Alcohol- and drug-involved driving in the United States: methodology for the 2007 National Roadside Survey

Exploring substance use and impaired driving among adults aged 21 years and older in the United States, 2015

INTRODUCTION

Alcohol- or drug-impaired driving can cause motor vehicle crashes, injuries, and death. Estimates of drug-impaired driving are difficult to obtain. This study explores self-reported prevalence of and factors associated with alcohol, marijuana, and prescription opioid use and impaired driving among adults aged 21 years and older in the United States.

METHODS

Self-reported data from 3,383 adults in the 2015 Fall ConsumerStyles survey were analyzed. Respondents were asked about alcohol, marijuana, and prescription opioid use and driving while impaired in the last 30 days. Weighted prevalence estimates were calculated. Prevalence ratios and Poisson log-linear regressions were used to identify factors associated with substance use and impaired driving.

RESULTS

Alcohol use was reported by 49.5% (n = 1,676) of respondents; of these, 4.9% (n = 82) reported alcohol-impaired driving. Marijuana use was reported by 5.5% (n = 187) of respondents; of these, 31.6% (n = 59) reported marijuana-impaired driving. Prescription opioid use was reported by 8.8% (n = 298) of respondents; of these, 3.4% (n = 10) reported prescription opioid-impaired driving. Polysubstance use of alcohol and marijuana (concurrent use) was reported by 2.7% (n = 93) of respondents. Among those, 10.8% (n = 10) reported driving impaired by both alcohol and marijuana.

CONCLUSIONS

Impaired driving was self-reported among alcohol, marijuana, and prescription opioid users. This article demonstrates the need for more robust alcohol- and drug-related data collection, reporting, and analyses, as well as the emerging need for surveillance of marijuana and prescription opioid-impaired driving. States can consider using proven strategies to prevent impaired driving and evaluate promising practices.

Prevalence of drug use among drivers based on mandatory, random tests in a roadside survey

Background

In the context of road safety, this study aims to examine the prevalence of drug use in a random sample of drivers.

Methods

A stratified probabilistic sample was designed to represent vehicles circulating on non-urban roads. Random drug tests were performed during autumn 2014 on 521 drivers in Catalonia (Spain). Participation was mandatory. The prevalence of drug driving for cannabis, methamphetamines, amphetamines, cocaine, opiates and benzodiazepines was assessed.

Results

The overall prevalence of drug use is 16.4% (95% CI: 13.9; 18.9) and affects primarily younger male drivers. Drug use is similarly prevalent during weekdays and on weekends, but increases with the number of occupants. The likelihood of being positive for methamphetamines is significantly higher for drivers of vans and lorries.

Conclusions

Different patterns of use are detected depending on the drug considered. Preventive drug tests should not only be conducted on weekends and at night-time, and need to be reinforced for drivers of commercial vehicles. Active educational campaigns should focus on the youngest age-group of male drivers.

Intercorrelation of Alcohol and Other Drug Use Disorders among a National Sample of Drivers

This study examined the relationship between alcohol, marijuana, cocaine, and painkiller use disorders in a sample of drivers. We studied nighttime drivers aged 16 to 87 (n = 4,277) from the 2007 National Roadside Survey who reported substance use behaviors and provided breath tests for alcohol. Logistic regression analyses assessed the relationships between (1) substance (i.e., alcohol/marijuana/cocaine/pain killer) use disorders; (2) demographic characteristics; and (3) BAC levels. Overall, 13.2% of participants met criteria for marijuana use disorder, 7% met criteria for cocaine use disorder, and 15.4% met criteria for extra-medicinal painkiller use disorder. When self-report data were analyzed, three reciprocal associations emerged: (1) marijuana use disorders and alcohol use disorders were correlated; (2) marijuana use disorders and cocaine use disorders were correlated; and (3) cocaine use disorders and painkiller use disorders were correlated. BAC data revealed that marijuana and cocaine use disorders were both associated with positive BAC levels, but only cocaine use disorders were associated with BAC levels over the legal limit. Results suggest significant poly-substance use disorders in a sample of nighttime drivers, with variations by demographic characteristics. The individual and public health consequences of multiple substance use disorders among drivers are significant.

