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

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.

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.

Driving under the influence of alcohol and drugs in the eastern part of Denmark in 2015 and 2016: Abuse patterns and trends

OBJECTIVES

The objective of this study was to examine the frequency of psychoactive drugs and alcohol in drivers under suspicion of driving under the influence of drugs and alcohol in 2015 and 2016 in the eastern part of Denmark. The trends in the number of traffic cases sent for drug analysis since 2000 and alcohol analysis since 2011 are also discussed.

METHODS

Blood samples from drivers suspected of being under the influence of alcohol and/or medication and/or illicit drugs in 2015 and 2016 were investigated as requested by the police. The blood samples were screened for alcohol and/or tetrahydrocannabinol (THC) alone, for other drugs (covering all drugs, except THC, listed in the Danish list of narcotic drugs), or for THC and other drugs. Age and gender were also recorded. The number of drug traffic cases since 2000 and the number of alcohol cases since 2011 were extracted from our Laboratory Information Management System (LIMS).

RESULTS

In total, 11,493 traffic cases were investigated. Alcohol and/or drugs exceeded the legal limit in 9,657 (84%) cases. Men constituted 95% of the drivers investigated for drugs and 88% of the alcohol cases. The drivers investigated for drugs consisted primarily of young men, whereas drivers investigated for alcohol were older. The frequency was higher for positive alcohol cases above the legal limit (87%) than for drug cases (76%) above the fixed concentration limit. THC (67-69%) was the most frequently detected drug above the legal limit, followed by cocaine (27-28.5%), amphetamine (17%), and clonazepam (6-7%) in both years. Morphine (5.4%), included among the 5 most frequent drugs in 2015, was replaced by methadone (4.6%) in 2016. Few new psychoactive drugs (NPS) were detected. The number of traffic cases sent for drug analysis has increased more than 30-fold since 2000-2006, and the number of traffic cases submitted in 2016 for drug analysis was higher than the number for alcohol analysis; the latter has decreased since 2011.

CONCLUSION

Overall, alcohol was the most frequent compound detected above the legal limit in both years, followed by the well-known illicit drugs THC, cocaine, and amphetamine. NPS were seldom seen. One consequence of the increased focus on drugs in traffic has been an immense increase in drug traffic cases sent for analysis since 2006 in the eastern part of Denmark. Although this survey revealed only minimal changes compared to earlier investigations, surveys like this are invaluable for monitoring abuse patterns and trends in drugged and drunken driving.

Ability to monitor driving under the influence of marijuana among non-fatal motor-vehicle crashes: An evaluation of the Colorado electronic accident reporting system

INTRODUCTION

As more states legalize medical/recreational marijuana use, it is important to determine if state motor-vehicle surveillance systems can effectively monitor and track driving under the influence (DUI) of marijuana. This study assessed Colorado's Department of Revenue motor-vehicle crash data system, Electronic Accident Reporting System (EARS), to monitor non-fatal crashes involving driving under the influence (DUI) of marijuana.

METHODS

Centers for Disease Control and Prevention guidelines on surveillance system evaluation were used to assess EARS' usefulness, flexibility, timeliness, simplicity, acceptability, and data quality. We assessed system components, interviewed key stakeholders, and analyzed completeness of Colorado statewide 2014 motor-vehicle crash records.

RESULTS

EARS contains timely and complete data, but does not effectively monitor non-fatal motor-vehicle crashes related to DUI of marijuana. Information on biological sample type collected from drivers and toxicology results were not recorded into EARS; however, EARS is a flexible system that can incorporate new data without increasing surveillance system burden.

CONCLUSIONS

States, including Colorado, could consider standardization of drug testing and mandatory reporting policies for drivers involved in motor-vehicle crashes and proactively address the narrow window of time for sample collection to improve DUI of marijuana surveillance. Practical applications: The evaluation of state motor-vehicle crash systems' ability to capture crashes involving drug impaired driving (DUID) is a critical first step for identifying frequency and risk factors for crashes related to DUID.

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

[This corrects the article on p. 99 in vol. 9, PMID: 29487531.].

Developing a theoretical foundation to change road user behavior and improve traffic safety: Driving under the influence of cannabis (DUIC)

OBJECTIVES

This study explored a theoretical model to assess the influence of culture on willingness and intention to drive under the influence of cannabis (DUIC). This model is expected to guide the design of strategies to change future DUIC behavior in road users.

METHODS

This study used a survey methodology to obtain a nationally representative sample (n = 941) from the AmeriSpeak Panel. Survey items were designed to measure aspects of a proposed definition of traffic safety culture and a predictive model of its relationship to DUIC.

RESULTS

Although the percentage of reported past DUIC behaviors was relatively low (8.5%), this behavior is still a significant public health issue-especially for younger drivers (18-29 years), who reported more DUIC than expected. Findings suggest that specific cultural components (attitudes, norms) reliably predict past DUIC behavior, general DUIC willingness, and future DUIC intention. Most DUIC behavior appears to be deliberate, related significantly to willingness and intention. Intention and willingness both appear to fully moderate the relationship between traffic safety culture and DUIC behavior.

CONCLUSIONS

This study explored a theoretical model to understand road user behavior involving drug (cannabis)-impaired driving as a significant risk factor for traffic safety. By understanding the cultural factors that increase DUIC behavior, we can create strategies to transform this culture and sustain safer road user behavior.

Marijuana and the Risk of Fatal Car Crashes: What Can We Learn from FARS and NRS Data?

