Differences in state drug testing and reporting by driver type in U.S. fatal traffic crashes

Blood alcohol concentration as a measure of risk among pedestrian fatalities in the U.S., 2016-2020

OBJECTIVE

In the United States, deaths among pedestrians have increased dramatically since 2009 relative to other vulnerable road users, with substance use described as an important risk factor. This study aimed to explore blood alcohol concentrations (BAC g/dL) among pedestrian fatalities in the United States between 2016 and 2020. Exploring the presence of alcohol among pedestrian cases will support targeted interventions designed to reduce risk.

METHODS

This study utilized pedestrian fatality and alcohol screening data provided by the Fatality Analysis Reporting System (FARS). Logistic models were examined to identify statistical associations (ORs, 95% CI) by age, race, and sex relative to positive BAC exposure (BAC > 0.0 g/dL), mild exposure (BAC > 0.0 < .079 g/dL), moderate to severe alcohol exposure (BAC 0.08-.299 g/dL), and severe exposure (BAC ≥ 0.30 g/dL).

RESULTS

Between 2016 and 2020, 33,375 pedestrian fatalities were reported to FARS with 75.1% of cases retained for analysis (n = 25,077). Fatalities were more likely to be White (69.3%), male (69.9%), and between 25-64 years of age (67.3%). 74.0% of fatalities were tested for alcohol, with 40.9% screening positive. Females, cases ≥ 75 years of age, and those identified as Asians reported the lowest odds of being positive for alcohol exposure.

CONCLUSIONS

Results suggest an ongoing threat to pedestrians due to alcohol consumption and that exposure odds vary by demographic characteristics. Unfortunately, analytical approaches to understanding the roles played by drugs and alcohol among vulnerable road users tend to be marginalized in the literature. Analytical, evidence-based investigations are needed to curtail the risk of pedestrian fatalities in the U.S.

The kids aren't alright: The effects of medical marijuana market size on adolescents

We exploit shocks to US federal enforcement policy to assess how legal medical marijuana market size affects youth marijuana use and consequences for youth traffic-related fatalities. Using hand-collected data on state medical marijuana patient rates to develop a novel measure of market size, we find that legal market growth increases youth marijuana use. Likely mechanisms are lower prices and easier access. Youth die more frequently from alcohol-involved car accidents, suggesting complementarities for youths. The consequences of marijuana legalization for youth are not immediate, but depend on how supply-side regulations affect production and prices.

The Impact of Cannabis Decriminalization and Legalization on Road Safety Outcomes: A Systematic Review

INTRODUCTION

There is substantial debate concerning the impact of cannabis decriminalization and legalization on road safety outcomes.

METHODS

Seven databases were systematically searched: Embase, MEDLINE, and PsycINFO through Ovid as well as Web of Science Core Collection, SafetyLit, Criminal Justice Database (ProQuest), and Transport Research International Documentation (from inception to June 16, 2021). Eligible primary studies examined group-level cannabis decriminalization or legalization and a road safety outcome in any population.

RESULTS

A total of 65 reports of 64 observational studies were eligible, including 39 that applied a quasi-experimental design. Studies examined recreational cannabis legalization (n=50), medical cannabis legalization (n=22), and cannabis decriminalization (n=5). All studies except 1 used data from the U.S. or Canada. Studies found mixed impacts of legalization on attitudes, beliefs, and self-reported driving under the influence. Medical legalization, recreational legalization, and decriminalization were associated with increases in positive cannabis tests among drivers. Few studies examined impacts on alcohol or other drug use, although findings suggested a decrease in positive alcohol tests among drivers associated with medical legalization. Medical legalization was associated with reductions in fatal motor-vehicle collisions, whereas recreational legalization was conversely associated with increases in fatal collisions.

DISCUSSION

Increased cannabis positivity may reflect changes in cannabis use; however, it does not in itself indicate increased impaired driving. Subgroups impacted by medical and recreational legalization, respectively, likely explain opposing findings for fatal collisions. More research is needed concerning cannabis decriminalization; the impacts of decriminalization and legalization on nonfatal injuries, alcohol and other drugs; and the mechanisms by which legalization impacts road safety outcomes.