Drinking and driving and perceptions of arrest risk among California drivers: Relationships with DUI arrests in their city of residence

OBJECTIVE

Addressing drinking and driving remains a challenge in the United States. The present study aims to provide feedback on driving under the influence (DUI) in California by assessing whether drinking and driving behavior is associated with the DUI arrest rates in the city in which the driver lives; whether this is due to perceptions that one can get arrested for this behavior; and whether this differed by those drivers who would be most affected by deterrence efforts (those most likely to drink outside the home).

METHODS

This study consisted of a 2012 roadside survey of 1,147 weekend nighttime drivers in California. City DUI arrest rates for 2009-2011 were used as an indicator of local enforcement efforts. Population average logistic modeling was conducted modeling the odds of perceived high arrest likelihood for DUI and drinking and driving behavior within the past year.

RESULTS

As the DUI arrest rates for the city in which the driver lives increased, perceived high risk of DUI arrest increased. There was no significant relationship between either city DUI arrest rates or perceived high risk of DUI arrest with self-reported drinking and driving behavior in the full sample. Among a much smaller sample of those most likely to drink outside the home, self-reported drinking and driving behavior was negatively associated with DUI arrests rates in their city of residence but this was not mediated by perceptions.

CONCLUSION

The results of the present study suggest that perceptions are correlated with one aspect of DUI efforts in one's community. Those who were more likely to drink outside the home could be behaviorally influenced by these efforts.

Alcohol-Impaired Driving: The Influence of Adverse Rearing Environments, Alcohol, Cannabis Use, and the Moderating Role of Anxiety

BACKGROUND

The rate of alcohol-impaired driving (AID) increases during the college years and students who have reported adverse rearing environments appear to be at increased risk for the development of alcohol and drug use behaviors. Alcohol and cannabis are the most commonly used drugs by college students, and these substances are particularly predictive of substance-impaired driving.

OBJECTIVES

The present study aimed to investigate whether adverse rearing environment experiences and level of alcohol and cannabis use are related to the frequency of alcohol-impaired driving and whether anxiety might buffer or accelerate this effect.

METHODS

Data regarding adversity, drug use, anxiety, and AID were obtained from 1,265 students annually, from first to final year of college, over four waves (Mean Age at wave 1 = 18.5 years).

RESULTS

Structural equation modeling supported associations among childhood adversity, alcohol, cannabis, and anxiety symptoms. A significant mediation effect was found such that adversity was predictive of AID via alcohol use and cannabis use. Among men, anxiety symptoms accelerated the path from increased cannabis use and decelerated the path from increased alcohol use to AID frequency. Conclusions/Importance: Childhood adversity is a developmental risk precursor to drug use and AID, whereas anxiety might serve a risk or protective factor to AID, contingent on the drug used.

Acceptance of drinking and driving and alcohol-involved driving crashes in California

BACKGROUND

Alcohol-impaired driving accounts for substantial proportion of traffic-related fatalities in the U.S. Risk perceptions for drinking and driving have been associated with various measures of drinking and driving behavior. In an effort to understand how to intervene and to better understand how risk perceptions may be shaped, this study explored whether an objective environmental-level measure (proportion of alcohol-involved driving crashes in one's residential city) were related to individual-level perceptions and behavior.

METHODS

Using data from a 2012 cross-sectional roadside survey of 1147 weekend nighttime drivers in California, individual-level self-reported acceptance of drinking and driving and past-year drinking and driving were merged with traffic crash data using respondent ZIP codes. Population average logistic regression modeling was conducted for the odds of acceptance of drinking and driving and self-reported, past-year drinking and driving.

RESULTS

A non-linear relationship between city-level alcohol-involved traffic crashes and individual-level acceptance of drinking and driving was found. Acceptance of drinking and driving did not mediate the relationship between the proportion of alcohol-involved traffic crashes and self-reported drinking and driving behavior. However, it was directly related to behavior among those most likely to drink outside the home.

DISCUSSION

The present study surveys a particularly relevant population and is one of few drinking and driving studies to evaluate the relationship between an objective environmental-level crash risk measure and individual-level risk perceptions. In communities with both low and high proportions of alcohol-involved traffic crashes there was low acceptance of drinking and driving. This may mean that in communities with low proportions of crashes, citizens have less permissive norms around drinking and driving, whereas in communities with a high proportion of crashes, the incidence of these crashes may serve as an environmental cue which informs drinking and driving perceptions. Perceptual information on traffic safety can be used to identify places where people may be at greater risk for drinking and driving. Community-level traffic fatalities may be a salient cue for tailoring risk communication.