Lab studies have shown that marijuana can severely impair driving skills. Epidemiological studies, however, have been inconclusive regarding the contribution of marijuana use to crash risk. In the United States, case-control studies based on the merging of comparable crash Fatality Analysis Reporting System (FARS) and non-crash National Roadside Survey (NRS) data have been applied to assess the contribution of drugs to crash risk, but these studies have yielded confusing, even contradictory results. We hypothesize that such a divergence of results emanates from limitations in the databases used in these studies, in particular that of the FARS. The goal of this effort is to examine this hypothesis, and in doing so, illuminate the pros and cons of using these databases for drugged-driving research efforts. We took advantage of two relatively recent cannabis crash risk studies that, despite using similar databases (the FARS and the NRS) and following similar overall approaches, yielded opposite results (Li, Brady, & Chen, 2013; Romano, Torres-Saavedra, Voas, & Lacey, 2014). By identifying methodological similarities and differences between these efforts, we assessed how the limitations of the FARS and NRS databases contributed to contradictory and biased results. Because of its limitations, we suggest that the FARS database should neither be used to examine trends in drug use nor to obtain precise risk estimates. However, under certain conditions (e.g., based on data from jurisdictions that routinely test for drugs, with as little variation in testing procedures as possible), the FARS database could be used to assess the contribution of drugs to fatal crash risk relative to other sources of risk such as alcohol.

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; [corrected] 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.

Driving and riding under the influence of recent marijuana use: Risk factors among a racially diverse sample of young adults

Driving (DUIM) and riding (RUIM) with a driver under the influence of marijuana increases crash risk. This study assessed risk factors for DUIM and RUIM among ethnically diverse young adults. Randomly selected individuals were surveyed. Multivariable regression was used to assess risk factors associated with DUIM and RUIM. Participants (N = 335, response rate = 34.9%) were 33.7% White non-Hispanic. Reported DUIM and RUIM was not statistically significant by race/ethnicity. Frequency of marijuana use was significantly associated with greater risk of DUIM. Peer marijuana use was associated with greater risk of RUIM. Public health efforts to target social norms around marijuana-impaired driving are warranted.

A latent class analysis of poly-marijuana use among young adults

INTRODUCTION

With more states legalizing marijuana use, the marijuana industry has grown, introducing a variety of marijuana products. Our study explores the use of multiple marijuana products (poly-marijuana use) and the characteristics associated with this behavior.

METHODS

Past-month marijuana users aged 18-34years were surveyed online via an existing online panel (n=2444). Participants answered questions about past-month use of three types of marijuana (plant-based, concentrates, edibles), marijuana use patterns, and driving after use. Latent class analysis was used to identify subgroups of marijuana users.

RESULTS

Four classes of marijuana users were identified: Light plant users, who used only plant-based products infrequently and were unlikely to drive after use (32%); Heavy plant users, who used mainly plant-based products frequently, multiple times per day, and were likely to drive after use (37%); Plant and concentrates users, who used plant-based products heavily and concentrates at least infrequently, used multiple times per day, and were likely to drive after use (20%); Light plant and edibles users, who used both products infrequently and were unlikely to drive after use (10%). Those in legal marijuana states were more likely to belong to the poly-marijuana groups.

DISCUSSION

Our findings reflect the increase in popularity of new marijuana products in legal states and suggest that heavy user groups, including concentrates users, are associated with driving after use. As various forms of marijuana use increases, monitoring and surveillance of the use of multiple types of marijuana will be important for determining potential varying impacts on physiological and social consequences.

Interaction of marijuana and alcohol on fatal motor vehicle crash risk: a case-control study

BACKGROUND

Concurrent use of marijuana and alcohol in drivers is of increasing concern but its role in crash causation has not been well understood.

METHODS

Using a case-control design, we assessed the individual and joint effects of marijuana and alcohol use on fatal crash risk. Cases (n = 1944) were drivers fatally injured in motor vehicle crashes in the United States at specific times in 2006, 2007 and 2008. Controls (n = 7719) were drivers who participated in the 2007 National Roadside Survey of Alcohol and Drug Use by Drivers.

RESULTS

Overall, cases were significantly more likely than controls to test positive for marijuana (12.2% vs. 5.9%, p < 0.0001), alcohol (57.8% vs. 7.7%, p < 0.0001) and both marijuana and alcohol (8.9% vs. 0.8%, p < 0.0001). Compared to drivers testing negative for alcohol and marijuana, the adjusted odds ratios of fatal crash involvement were 16.33 [95% confidence interval (CI): 14.23, 18.75] for those testing positive for alcohol and negative for marijuana, 1.54 (95% CI: 1.16, 2.03) for those testing positive for marijuana and negative for alcohol, and 25.09 (95% CI: 17.97, 35.03) for those testing positive for both alcohol and marijuana.

CONCLUSIONS

Alcohol use and marijuana use are each associated with significantly increased risks of fatal crash involvement. When alcohol and marijuana are used together, there exists a positive synergistic effect on fatal crash risk on the additive scale.

Continuity of drunk and drugged driving behaviors four years post-college

BACKGROUND

Driving under the influence of alcohol is a leading cause of injury and premature death among young adults, and college-educated individuals are at particularly high risk. Less is known about driving under the influence of other drugs, which is on the rise.

METHOD

This study describes prospective seven-year trends in alcohol and other drug (AOD)-involved driving among a young-adult sample beginning with their second year of college (i.e., Years 2-8), and documents the extent of continuity in such behaviors across time. Originally recruited as incoming first-year students at one large public university, participants (n=1194) were interviewed annually about how frequently they drove while drunk/intoxicated (DWI), after drinking any alcohol (DAD), and/or while under the influence of other drugs (DD). Follow-up rates were high (>75% annually).