Social Status and Opioid Drugged Driving

This study examines the effects of social status on opioid drugged driving fatalities in the context of the ongoing opioid mortality crisis. Broad criminological insights are leveraged to understand how position in the age, race, and sex status hierarchies impacts opioid use by drivers. Analysis of data from the Fatality Analysis Reporting System shows that fatally injured drivers who used opioids prior to the crash were more often male, White, non-Hispanic, and older compared to other statuses. Moreover, the social statuses of opioid drugged drivers are dissimilar to those who used opioids in drug overdose deaths. Results suggest that social status-informed and driver-focused initiatives may be particularly effective in reducing opioid use by drivers.

Impacts of alcohol and opioid polysubstance use on road safety: Systematic review

Connections between substance use, impairment, and road safety have been frequently researched. Yet, little is known about how simultaneous use of opioids and alcohol affects road safety outcomes, which is an increasingly critical link within the current landscape of the substance use environment and public health. Lack of this understanding is partly due to testing complications and data limitations. We define polysubstance use here as alcohol and opioids consumed together or within a small-time window such that both are present in the system. This polysubstance use is on the rise and produces greater health risks than when the substances are consumed separately. Given the increasing rate of opioid use, high prevalence of alcohol use, and dangers of polysubstance use, we aim to synthesize literature on the prevalence and impact of this polysubstance on road safety-related outcomes. We performed a systematic review of studies published between 1974 and 2020 that examined opioid and alcohol use exposures and road safety-related outcomes. Out of 644 initial findings, 20 studies were included in this review. Outcomes included motor vehicle crash injuries, deaths, or driver culpability; suspected driving under the influence; and simulated driving performance. Evidence from multiple sources showed a significant rise, approximately 1% to 7%, in the prevalence of opioids among fatally injured drivers in the U.S. from 1995 to 2016. Information published on the simultaneous presence of opioids and alcohol in people involved in crashes was scarce. The limited available findings point toward an overlap where up to 30% of opioid-positive people involved in a crash were also positive for alcohol. Studies also suggest a possibly elevated risk presented by this polysubstance use relative to the substances used alone, though the majority of identified studies did not estimate this association. The synthesized research indicates that alcohol and opioid use is not uncommon and may be increasing among people involved in adverse driving events. More research and better data are needed to improve estimates of association with road traffic-related outcomes, potentially improving substance testing in current surveillance systems or using linked data sets and other novel data sources to improve estimates.

Simultaneous Alcohol/Cannabis Use and Driving Under the Influence in the U.S

INTRODUCTION

Alcohol and cannabis are commonly involved in motor vehicle crashes and fatalities. This study examines whether simultaneous use of alcohol/cannabis is associated with higher odds of reporting driving under the influence of alcohol and cannabis in the U.S.

METHODS

Drivers aged ≥16 years with any past-year alcohol and cannabis use in the 2016-2019 National Survey on Drug Use and Health (N=34,514) reported any past-year driving under the influence of alcohol-only, cannabis-only, both alcohol/cannabis, or not driving under the influence. Survey-weighted associations between simultaneous alcohol/cannabis use and each of the driving under the influence outcomes were computed adjusting for sociodemographics and daily alcohol/cannabis use. Analyses were conducted from November 2020 to September 2021.

RESULTS

In 2016-2019, 42% of drivers with past-year alcohol and cannabis use reported driving under the influence (8% alcohol-only, 20% cannabis-only, 14% alcohol/cannabis). Simultaneous alcohol/cannabis use was associated with 2.88-times higher adjusted odds of driving under the influence of cannabis-only (95% CI=2.59, 3.19) and 3.51-times higher adjusted odds of driving under the influence of both alcohol/cannabis (95% CI=3.05, 4.05), compared to not driving under the influence. Associations with driving under the influence of alcohol-only were unexpectedly in the opposite direction (adjusted conditional odds ratio=0.59, 95% CI=0.45, 0.79).

CONCLUSIONS

Overall, 2 in 5 drivers who used alcohol and cannabis reported driving under the influence of alcohol and/or cannabis. People reporting simultaneous alcohol/cannabis use were more likely to report cannabis-related driving under the influence. Prevention strategies should target individuals reporting simultaneous alcohol/cannabis use to reduce the occurrence of driving under the influence.

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).