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.

Impact of age at onset of cannabis use on cannabis dependence and driving under the influence in the United States

BACKGROUND AND AIMS

There is growing evidence that driving under the influence of cannabis is associated with a higher risk of motor vehicle crash. Cannabis dependence has been reported to be associated with a three-fold increased risk of motor vehicle crash. The impact of the age at onset of cannabis use on the risk of both cannabis dependence and driving under the influence of cannabis has not been evaluated so far.

METHODS

Data were drawn from the 2001-2002 National Epidemiological Survey on Alcohol and Related Conditions (NESARC), a survey of 43,093 adults aged 18 years and older. We limited our analyses to the sample of participants who reported having ever used cannabis (n=8172), of whom 8068 had a known age at onset of cannabis use.

RESULTS

Of the 8068 participants included, 5.15% reported having driven under the influence of cannabis. Among those, only a minority (14.46%) were diagnosed with cannabis dependence. Compared to those who start using cannabis at age 21 years or after, participants who used cannabis before the age of 14 years were 4 times more likely to have a history of cannabis dependence and 3 times more likely to reported having driven under the influence of cannabis. An inverse relationship between the age at onset of cannabis use and driving under the influence and risk of cannabis dependence was found.

CONCLUSIONS

Starting to smoke cannabis younger than 21 years is associated with both cannabis dependence and driving under the influence of cannabis.

Driving under the influence of alcohol in Cali, Colombia: prevalence and consumption patterns, 2013

This study's goal was to establish the prevalence of driving under the influence of alcohol (DUI) and alcohol consumption patterns among drivers in Cali, Colombia, in 2013. A cross-sectional study based on a roadside survey using a stratified and multi-stage sampling design was developed. Thirty-two sites were chosen randomly for the selection of drivers who were then tested for blood alcohol concentration (BAC) and asked to participate in the survey. The prevalence of DUI was 0.88% (95% confidence intervals [95% CI] 0.26%-1.49%) with a lower prevalence when BAC was increasing. In addition, a higher prevalence was found during non-typical checkpoint hours (1.28, 95% CI -0.001%-0.03%). The overall prevalence is considered high, given the low alcohol consumption and vehicles per capita. Prevention measures are needed to reduce DUI during non-typical checkpoints and ongoing studies are required to monitor the trends and enable the assessment of interventions.

Prevalence of alcohol-impaired drivers based on random breath tests in a roadside survey in Catalonia (Spain)

Sobriety checkpoints are not usually randomly located by traffic authorities. As such, information provided by non-random alcohol tests cannot be used to infer the characteristics of the general driving population. In this paper a case study is presented in which the prevalence of alcohol-impaired driving is estimated for the general population of drivers. A stratified probabilistic sample was designed to represent vehicles circulating in non-urban areas of Catalonia (Spain), a region characterized by its complex transportation network and dense traffic around the metropolis of Barcelona. Random breath alcohol concentration tests were performed during spring 2012 on 7596 drivers. The estimated prevalence of alcohol-impaired drivers was 1.29%, which is roughly a third of the rate obtained in non-random tests. Higher rates were found on weekends (1.90% on Saturdays and 4.29% on Sundays) and especially at night. The rate is higher for men (1.45%) than for women (0.64%) and it shows an increasing pattern with age. In vehicles with two occupants, the proportion of alcohol-impaired drivers is estimated at 2.62%, but when the driver was alone the rate drops to 0.84%, which might reflect the socialization of drinking habits. The results are compared with outcomes in previous surveys, showing a decreasing trend in the prevalence of alcohol-impaired drivers over time.

Characteristics of designated drivers and their passengers from the 2007 National Roadside Survey in the United States

OBJECTIVE

The objectives of this study were to estimate the prevalence of designated driving in the United States, compare these results with those from the 1996 National Roadside Survey, and explore the demographic, drinking, and trip characteristics of both designated drivers and their passengers.

METHODS

The data used were from the 2007 National Roadside Survey, which randomly stopped drivers, administered breath tests for alcohol, and administered a questionnaire to drivers and front seat passengers.