RESULTS

Among participants with access to drive a car, annual prevalence peaked in Year 4 (modal age 21) for both DWI (24.3%_wt) and DD (19.1%_wt) and declined significantly thereafter through Year 8 (both ps<0.05). DAD was far more prevalent than DWI or DD, increasing from 40.5%_wt in Year 2 to 66.9%_wt in Year 5, and plateauing thereafter. Among marijuana-using participants, likelihood of DD was consistently greater than the likelihood of DWI among Heavy Episodic and Light-to-Moderate drinkers, and it declined significantly during Years 5-8 (p<0.05).

CONCLUSION

Post-college declines in heavy drinking and DWI prevalence were encouraging but did not necessarily translate to reductions in likelihood of engaging in DWI, depending on drinking pattern. College-educated individuals represent an important target for AOD-involved driving prevention.

Cannabis and crash responsibility while driving below the alcohol per se legal limit

There is a growing interest in how extensively the use of marijuana by drivers relates to crash involvement. While cognitive, lab-based studies are consistent in showing that the use of cannabis impairs driving tasks, epidemiological, field-based studies have been inconclusive regarding whether cannabis use causes an increased risk of accidents. There is ample evidence that the presence of cannabis among drivers with a BAC≥0.08g/dL highly increases the likelihood of a motor vehicle crash. Less clear, however, is the contribution of cannabis to crash risk when drivers have consumed very little or no alcohol. This effort addresses this gap in knowledge. We took advantage of a unique database that merged fatal crashes in the California Statewide Integrated Traffic Records System (SWITRS) and the Fatality Analysis Reporting System (FARS), which allows for a precise identification of crash responsibility. To account for recent increase in lab testing, we restricted our sample to cover only the years 1993-2009. A total of 4294 drivers were included in the analyses. Descriptive analyses and logistic regressions were run to model the contribution of alcohol and drugs to the likelihood of being responsible in a fatal crash. We found evidence that compared with drivers negative for alcohol and cannabis, the presence of cannabis elevates crash responsibility in fatal crashes among drivers at zero BACs (OR=1.89) and with 0<BAC<0.05g/dL (OR=3.42), suggesting that emphasis on curbing impaired driving should not be solely focused on heavy-drinking drivers. Data limitations however caution about the generalizability of study findings. Special efforts to understand the effect of cannabis on fatal crashes, in particular in the absence of alcohol, are needed.

Fast, Sensitive, and Quantitative Point-of-Care Platform for the Assessment of Drugs of Abuse in Urine, Serum, and Whole Blood

Drug abuse is a major public health problem in many countries in Europe and North America. Currently available platforms for drug abuse assessment are facing technical challenges of nonquantitation, inaccuracy, low throughput, incompatibility with diverse complex specimens, long assay times, and requirement of instrument and/or expertise for readout. Here, we report an integrated competitive volumetric-bar-chart chip (CV-Chip) to assay multiple drug targets at the point-of-care (POC). To the best of our knowledge, it is the first time that a POC platform has been demonstrated to fully address the above-mentioned limitations. We applied this integrated CV-chip platform to assay multiple drugs in 38 patient urine and serum samples and validated the on-chip results with an LC-MS/MS method, indicating a clinical sensitivity and specificity of 0.94 and 1.00, respectively. We further demonstrated that the combination of an on-chip blood separator with the CV-Chip enabled the platform to directly assay finger-prick whole blood samples, which have always been recognized as an ideal biospecimen for POC detections. In summary, this integrated CV-Chip is able to serve as a sensitive, accurate, fast, portable, readout visible, and minimally invasive platform for drug abuse assessment.

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.

Oral fluid testing for marijuana intoxication: enhancing objectivity for roadside DUI testing

Reducing marijuana-impaired driving is an important part of any strategy to prevent motor vehicle traffic injuries. In Colorado, the first of eight US states and the District of Columbia to legalise marijuana for recreational use, drivers with positive tests for the presence of marijuana accounted for a larger proportion of fatal MVCs after marijuana commercialisation. The use of blood tests to screen for marijuana intoxication, in Colorado and elsewhere in the USA, poses a number of challenges. Many high-income countries use oral fluid drug testing (OF) to provide roadside evidence of marijuana intoxication. A 2009 Belgium policy implementing OF roadside testing increased true positives and decreased false positives of suspected marijuana-related driving under the influence (DUI) arrests. US policy-makers should consider using roadside OF to increase objectivity and reliability for tests used in marijuana-related DUI arrests.

Recognizing and Caring for the Intoxicated Patient in an Outpatient Clinic

Recognizing an intoxication syndrome in patients presenting to an outpatient clinical practice with behavior or mental status change requires initial consideration of a broad differential diagnosis. After a thorough evaluation, management may include treatment of the presenting concern, triage to a higher level of care, and management substance withdrawal. Providers should be aware of the medico-legal aspects of caring for intoxicated patients related to privacy, informed consent, and risk of harm to self and others upon leaving clinic. An essential aspect of care for patients presenting to clinic intoxicated is the follow up assessment and management of substance use disorders.