Drug presence in driving deaths in Maryland: Comparing trends and prevalence in medical examiner and FARS data

Accurate and reliable information on drug use by road users is essential to inform safety policy development but the reliability of national data has been questioned. There are two primary repositories of drug test information from fatal motor vehicle crashes in Maryland: (1) the Fatality Analysis Reporting System (FARS), which is a national crash database managed by the US Department of Transportation, and (2) the Maryland Medical Examiner (ME). In this study, we compared drug test information for people killed in crashes in Maryland between the FARS system and ME from 2006 - 2018. As ME records are the primary source for the FARS data from Maryland, these two data sets should be closely correlated. We used probabilistic linkage to match FARS and ME cases and compared matched cases by individual drug group. Matching was achieved on 83 % of cases (N = 4803 matched pairs). ME data consistently indicated higher overall incidence and trends in the presence of depressants, narcotics, and stimulants in crash deaths. Sensitivity analysis using both strict and relaxed matching criteria did not change this result. Road safety policy and prevention efforts for crashes involving drugs and alcohol require an accurate understanding of both long-term trends and year-to-year changes in drug prevalence. These findings demonstrate the potential value of using ME data as source of drug test information for crash deaths in the United States.

An examination of relationships between cannabis legalization and fatal motor vehicle and pedestrian-involved crashes

OBJECTIVE

While attention has been given to how legalization of recreational cannabis affects traffic crash rates, there was been limited research on how cannabis affects pedestrians involved in traffic crashes. This study examined the association between cannabis legalization (medical, recreational use, and recreational sales) and fatal motor vehicle crash rates (both pedestrian-involved and total fatal crashes).

METHODS

We used crash data from the Fatality Analysis Reporting System (FARS) to calculate monthly rates of fatal motor vehicle crashes and fatal pedestrian-involved crashes per 100,000 people from 1991 to 2018. Changes in monthly crash rates in three states that had legalized cannabis (Colorado, Washington, and Oregon) were compared to matched control states using segmented regression with autoregressive terms.

RESULTS

We found no significant differences in pedestrian-involved fatal motor vehicle crashes between legalized cannabis states and control states following medical or recreational cannabis legalization. Washington and Oregon saw immediate decreases in all fatal crashes (-4.15 and -6.60) following medical cannabis legalization. Colorado showed an increase in trend for all fatal crashes after recreational cannabis legalization and the beginning of sales (0.15 and 0.18 monthly fatal crashes per 100,000 people).

CONCLUSIONS

Overall findings do not suggest an elevated risk of total or pedestrian-involved fatal motor vehicle crashes associated with cannabis legalization.

The epidemiology of pedestrian fatalities and substance use in Georgia, United States, 2007-2016

Though U.S. motor vehicle crashes as a whole have decreased over the past few years, fatalities among vulnerable road users have increased. Pedestrian deaths rose nationally by 27% between 2007 and 2016 accounting for 16% of all motor vehicle fatalities. This increase continues to burden transportation specialists, public health professionals, and community stakeholders. Potential risk factors include characteristics of the built environment, distractions, and pedestrians' use of alcohol and drugs. Pedestrian deaths in Georgia, United States, increased 40% between 2014 and 2016 while drug overdose deaths have increased by 18% during the same period. Concurrent increases in mortality due to pedestrian fatalities and drug overdoses make Georgia a natural environment in which to describe the proximity of drugs among pedestrian fatalities, a topic largely overlooked by the literature. This study explores the epidemiology of pedestrian fatalities in Georgia over a 10-year period with an emphasis on reported substance use among cases. The study employed 10-year data from the Fatality Analysis Reporting System (FARS) administered by the National Highway Traffic Safety Administration. Descriptive methods were used to explore drug screens by person, place, and time. We also examined trends in total drug screens over the examination period. Between 2007 and 2016, 1781 pedestrian crashes were reported to FARS; the fatality rate for this period was 94.5%. Of these, most were male with Blacks and Whites equally represented. Ages 15-64 accounted for 81.1% of cases with most occurring in the Atlanta Metropolitan area. When adjusted for population, one finds higher rates in more rural areas of the state. Data revealed that testing for the presence of drugs occurred among half of reported cases. Of those testing positive, five drug categories emerged; stimulants (45.8%), cannabinoids (21.5%), narcotics (including opioids) (14.1%), depressants (12.1%), and "Other Drugs" (6.3%). Positive drug screens across all drug classifications increased by 178.1% between 2007 and 2016. These findings suggest the need for state-wide policies designed to promote more consistent screening among pedestrians involved in motor vehicle crashes as well as diligence in understanding the role played by drugs among this population. Additional investigation should be conducted to tease out the presence of category-specific drugs among pedestrians. Understanding the epidemiology of pedestrian fatalities in the state, especially in relation to substance use, serves as a first step toward implementing localized preventive efforts.

