in US drivers.

Methods

We performed a population-based case-control study using toxicological testing data from two national data systems. Cases (n = 3606) were drivers involved in fatal motor vehicle crashes selected from the Fatality Analysis Reporting System and controls (n = 15,600) were drivers participating in the 2007 and 2013 National Roadside Surveys of Alcohol and Drug Use by Drivers. Multivariable logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs) of fatal crash involvement associated with prescription opioid use with and without the presence of alcohol.

Results

Overall, cases were significantly more likely than controls to test positive for prescription opioids (5.0% vs. 3.7%, p < 0.001), alcohol (56.2% vs. 7.1%, p < 0.0001), and both substances (2.2% vs. 0.2%, p < 0.001). Relative to drivers testing negative for prescription opioids and alcohol, the adjusted ORs of fatal crash involvement were 1.72 (95% CI: 1.37, 2.17) for those testing positive for prescription opioids and negative for alcohol, 17.92 (95% CI: 16.19, 19.84) for those testing positive for alcohol and negative for prescription opioids, and 21.89 (95% CI: 14.38, 33.32) for those testing positive for both substances. The interaction effect on fatal crash risk of prescription opioid use and alcohol use was not statistically significant on either additive or multiplicative scale.

Conclusions

Prescription opioid use is associated with a significantly increased risk of fatal crash involvement independently of alcohol use. Concurrent use of prescription opioids and alcohol is associated with a 21-fold increased risk of fatal crash involvement.

Use of Prescription Opioids and Initiation of Fatal 2-Vehicle Crashes

IMPORTANCE

The prevalence of prescription opioids detected in fatally injured drivers has increased markedly in the past 2 decades in the United States. It is unclear whether driver use of prescription opioids plays a role in fatal crash causation.

OBJECTIVE

To assess the association between driver use of prescription opioids and the risk of being culpable of crash initiation in fatal 2-vehicle crashes.

DESIGN, SETTING, AND PARTICIPANTS

This pair-matched study was based on data from the Fatality Analysis Reporting System for drivers involved in fatal 2-vehicle crashes on US public roads between January 1, 1993, and December 31, 2016. Data analysis was conducted from December 8, 2017, to December 7, 2018.

EXPOSURES

Testing positive for prescription opioids compared with testing negative, and blood alcohol concentrations (BACs) based on toxicological testing results.

MAIN OUTCOMES AND MEASURES

Culpability of crash initiation and adjusted odds ratios and 95% CIs.

RESULTS

A total of 36 642 drivers involved in 18 321 fatal 2-vehicle crashes were included. The most common driving error leading to fatal 2-vehicle crashes was failure to keep in lane (7535 [41%]). Drivers culpable of initiating the crashes were more likely than their nonculpable counterparts to test positive for prescription opioids (918 [5.0%] vs 549 [3.0%]; P < .001), alcohol (BAC ≥0.01 g/dL, 5258 [28.7%] vs 1815 [9.9%]; P < .001), and both substances (1.0% vs 0.3%, P < .001). The adjusted odds ratio of crash initiation was 2.18 (95% CI, 1.91-2.48) for drivers testing positive for prescription opioids compared with drivers testing negative, and increased with BACs (BAC 0.01-0.07 g/dL: adjusted odds ratio, 1.97; 95% CI, 1.75-2.22; BAC ≥0.08 g/dL: adjusted odds ratio, 8.20; 95% CI, 7.42-9.07; compared with BAC <0.01 g/dL). There was no significant interaction effect on crash initiation between prescription opioid use and alcohol use.

CONCLUSIONS AND RELEVANCE

Driver use of prescription opioids was associated with initiation of 2-vehicle crashes, independent of alcohol use. Clinicians should take into consideration the adverse effect of opioid analgesics on driving safety while prescribing these medications and counseling patients.

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.

Use of multiple data sources to identify specific drugs and other factors associated with drug and alcohol screening of fatally injured motor vehicle drivers

OBJECTIVE

Drugged driving crashes have significantly increased over the past two decades. The objectives of this study were to identify and characterize the drugs present in motor vehicle driver fatalities using multiple surveillance data sources; assess concordance of the data sources in identifying drug presence; and identify demographic and crash factors associated with drug and alcohol screening in fatally injured motor vehicle drivers.