Unique and interactive effects of impulsivity facets on reckless driving and driving under the influence in a high-risk young adult sample

Risky driving behaviors are disproportionately high among young adults and impulsivity is a robust risk factor. Recent conceptualizations have proposed multidimensional facets of impulsivity comprised of negative urgency, premeditation, perseverance, sensation seeking, and positive urgency (UPPS-P model). Prior studies have found these facets are associated with risky driving behaviors in college student samples, but no prior studies have examined these facets in clinical samples. This study examined the unique and interactive effects of UPPS-P impulsivity facets on past-year risky driving behaviors in a sample of high-risk young adults (ages 18-30 years) with a history of substance use and antisocial behavior and their siblings (n=1,100). Multilevel Poisson regressions indicated that sensation seeking and negative urgency were uniquely and positively associated with both frequency of past-year reckless driving and driving under the influence. Moreover, lack of premeditation was uniquely and positively associated with reckless driving, whereas lack of perseverance was uniquely and positively associated with driving under the influence. Furthermore, lack of premeditation moderated and strengthened the positive association between sensation seeking and driving under the influence. These study findings suggest that assessing multiple facets of trait impulsivity could facilitate targeted prevention efforts among young adults with a history of externalizing psychopathology.

Adverse weather conditions and fatal motor vehicle crashes in the United States, 1994-2012

BACKGROUND

Motor vehicle crashes are a leading cause of injury mortality. Adverse weather and road conditions have the potential to affect the likelihood of motor vehicle fatalities through several pathways. However, there remains a dearth of assessments associating adverse weather conditions to fatal crashes in the United States. We assessed trends in motor vehicle fatalities associated with adverse weather and present spatial variation in fatality rates by state.

METHODS

We analyzed the Fatality Analysis Reporting System (FARS) datasets from 1994 to 2012 produced by the National Highway Traffic Safety Administration (NHTSA) that contains reported weather information for each fatal crash. For each year, we estimated the fatal crashes that were associated with adverse weather conditions. We stratified these fatalities by months to examine seasonal patterns. We calculated state-specific rates using annual vehicle miles traveled data for all fatalities and for those related to adverse weather to examine spatial variations in fatality rates. To investigate the role of adverse weather as an independent risk factor for fatal crashes, we calculated odds ratios for known risk factors (e.g., alcohol and drug use, no restraint use, poor driving records, poor light conditions, highway driving) to be reported along with adverse weather.

RESULTS

Total and adverse weather-related fatalities decreased over 1994-2012. Adverse weather-related fatalities constituted about 16 % of total fatalities on average over the study period. On average, 65 % of adverse weather-related fatalities happened between November and April, with rain/wet conditions more frequently reported than snow/icy conditions. The spatial distribution of fatalities associated with adverse weather by state was different than the distribution of total fatalities. Involvement of alcohol or drugs, no restraint use, and speeding were less likely to co-occur with fatalities during adverse weather conditions.

CONCLUSIONS

While adverse weather is reported for a large number of motor vehicle fatalities for the US, the type of adverse weather and the rate of associated fatality vary geographically. These fatalities may be addressed and potentially prevented by modifying speed limits during inclement weather, improving road surfacing, ice and snow removal, and providing transit alternatives, but the impact of potential interventions requires further research.

Prevalence of driving under the influence of psychoactive substances and road traffic crashes among Brazilian crack-using drivers

BACKGROUND

Substance use disorders are associated with the increased risk of driving under the influence (DUI), but little is known about crack-cocaine and its relationship with road traffic crashes (RTC).

METHOD

A multicenter sample of 765 crack-cocaine users was recruited in six Brazilian capitals in order to estimate the prevalence of DUI and RTC involvement. Legal, psychiatric, and drug-use aspects related with traffic safety were evaluated using the Addiction Severity Index - 6th version (ASI-6) and the Mini International Neuropsychiatric Interview.

RESULTS

Seventy-six (28.3%) current drivers reported accident involvement following crack-cocaine use. Among drivers (n=269), 45.7% and 30.5% reported DUIs in the past 6 months and 30 days, respectively. Drivers reporting DUI's in the past month (n=82) had higher scores in the "psychiatric", "legal", and "family problems" subscales from the ASI-6, and lower scores in the "family social support" subscale in comparison to those without a history of DUIs (n=187). An overall high prevalence of psychiatric comorbidity and substance consumption was observed. Participants with 5+ years of crack-cocaine use were more likely to have been in a RTC (RR=1.52, 95%IC: 1.02-2.75), independently of marijuana use, binge drinking and psychiatric comorbidities.

CONCLUSION

The high prevalence of RTC and DUI involvement among crack-using drivers supports the idea that they are at a high risk group regarding traffic safety. Years of crack consumption seem to be associated with RTC involvement. Also, the presence of psychiatric comorbidities, poly-drug use, and cognitive impairment usually associated with crack addiction could yield additional risk of accidents.

The epidemiologic principles underlying traffic safety study designs

This article describes the epidemiological principles underlying four observational study designs commonly used to assess traffic safety: the case-control, case-crossover, culpability and quasi-induced exposure designs. We focus in particular on the specific challenges for preventing bias using each design. Whereas recruiting controls representative of the source population poses a special challenge in case-control traffic safety studies, case-crossover designs are prone to recall bias, and culpability and quasi-induced exposure studies can be undermined by difficulties assigning crash responsibility. Using causal diagrams and worked examples, we provide a simple way to teach traffic safety designs to epidemiologists and to encourage proper application of epidemiological principles among researchers designing traffic safety studies.