Positive drug test trends in fatally-injured drivers in the United States from 2007 to 2017

Background

The last two decades have seen tremendous changes in the U.S. environment surrounding drugs. Driving under the influence of drugs is a growing public health hazard. The present study examined trends in drug involvement in fatally-injured drivers in the U.S.

Methods

Data were drawn from the 2007–2017 Fatality Analysis Reporting System. Cochran–Armitage tests were performed to assess the statistical significance of changes in the yearly prevalence of positive drug tests in fatally-injured drivers over time. In addition, analyses were stratified by sex, race, and age.

Results

The yearly prevalence of positive drug tests in fatally-injured drivers increased significantly from 20.7% in 2007 to 30.7% in 2017, with results showing a higher prevalence among males, those aged 21–44, and Whites. The gap between Blacks and Whites narrowed in 2017. There was a decline in the yearly prevalence in all age groups between 2016 and 2017, although the decrease in the 21–44 age group was much smaller than other age groups. Among drivers who tested positive for drugs, 34.6% had a blood alcohol concentration (BAC) above the threshold of per se evidence for impaired driving, and 63% had a BAC below the threshold.

Conclusions

Our results indicate that the overall yearly prevalence of fatally-injured drivers who tested positive for drugs increased significantly from 2007 to 2017, with similar results found for subgroups. Findings further highlight that drugged driving remains a public health priority, and more action is needed to stem this disturbing trend.

Epidemiology of alcohol and drug screening among pedestrian fatalities in the United States, 2014-2016

Objective: U.S. pedestrian fatalities increased by 25% between 2010 and 2015. Risk factors include distractions, the built environment, urbanization, economic variables, and weather conditions. Of interest is the role of alcohol and drugs in premature death among pedestrians. This study sought to explore the prevalence of substance use screenings among pedestrian fatalities in the United States between 2014 and 2016. Methods: Data were collected from the Fatality Analysis Reporting System provided by the NHTSA. Pedestrian crash variables included demographics as well as information regarding alcohol or drug testing status. Frequency and cross-tabulation tables were constructed to assess the prevalence of screening by person, place, and time. Log-linear analyses were completed to explore age, race, and sex differences. A 3-year examination period was used to control for yearly fluctuations and to incorporate an increasing trend in cases. Results: Pedestrian fatalities accounted for 84% of all deaths among vulnerable road users during the examination period. Those most at risk were white males between the ages of 45 and 64. Over all states, 74.7% of fatalities were tested for alcohol and 67.1% were tested for drugs; further, 66.5% of cases were tested for both alcohol and drugs and 24.8% were tested for neither substance. Cases screened for both alcohol and drugs ranged from 2.9% in North Carolina to 95.7% in Nevada and those testing for neither substance ranged from a high of 68.9% in Indiana to a low of 1.1% in Maryland. Log-linear regression revealed significant differences in alcohol screening by age and race but not by sex. Differences in drug screening were not identified for any demographic variable. Fatalities tested for alcohol were significantly more likely to be tested for drugs; only 8.2% were screened solely for alcohol and 0.05% were screened for drugs alone. Conclusions: Preventive strategies become more important as pedestrian crashes and fatalities increase. Risk reduction in the form of policy change, alterations to the built environment, or interdisciplinary approaches to injury prevention is dependent upon best evidence supported in part by more deliberate and consistent screening.

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.

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.

The effects of medical marijuana laws on cannabis-involved driving

This study uses data from the Fatality Analysis Reporting System and a differences-in-differences model to examine the effect of state medical marijuana laws (MMLs) on cannabis-involved driving among U.S. drivers involved in a fatal crash between 1993-2014. Findings indicate that MMLs in general have a null effect on cannabis-positive driving, as do state laws with specific supply provisions including home cultivation and unlicensed or quasi-legal dispensaries. Only in jurisdictions with state-licensed medical marijuana dispensaries did the odds of marijuana-involved driving increase significantly by 14 percent, translating into an additional 87 to 113 drivers testing positive for marijuana per year. Sensitivity analyses reveal these findings to be generally robust to alternate specifications, although an observed spillover effect consistent with elevated drugged driving enforcement in bordering states weakens a causal interpretation. Still, reasonable policy implications are drawn regarding drugged driving prevention/enforcement and regulations governing dispensary delivery services and business siting decisions.

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.