RESULTS

Almost a third (30%) of nighttime drivers reported being designated drivers, with 84 percent of them having a blood alcohol concentration of zero. Drivers who were more likely to be designated drivers were those with a blood alcohol concentration that was over zero but still legal; who were under 35 years of age; who were African American, Hispanic, or Asian; and whose driving trip originated at a bar, tavern, or club. Over a third of passengers of designated drivers reported consuming an alcoholic drink the day of the survey compared to a fifth of passengers of nondesignated drivers. One fifth of passengers of designated drivers who reported drinking consumed 5 or more drinks that day.

CONCLUSIONS

Designated driving is widely used in the United States, with the majority of designated drivers abstaining from drinking alcohol. However, because designated driving separates drinking from driving for passengers in a group traveling together, this may encourage passengers to binge drink, which is associated with many adverse health consequences in addition to those arising from alcohol-impaired driving. Designated driving programs and campaigns, although not proven to be effective when used alone, can complement proven effective interventions to help reduce excessive drinking and alcohol-impaired driving.

Comparing drug detection in oral fluid and blood: data from a national sample of nighttime drivers

OBJECTIVE

The National Roadside Survey is a study undertaken in the United States to determine the prevalence of alcohol and drugs in randomly selected drivers. Following the success of a 2006 pilot study, the 2007 survey incorporated, for the first time, the collection of biological specimens for drug analysis. This article compares the results obtained from blinded analyses of pairs of oral fluid and blood samples obtained from the same subject.

METHODS

During the 2007 survey, more than 7000 nighttime drivers were randomly stopped and surveyed for their self-reported drug use and were requested to donate an oral fluid specimen using the Quantisal (Immunalysis Corporation, Pomona, CA) device and a blood sample. Overall, 5869 oral fluid specimens were collected from nighttime drivers with 3236 corresponding blood samples.

RESULTS

Biological specimens were analyzed for a wide range of drugs. At nighttime, 14.4 percent of the drivers were positive for drugs in oral fluid, with just over half of those having marijuana present (7.6%). Of the 3236 pairs of specimens, 2676 were negative for all drugs, and 326 matched pairs of samples were both positive, out of which 247 (75.8%) were an exact match for all drug classes and 70 (21.5%) were positive for at least one common drug class.

CONCLUSIONS

Oral fluid and blood samples provided very similar information regarding recent drug intake by randomly tested drivers and oral fluid yielded a higher detection rate for one drug (cocaine) than blood. Oral fluid can be considered a reliable alternative to blood as a matrix for drug testing.

Marijuana as a predictor of concurrent substance use among motor vehicle operators

Despite the adverse effects associated with marijuana abuse and dependence, marijuana is becoming more common-place in activities such as driving. Previous literature has discussed the high rates of cocaine, opioid and benzodiazepine use among users of marijuana, but no research has addressed the rates of concurrent use among drivers meeting abuse or dependence criteria. Each of these substances may produce effects detrimental to driving safety which may be compounded by concurrent substance use. This research examines rates of marijuana use, abuse, and dependence among an active sample of drivers (N = 7,734) in the 2007 National Roadside Survey. Mean age of participants was 36.89 years, and the majority were male (60.1%) and identified as White (59.2%). Participants who used marijuana but did not meet diagnostic criteria for abuse (n = 165) or dependence (n = 112) were significantly more likely to test positive for all substances than were those who did not use marijuana. Further, those that met criteria for marijuana abuse or dependence were more likely than those who did not meet criteria to test positive for THC, cocaine, and benzodiazepines and THC, cocaine, and opioids, respectively. The current research has implications for policy development and drugged driving interventions.

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

Drugged driving is a serious safety concern, but its role in motor vehicle crashes has not been adequately studied. Using a case-control design, the authors assessed the association between drug use and fatal crash risk. Cases (n=737) were drivers who were involved in fatal motor vehicle crashes in the continental United States during specific time periods in 2007, and controls (n=7719) were participants of the 2007 National Roadside Survey of Alcohol and Drug Use by Drivers. Overall, 31.9% of the cases and 13.7% of the controls tested positive for at least one non-alcohol drug. The estimated odds ratios of fatal crash involvement associated with specific drug categories were 1.83 [95% confidence interval (CI): 1.39, 2.39] for marijuana, 3.03 (95% CI: 2.00, 4.48) for narcotics, 3.57 (95% CI: 2.63, 4.76) for stimulants, and 4.83 (95% CI: 3.18, 7.21) for depressants. Drivers who tested positive for both alcohol and drugs were at substantially heightened risk relative to those using neither alcohol nor drugs (Odds Ratio=23.24; 95% CI: 17.79, 30.28). These results indicate that drug use is associated with a significantly increased risk of fatal crash involvement, particularly when used in combination with alcohol.