Blood alcohol analysis alone versus comprehensive toxicological analysis - Systematic investigation of missed co-ingested other drugs in suspected alcohol-impaired drivers

Driving under the influence of alcohol and/or drugs (DUID) is a safety issue of increasing public concern. When a police officer has reasonable grounds to classify a driver as impaired, he may arrange for a blood sample to be taken. In many countries, alcohol analysis only is ordered if impairment is suspected to be exclusively due to alcohol while comprehensive toxicological screening will be performed if additional suspicion for other illegal drugs of abuse (DoA) or medicinal drugs is on hand. The aim of the present study was firstly to evaluate whether signs of impairment can be differentiated to be caused by alcohol alone or a combination of alcohol and other driving-impairing drugs and secondly to which extent additional drugs are missed in suspected alcohol-impaired drivers. A total of 293 DUID cases (negative n=41; alcohol positive only, n=131; alcohol+active drug positive, n=121) analyzed in 2015 in the Canton of Zurich were evaluated for their documented impairment symptoms by translating these into a severity score and comparing them applying principle component analysis (PCA). Additional 500 cases suspected for alcohol-impaired driving only were reanalyzed using comprehensive LC-MS/MS screening methods covering about 1500 compounds. Drugs detected were classified for severity of driving impairment using the classification system established in the DRUID study of the European Commission. As partly expected from the pharmacological and toxicological point of view, PCA analysis revealed no differences between signs of impairment caused by alcohol alone and those caused by alcohol plus at least one active drug. Breaking it down to different blood alcohol concentration ranges, only between 0.3 and 0.5g/kg trends could be observed in terms of more severe impairment for combined alcohol and drug intake. In the 500 blood samples retrospectively analyzed in this study, a total of 330 additional drugs could be detected; in some cases up to 9 co-ingested ones. In total, 37% of all cases were positive for additional drugs, thereby 15% of classic DoAs and further 9% of prescription drugs with a severe risk to cause driving impairment based on the DRUID classification system. A decision whether signs of impairment are related to alcohol alone or to the combination of alcohol and other drugs is impossible. Taking into consideration the high rate of missed drugs in DUI cases, police should think about increasing the number of DUID cases in countries were sanctioning differs between alcohol and alcohol plus drug impaired driving.

The effects of cannabis intoxication on motor vehicle collision revisited and revised

AIMS

To determine whether and to what extent acute cannabis intoxication increases motor vehicle crash risk.

DESIGN

Study 1 replicates two published meta-analyses, correcting for methodological shortcomings. Study 2 is an updated meta-analysis using 28 estimates from 21 observational studies. These included studies from three earlier reviews, supplemented by results from a structured search in Web of Science and Google Scholar, and by the personal libraries of the research team. Risk estimates were combined using random-effects models and meta-regression techniques.

SETTING

Study 1 replicates the analysis of Asbridge et al., based on nine studies from five countries, published 1982-2007; and Li et al., based on nine studies from six countries, published 2001-10. Study 2 involves studies from 13 countries published in the period 1982-2015.

PARTICIPANTS

In study 1, total counts extracted totalled 50 877 (27 967 cases, 22 910 controls) for Asbridge et al. and 93 229 (4236 cases and 88 993 controls) for Li et al. Study 2 used confounder-adjusted estimates where available (combined sample size of 222 511) and crude counts from the remainder (17 228 total counts), giving a combined sample count of 239 739.

MEASUREMENTS

Odds ratios (OR) were used from case-control studies and adjusted OR analogues from culpability studies. The impact of the substantial variation in confounder adjustment was explored in subsample analyses.

FINDINGS

Study 1 substantially revises previous risk estimates downwards, with both the originally reported point estimates lying outside the revised confidence interval. Revised estimates were similar to those of study 2, which found cannabis-impaired driving associated with a statistically significant risk increase of low-to-moderate magnitude [random-effects model OR 1.36 (1.15-1.61), meta-regression OR 1.22 (1.1-1.36)]. Subsample analyses found higher OR estimates for case-control studies, low study quality, limited control of confounders, medium-quality use data and not controlling for alcohol intoxication.

CONCLUSIONS

Acute cannabis intoxication is associated with a statistically significant increase in motor vehicle crash risk. The increase is of low to medium magnitude. Remaining selection effects in the studies used may limit causal interpretation of the pooled estimates.

23 years of toxicology testing fatally injured pilots: Implications for aviation and other modes of transportation

Use of over-the-counter, prescription, and illicit drugs is increasing in the United States (US). Many of these drugs are psychoactive and can affect the user's ability to safely operate a vehicle. However, data about drug use by vehicle operators is typically limited to a small proportion of operators and a short list of drugs. For instance, required testing for commercial vehicle operators following most accidents is limited to a urine test for 11 drugs. By comparison, the Federal Aviation Administration (FAA), routinely tests fatally injured pilots' blood and tissues for hundreds of compounds. This study used the results from these tests to assess drug use in aviation.

METHODS

Using matched data from the FAA's Civil Aerospace Medical Institute toxicology database and the National Transportation Safety Board's (NTSB's) aviation accident database, this study examined trends in the prevalence of over-the-counter, prescription, and illicit drugs identified in toxicology tests of fatally injured pilots between 1990 and 2012. Cases that failed to match or where toxicology testing had not been performed were excluded. Pilots identified by the NTSB investigation as being the "flying pilot" at the time of the accident and results from blood or tissues were included. Toxicology results for ethanol and other alcohols were not included. Positive test results were categorized by drug type and potential for causing impairment. Analysis used SPSS Version 19.1 to perform linear by linear chi-squared statistics.