METHODS

Fatality Analysis Reporting System (FARS), Collision Report Analysis for Safer Highways (CRASH), and mortality data sets were linked; drug screening and positive drug screens were identified. Chi-square and conditional logistic regression were performed.

RESULTS

The use of FARS data identified the majority of positive drug screens in the linked data set. Supplementation of FARS data with death certificate and CRASH data increased identification of specific drugs and drug classes detected among fatally injured motor vehicle drivers, although there was a low concordance among the data sources. Alcohol and depressants such as alprazolam had the highest frequencies among fatally injured drivers. Speeding, lack of occupant restraints, young age, commercial truck drivers, and speeding were all factors associated with increased odds of the fatally injured driver being drug or alcohol screened.

CONCLUSIONS

These findings indicate that FARS drug information data may be strengthened through increased autopsy and consultation with medical examiners to better understand and interpret decedent toxicology testing results, and that states with low driver drug testing rates should consider mandatory driver drug testing in fatal crashes.

Challenges in studying statewide pedestrian injuries and drug involvement

BACKGROUND

Increasing U.S. rates of pedestrian injuries could be attributable in part to changing policies and attitudes towards drugs and associated increases in use, yet drug use has not been investigated widely as a risk factor for pedestrian injury. This study details challenges to investigating drug-involved pedestrian crashes using existing surveillance systems.

METHODS

Using California police reports from 2004 to 2016, we performed simple linear regression with the proportion of data that was missing by year for drug and alcohol use as the outcome of interest. We also explored differences in the relative proportion of missing data across sex, race, and age groups through simple logistic regression. Finally, we compared missing data for alcohol and drug use indicators for pedestrians and drivers.

RESULTS

From 2004 to 2016, 182,278 pedestrians were involved in crashes across California. Only 1.22% (n = 2219) of records indicated drug use, and 98% had missing data for drug use; the proportion of missing data did not change over time (b = - 0.040, p = 0.145, 95% CI = (- 0.095, 0.016)). The proportion of missing values for alcohol use increased each year (b = 0.49, 95% CI = (0.26, 0.72), p = 0.001). Driver drug and alcohol use indictors showed similar data missingness, and missing data did not show significant variation over time. Hispanics were more likely to have missing data for drug use compared to Whites (OR = 0.61, p < 0.001, 95% CI = (0.56, 0.67)), and Blacks were more likely to have missing data for alcohol use compared to Whites (OR = 0.87, p < 0.0001, 95% CI = (0.84, 0.91)).

CONCLUSIONS

Drug use may be a key contributing factor to pedestrian injury, but drug use remains consistently and largely unmeasured in existing surveillance systems. Without better collection of drug and alcohol data, monitoring trends in drug-involved pedestrian injury will not be feasible.

Multiple imputation of missing marijuana data in the Fatality Analysis Reporting System using a Bayesian multilevel model

BACKGROUND

The Fatality Analysis Reporting System (FARS) provides important data for studying the role of marijuana in motor vehicle crashes. However, marijuana testing data are available for only 34% of drivers in the FARS, which represents a major barrier in the use of the data.

METHODS

We developed a multiple imputation (MI) procedure for estimating marijuana positivity among drivers with missing marijuana test results, using a Bayesian multilevel model that allows a nonlinear association with blood alcohol concentrations (BACs), accounts for correlations among drivers in the same states, and includes both individual-level and state-level covariates. We generated 10 imputations for the missing marijuana-testing data using Markov chain Monte Carlo simulations and estimated positivity rates of marijuana in the nation and each state.

RESULTS

Drivers who were at older age, female, using seatbelt at the time of crash, having valid license, or operating median/heavy trucks were less likely to test positive for marijuana. There was a reverse U-shaped association between BACs and positivity of marijuana, with lower positivity when BACs < 0.01 g/dL or ≥0.15 g/dL. The MI data estimated a lower positivity rate of marijuana in the nation and each of the state than the observed data, with a national positivity rate of 11.7% (95% CI: 11.1, 12.4) versus 14.8% using the observed data in 2013.

CONCLUSIONS

Our MI procedure appears to be a valid approach to addressing missing marijuana data in the FARS and may help strengthen the capacity of the FARS for monitoring the epidemic of drugged driving and understanding the role of marijuana in fatal motor vehicle crashes in the United States.