Driving after drug or alcohol use by US high school seniors, 2001-2011

OBJECTIVES

We examined prevalence, trends, and correlates of driving or riding after use of drugs or alcohol among US high school seniors from 2001 to 2011.

METHODS

Data come from Monitoring the Future, an annual survey of nationally representative samples of high school seniors. We used logistic regressions with data from more than 22,000 respondents to examine multivariate associations with demographic and lifestyle factors.

RESULTS

Large numbers of US high school seniors put themselves and others at great risk of harm by driving after using marijuana or other illicit drugs or drinking alcohol or by riding in a vehicle whose driver had used marijuana, other illicit drugs, or alcohol. Driving after drinking has declined in recent years, but driving after use of marijuana has increased. A higher percentage of students reported driving after using marijuana than after having 5 or more alcoholic drinks. Risky driving and riding behaviors differed little between demographic subgroups but considerably according to lifestyle factors.

CONCLUSIONS

Stronger efforts are needed to combat adolescent driving under the influence of illicit drugs.

Drinking drivers and drug use on weekend nights in the United States

BACKGROUND

Studies of drinking drivers in alcohol-related crashes have shown that high breath-alcohol concentrations (BrACs) are associated with illegal drug use. Until the 2007 National Roadside Survey (NRS), the prevalence of drugs among drinking drivers on U.S. roads was unknown. Using NRS data, we explore how many drivers with positive BrACs may also be using drugs and their significance to current drinking-driving enforcement procedures.

METHODS

Based on a stratified, random sample covering the 48 U.S. contiguous states, we conducted surveys on weekend nights from July-November 2007. Of the 8384 eligible motorists contacted, 85.4% provided a breath sample; 70.0%, an oral fluid sample; and 39.1%, a blood sample. We conducted regression analyses on 5912 participants with a breath test and an oral fluid or blood test. The dependent variables of interest were illegal drugs (cocaine, cannabinoids, street drugs, street amphetamines, and opiates) and medicinal drugs (prescription and over-the-counter).

RESULTS

10.5% of nondrinking drivers were using illegal drugs, and 26 to 33% of drivers with illegal BrACs (≥ 0.08 g/dL) were using illegal drugs. Medicinal drug use was more common among nondrinking drivers (4.0%) than among drivers with illegal BrACs (2.4%).

CONCLUSIONS

The significant relationship between an illegal BrAC and the prevalence of an illegal drug suggests as many as 350,000 illegal drug-using drivers are arrested each year for DWI by U.S. alcohol-impaired driving enforcement. These drug-using drivers need to be identified and appropriate sanctions/treatment programs implemented for them in efforts to extend per se laws to unapprehended drug users.

Drug use disorder (DUD) questionnaire: scale development and validation

BACKGROUND

Despite the ample interest in the measurement of substance abuse and dependence, obtaining biological samples from participants as a means to validate a scale is considered time and cost intensive and is, subsequently, largely overlooked.

OBJECTIVES

To report the psychometric properties of the drug use disorder (DUD) questionnaire including oral fluid and blood sample screening indicators measuring the three most commonly used illicit substances--marijuana, cocaine, and extramedicinal painkillers.

SUBJECTS

Participants were a subset (N = 2,702) of the 2007 U.S. National Roadside Survey that was administered to daytime and nighttime weekend drivers in the 48 contiguous states to examine the prevalence of substance use and misuse.

MEASURES

Participants completed demographic and substance use questions as well as the DUD--a 12-item measure assessing substance abuse and dependence. Participants could potentially have completed the DUD three times for each of the three substances. Subscales of abuse and dependence were created using Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition Text Revision [DSM-IV-TR]) criteria of these diagnoses.

RESULTS

The DUD displayed adequate internal consistency on both subscales of substance abuse and dependence (Cronbach's α ranging from .71 to .84 and .83 to .92, respectively). The DUD also demonstrated construct validity in comparison to biological markers of each substance.

CONCLUSIONS

The DUD is a biologically validated instrument that is both easy to utilize and may have valuable implications as a research tool among both clinical and nonclinical populations.