RESULTS

The study included 6677 pilots or 87% of the eligible subjects. The large majority were male (98%) and flying general aviation operations (96%) at the time of their fatal accident. There were increasing trends in pilots' use of all drugs, potentially impairing drugs, drugs used to treat potentially impairing conditions, drugs designated as controlled substances, and illicit drugs. The most common potentially impairing drug pilots had used was diphenhydramine, a sedating antihistamine that is an active ingredient in many over-the-counter allergy formulations, cold medicines, and sleep aids in the US. Although evidence of illicit drug use was found only in a small number of cases, the percentage of pilots testing positive for marijuana use increased during the study period, mostly in the last 10 years.

Restraint use and risky driving behaviors across drug types and drug and alcohol combinations for drivers involved in a fatal motor vehicle collision on U.S. roadways

Background

While driving impaired is a well-recognized risk factor for motor vehicle (MV) crash, recent trends in recreational drug use and abuse may pose increased threats to occupant safety. This study examines mechanisms through which drug and/or alcohol combinations contribute to fatal MV crash.

Methods

The Fatality Analysis Reporting System (FARS) for 2008–2013 was used to examine drugs, alcohol, driver restraint use, driver violations/errors and other behaviors of drivers of passenger vehicles who were tested for both alcohol and drugs (n = 79,932). Statistical analysis was based on Chi-square tests and multivariable logistic regression. Associations of restraint use and other outcomes with alcohol and drug use were measured by estimated odds ratios (ORs) and 95 % confidence intervals (95 % CIs).

Results

More than half (54.8 %) of the study population were positive for drugs or alcohol at the time of crash. Approximately half of drivers were belted, but this varied from 67.1 % (unimpaired) to 33.0 % (drugs plus alcohol). Compared to the unimpaired, the odds of a driver being unbelted varied: alcohol and cannabis (OR 3.70, 95 % CI 3.44–3.97), alcohol only (3.50,3.36–3.65), stimulants (2.13,1.91–2.38), depressants (2.09,1.89–2.31), narcotics (1.84,1.67–2.02) and cannabis only (1.55,1.43–1.67). Compared to belted drivers, unbelted drivers were over 4 times more likely to die. Driving violations varied across drug/drug alcohol combinations. Speed-related violations were higher for drivers positive for stimulants, alcohol, cannabis, and cannabis plus alcohol, with a more than two fold increase for alcohol and cannabis (2.36, 2.05, 2.71).

Conclusions

Mechanisms through which drugs, alcohol and substance combinations produce increased risks to occupant safety include lowered restraint use and increases in risky driving behaviors, including speeding, lane, passing, turning and signal/sign violations.

Behavioral and Neurophysiological Signatures of Benzodiazepine-Related Driving Impairments

Impaired driving due to drug use is a growing problem worldwide; estimates show that 18-23.5% of fatal accidents, and up to 34% of injury accidents may be caused by drivers under the influence of drugs (Drummer et al., 2003; Walsh et al., 2004; NHTSA, 2010). Furthermore, at any given time, up to 16% of drivers may be using drugs that can impair one's driving abilities (NHTSA, 2009). Currently, drug recognition experts (DREs; law enforcement officers with specialized training to identify drugged driving), have the most difficult time with identifying drivers potentially impaired on central nervous system (CNS) depressants (Smith et al., 2002). The fact that the use of benzodiazepines, a type of CNS depressant, is also associated with the greatest likelihood of causing accidents (Dassanayake et al., 2011), further emphasizes the need to improve research tools in this area which can facilitate the refinement of, or additions to, current assessments of impaired driving. Our laboratories collaborated to evaluate both the behavioral and neurophysiological effects of a benzodiazepine, alprazolam, in a driving simulation (miniSim(TM)). This drive was combined with a neurocognitive assessment utilizing time synched neurophysiology (electroencephalography, ECG). While the behavioral effects of benzodiazepines are well characterized (Rapoport et al., 2009), we hypothesized that, with the addition of real-time neurophysiology and the utilization of simulation and neurocognitive assessment, we could find objective assessments of drug impairment that could improve the detection capabilities of DREs. Our analyses revealed that (1) specific driving conditions were significantly more difficult for benzodiazepine impaired drivers and (2) the neurocognitive tasks' metrics were able to classify "impaired" vs. "unimpaired" with up to 80% accuracy based on lane position deviation and lane departures. While this work requires replication in larger studies, our results not only identified criteria that could potentially improve the identification of benzodiazepine intoxication by DREs, but also demonstrated the promise for future studies using this approach to improve upon current, real-world assessments of impaired driving.

The use of psychoactive prescription drugs among DUI suspects

BACKGROUND

The study seeks to increase understanding of the use of psychoactive prescription drugs among persons suspected of driving under the influence (DUI). We studied whether the use of prescribed psychoactive medication was associated with DUI, and examined the difference in the use of prescription drugs between DUI recidivists and those arrested only once.

METHODS

In this register-based study, persons suspected of DUI (n=29470) were drawn from the Register of DUI suspects, and an age- and gender-matched reference population (n=30043) was drawn from the Finnish general population. Data on prescription drug use was obtained by linkage to the National Prescription Register. The associations of DUI arrest and use of psychoactive prescription drugs in different DUI groups (findings for alcohol only, prescription drugs, prescription drugs and alcohol, illicit drugs) were estimated by using mixed-effect logistic regression.

RESULTS

The use of psychoactive prescription drugs and DUI appeared to be strongly associated, with DUI suspects significantly more likely to use psychoactive prescription drugs compared to the reference population. Gender differences existed, with the use of benzodiazepines being more common among female DUI suspects. Moreover, DUI recidivists were more likely to use psychoactive prescription drugs compared to those arrested only once.

CONCLUSIONS

In addition to alcohol and/or illicit drug use, a significant proportion of DUI suspects were using psychoactive prescription drugs. When prescribing psychoactive medication, especially benzodiazepines, physicians are challenged to screen for possible substance use problems and also to monitor for patients' alcohol or illicit drug use while being medicated.

Prediction of vehicle crashes by drivers' characteristics and past traffic violations in Korea using a zero-inflated negative binomial model

AIMS

Traffic safety is a significant public health challenge, and vehicle crashes account for the majority of injuries. This study aims to identify whether drivers' characteristics and past traffic violations may predict vehicle crashes in Korea.

METHODS

A total of 500,000 drivers were randomly selected from the 11.6 million driver records of the Ministry of Land, Transport and Maritime Affairs in Korea. Records of traffic crashes were obtained from the archives of the Korea Insurance Development Institute. After matching the past violation history for the period 2004-2005 with the number of crashes in year 2006, a total of 488,139 observations were used for the analysis. Zero-inflated negative binomial model was used to determine the incident risk ratio (IRR) of vehicle crashes by past violations of individual drivers. The included covariates were driver's age, gender, district of residence, vehicle choice, and driving experience.

RESULTS

Drivers violating (1) a hit-and-run or drunk driving regulation at least once and (2) a signal, central line, or speed regulation more than once had a higher risk of a vehicle crash with respective IRRs of 1.06 and 1.15. Furthermore, female gender, a younger age, fewer years of driving experience, and middle-sized vehicles were all significantly associated with a higher likelihood of vehicle crashes.

CONCLUSIONS

Drivers' demographic characteristics and past traffic violations could predict vehicle crashes in Korea. Greater resources should be assigned to the provision of traffic safety education programs for the high-risk driver groups.

Emergency department visits vs. fatalities among substance-impaired underage youths involved in motor vehicle crashes

INTRODUCTION

Emergency department (ED) visits resulting from motor vehicle crashes (MVCs) among individuals younger than 21 impaired by alcohol and/or drugs have been less studied than MVC fatalities.

METHOD

Using data from 2004 to 2011, we compare the magnitude and pattern of national ED visit and mortality data for alcohol- and drug-impaired youths involved in MVCs.

RESULTS

Temporal patterns of ED visits are similar to those of fatalities, but the two differ in magnitude. The ratio of ED visits to fatalities is 3.5:1; alcohol related events involvement dominates other drugs in both categories.

DISCUSSION

The volume of injuries serious enough to warrant ED visits imposes significant health, social, and financial burdens. In ED visits, alcohol is the prime source of MVC morbidity burden; other drugs consistently contribute less.

PRACTICAL APPLICATIONS

These incidents are persistent and require interventions aimed at multiple levels of prevention, including stricter corrective steps earlier in the impaired driving career to reduce subsequent incidents. ED visits for MVC injuries can be important "teachable moments." Limitations of the study indicate the need for improved surveillance of underage substance-involved crashes.

The impact of marijuana decriminalization on California drivers

BACKGROUND

The liberalization of marijuana laws has led to concerns that such changes will increase "drugged driving" and crash-related mortality. California decriminalized marijuana effective January 1, 2011; we examine the impact of this change on marijuana-involved driving.

METHODS

We used laboratory testing from roadside surveys and the Fatality Analysis Reporting System (FARS) to assess impacts on weekend nighttime drivers and fatally injured drivers, respectively. We calculated marijuana prevalence (measured by laboratory-confirmed delta-9-tetrahydrocannabinol [THC] in roadside surveys and cannabinoids in FARS) and compared corresponding 95% confidence intervals (CI) to identify statistically significant changes post-decriminalization. We also conducted multiple logistic regression analyses to determine whether the odds of marijuana-involved driving increased significantly after controlling for potential confounders.

RESULTS

There was no statistically significant change in the prevalence of THC-positive driving among weekend nighttime drivers (n=894) in 2012 (9.2%; 95% CI: 6.3, 12.2) compared to 2010 (11.3%; 95% CI: 8.5, 14.0) or in the adjusted odds of testing positive for THC (adjusted odds ratio [AOR]=0.96; 95% CI: 0.57, 1.60). In contrast, we found a statistically significant increase in the prevalence of cannabinoids among fatally injured drivers in 2012 (17.8%; 95% CI: 14.6, 20.9) compared to the pre-decriminalization period 2008-2010 (11.8%; 95% CI: 10.3, 13.3). The adjusted odds of testing positive for cannabinoids were also significantly higher in 2012 (AOR=1.67; 95% CI: 1.28, 2.18).

CONCLUSIONS

Our study generated discrepant findings regarding the impact of decriminalization on marijuana-involved driving in California. Factors that may have contributed to these findings, particularly methodological factors, are discussed.

Effects of minimum legal drinking age on alcohol and marijuana use: evidence from toxicological testing data for fatally injured drivers aged 16 to 25 years

Background

Alcohol and marijuana are among the most commonly used drugs by adolescents and young adults. The question of whether these two drugs are substitutes or complements has important implications for public policy and prevention strategies, especially as laws regarding the use of marijuana are rapidly changing.

Methods

Data were drawn from fatally injured drivers aged 16 to 25 who died within 1 h of the crash in nine states with high rates of toxicology testing based from 1999 to 2011 on the Fatality Analysis Reporting System (N = 7,191). Drug tests were performed using chromatography and radioimmunoassay techniques based on blood and/or urine specimens. Relative risk regression and Joinpoint permutation analysis were used.