Drinking and driving in the United States: comparing results from the 2007 and 1996 National Roadside Surveys

OBJECTIVES

The objectives of this study were to (a) use data from the 2007 National Roadside Survey (NRS) to determine the characteristics of weekend nighttime drivers with positive blood alcohol concentrations (BACs) on U.S. roads in 2007; (b) determine the relationship of the driving environment and trip characteristics associated with drinking drivers; and (c) compare the findings for the 2007 NRS with those for the 1996 NRS.

METHODS

Like the 1996 NRS, the 2007 NRS used a stratified random national roadside survey sample of the contiguous 48 states and collected nighttime data on Fridays and Saturdays between 10 p.m. and 3 a.m. Officers directed 8384 drivers into off-road parking areas where our research team asked them to participate in the survey.

RESULTS

Of those approached, 7159 (85.4%) provided a breath test. Results revealed that 12 percent of the nighttime drivers had positive BACs, and of those, 2 percent were higher than the 0.08 BAC illegal limit in the United States. Since the 1996 NRS, we found significant reductions in the percentage of BAC-positive drivers across different demographic groups. Age was among the most significant factors associated with a weekend driver having a positive BAC. The probability that a driver would be drinking peaked in the 21- to 25-year-old age group. Male drivers were more likely than female drivers to be drinking, and Asian and Hispanic drivers were less likely than white drivers to be drinking. Drinking drivers were more likely to be driving short distances (5 or fewer miles) late at night (between 1 and 3 a.m.) and to be coming from a bar or restaurant. Finally, 26 percent of the drivers who reported that they would drive less than 5 miles on the night of the survey had positive BACs, compared to only 16 percent who indicated that they would drive between 6 and 20 miles and 10 percent who planned to drive more than 20 miles.

CONCLUSIONS

The 2007 NRS provides another benchmark in the 4-decade record of drinking drivers on American roads and provides a basis for measuring progress in combating driving under the influence during the coming decade.

Alcohol-related risk of driver fatalities: an update using 2007 data

OBJECTIVE

The purpose of this study was to determine whether the relative risk of being involved in an alcohol-related crash has changed over the decade from 1996 to 2007, a period during which there has been little evidence of a reduction in the percentage of all fatal crashes involving alcohol.

METHOD

We compared blood-alcohol information for the 2006 and 2007 crash cases (N = 6,863, 22.8% of them women) drawn from the U.S. Fatality Analysis Reporting System (FARS) with control blood-alcohol data from participants in the 2007 U.S. National Roadside Survey (N = 6,823). Risk estimates were computed and compared with those previously obtained from the 1996 FARS and roadside survey data.

RESULTS

Although the adult relative risk of being involved in a fatal alcohol-related crash apparently did not change from 1996 to 2007, the risk for involvement in an alcohol-related crash for underage women has increased to the point where it has become the same as that for underage men. Further, the risk that sober underage men will become involved in a fatal crash has doubled over the 1996-2007 period.

CONCLUSIONS

Compared with estimates obtained from a decade earlier, young women in this study are at an increased risk of involvement in alcohol-related crashes. Similarly, underage sober drivers in this study are more at risk of involvement in a crash than they were a decade earlier.

Passengers of impaired drivers

INTRODUCTION

The aims of this study are: (a) to estimate the prevalence of passengers riding with alcohol-impaired drivers; (b) to investigate the role of demographic factors (age, gender, race/ethnicity, educational status) and relevant driving conditions (time of the day, trip origin, vehicle ownership) on shaping the likelihood of alcohol-impaired driving; (c) to identify and estimate the prevalence of passengers as alternative drivers (PADs); and (d) to examine the role that vehicle ownership plays in shaping the occurrence of PADs.

METHOD

Data came from a unique convenience sample of passengers obtained from the 2007 National Roadside Survey, a random sample of drivers from the 48 contiguous states.

RESULTS

The prevalence of PADs in the targeted population (mostly weekend night vehicles) was higher with drivers at .00<BAC<.08 (17%-43%) than at BAC≥.08 (6%-29%) drivers. The evidence suggests that targeted policies to encourage PADs to drive might be possible. However, vehicle ownership is a large impediment for PADs to act as designated drivers. We speculate that vehicle ownership may be a main reason for the less-than expected success of the "designated driver" concept.