Results

Overall, 50.5% of the drivers studied tested positive for alcohol or marijuana. Univariable relative risk modeling revealed that reaching the minimum legal drinking age was associated with a 14% increased risk of alcohol use (RR = 1.14, 95% CI: 1.02 to 1.28), a 24% decreased risk of marijuana use (RR = 0.76, 95% CI: 0.53 to 1.10), and a 22% increased risk of alcohol plus marijuana use (RR=1.22, 95% CI: 0.90 to 1.66). Joinpoint permutation analysis indicated that the prevalence of alcohol use by age is best described by two slopes, with a change at age 21. There was limited evidence for a change at age 21 for marijuana use.

Conclusions

These results suggest that among adolescents and young adults, increases in alcohol availability after reaching the MLDA have marginal effect on marijuana use.

Establishing legal limits for driving under the influence of marijuana

Marijuana has become the most commonly detected non-alcohol substance among drivers in the United States and Europe. Use of marijuana has been shown to impair driving performance and increase crash risk. Due to the lack of standardization in assessing marijuana-induced impairment and limitations of zero tolerance legislation, more jurisdictions are adopting per se laws by specifying a legal limit of Δ9-tetrahydrocannabinol (THC) at or above which drivers are prosecuted for driving under the influence of marijuana. This review examines major considerations when developing these threshold THC concentrations and specifics of legal THC limits for drivers adopted by different jurisdictions in the United States and other countries.

Drug Use among Iranian Drivers Involved in Fatal Car Accidents

BACKGROUND

Although the problem of substance use among drivers is not limited to certain parts of the world, most epidemiological reports on this topic have been published from industrial world.

AIM

To investigate pattern of drug use among Iranian drivers who were involved in fatal road accidents.

METHODS

This study enrolled 51 Iranian adults who were involved in fatal vehicle accidents and were imprisoned thereafter. Data came from a national survey of drug abuse that was done among Iranian prisoners. The survey collected data at the entry to seven prisons in different regions of the country during a 4-month period in 2008. Self-reported lifetime, last year, and last month drug use was measured. Commercial substance screening tests were applied to detect recent substance use (opioids, cannabinoids, methamphetamines, and benzodiazepines).

RESULTS

The commercial substance screening test showed three distinct patterns of recent illicit drug use: opioids (37.3%), cannabinoids (2.0%), opioids and cannabinoids (13.7%). 29.4% were also positive for benzodiazepines. The substance use screening test detected 23.5% of participants who had used drugs but did not disclose any substance use.

CONCLUSION

Opioids are the most common illicit drugs being used by Iranian drivers who are involved in fatal car accidents. The high rate of substance use prior to fatal car accidents in Iran advocates for the need for drug use control policies and programs as major strategies for injury prevention in Iran. There is also a need for substance screening among all drivers involved in fatal car accidents in Iran, as more than 20% of users may not disclose substance use.

Trends in fatal motor vehicle crashes before and after marijuana commercialization in Colorado

BACKGROUND

Legal medical marijuana has been commercially available on a widespread basis in Colorado since mid-2009; however, there is a dearth of information about the impact of marijuana commercialization on impaired driving. This study examined if the proportions of drivers in a fatal motor vehicle crash who were marijuana-positive and alcohol-impaired, respectively, have changed in Colorado before and after mid-2009 and then compared changes in Colorado with 34 non-medical marijuana states (NMMS).

METHODS

Thirty-six 6-month intervals (1994-2011) from the Fatality Analysis Reporting System were used to examine temporal changes in the proportions of drivers in a fatal motor vehicle crash who were alcohol-impaired (≥0.08 g/dl) and marijuana-positive, respectively. The pre-commercial marijuana time period in Colorado was defined as 1994-June 2009 while July 2009-2011 represented the post-commercialization period.

RESULTS

In Colorado, since mid-2009 when medical marijuana became commercially available and prevalent, the trend became positive in the proportion of drivers in a fatal motor vehicle crash who were marijuana-positive (change in trend, 2.16 (0.45), p<0.0001); in contrast, no significant changes were seen in NMMS. For both Colorado and NMMS, no significant changes were seen in the proportion of drivers in a fatal motor vehicle crash who were alcohol-impaired.

CONCLUSIONS

Prevention efforts and policy changes in Colorado are needed to address this concerning trend in marijuana-positive drivers. In addition, education on the risks of marijuana-positive driving needs to be implemented.

Trends in alcohol and other drugs detected in fatally injured drivers in the United States, 1999-2010

Drugged driving is a safety issue of increasing public concern. Using data from the Fatality Analysis Reporting System for 1999-2010, we assessed trends in alcohol and other drugs detected in drivers who were killed within 1 hour of a motor vehicle crash in 6 US states (California, Hawaii, Illinois, New Hampshire, Rhode Island, and West Virginia) that routinely performed toxicological testing on drivers involved in such crashes. Of the 23,591 drivers studied, 39.7% tested positive for alcohol and 24.8% for other drugs. During the study period, the prevalence of positive results for nonalcohol drugs rose from 16.6% in 1999 to 28.3% in 2010 (Z = -10.19, P < 0.0001), whereas the prevalence of positive results for alcohol remained stable. The most commonly detected nonalcohol drug was cannabinol, the prevalence of which increased from 4.2% in 1999 to 12.2% in 2010 (Z = -13.63, P < 0.0001). The increase in the prevalence of nonalcohol drugs was observed in all age groups and both sexes. These results indicate that nonalcohol drugs, particularly marijuana, are increasingly detected in fatally injured drivers.