Vital Signs: Drinking and Driving Among High School Students Aged ≥16 Years—United States, 1991-2011 FREE

MMWR. 2012;39:796-800.

2 tables, 1 figure, abstract omitted. Available at http://www.cdc.gov/mmwr/PDF/wk/mm6139.pdf.

Motor vehicle crashes are the leading cause of death among teens aged 16-19 years in the United States.¹ In 2010, a total of 2,211 passenger vehicle occupants aged 16-19 years died in crashes on public roadways; 1,280 (58%) were drivers.² Although every state prohibits persons aged <21 years from driving with any measurable amount of blood alcohol, in 2010, one in five drivers aged 16-19 years involved in fatal crashes had a positive (>0.00%) blood alcohol concentration (BAC).² For this report, CDC used data from the 1991-2011 national Youth Risk Behavior Surveys (YRBS) to describe the trend in drinking and driving among students aged ≥16 years, data from the 2011 national YRBS to describe selected subgroup differences, and data from 41 state YRBSs to examine drinking and driving by state.

The national YRBS, a component of CDC's Youth Risk Behavior Surveillance System (YRBSS), used independent, three-stage cluster samples for the 1991-2011 surveys to obtain cross-sectional data representative of public and private school students in grades 9-12 in all 50 states and the District of Columbia.³ Sample sizes ranged from 10,904 to 16,410 students per year. School response rates ranged from 70% to 81%, student response rates ranged from 83% to 90%, and overall response rates* ranged from 60% to 71%. The state YRBSs, another component of the YRBSS conducted by state education and health agencies, used two-stage cluster samples for the 2011 surveys to obtain cross-sectional data representative of public school students in grades 9-12 in 39 states and of public and private school students in grades 9-12 in two states (Ohio and South Dakota). Sample sizes across states ranged from 1,147 to 13,201 students. School response rates ranged from 73% to 100%, student response rates ranged from 64% to 88%, and overall response rates ranged from 60% to 84%.

For each national survey and the 41 state surveys, students completed a voluntary and anonymous, self-administered questionnaire that included identically worded questions about drinking and driving, current alcohol use, and binge drinking. Drinking and driving was defined as having driven a car or other vehicle one or more times during the 30 days before the survey when they had been drinking alcohol. Current alcohol use was defined as having had at least one drink of alcohol on at least 1 day during the 30 days before the survey. Binge drinking was defined as having had five or more drinks of alcohol in a row (i.e., within a couple of hours) on at least 1 day during the 30 days before the survey. Race/ethnicity data are presented for non-Hispanic black, non-Hispanic white, and Hispanic students (who might be of any race); the numbers of students from other racial/ethnic groups were too small for meaningful analyses.

Data were weighted to provide national or state-level estimates, and the statistical software used accounted for the complex sample designs. All analyses were conducted only among students aged ≥16 years, the age at which teens in every jurisdiction except New Jersey and New York City could be licensed.⁴ Temporal changes during 1991-2011 were analyzed using logistic regression analyses, which controlled for sex, race/ethnicity, and grade and simultaneously assessed significant (p<0.05) linear and quadratic time effects.† T-tests were used to test for significant (p<0.05) differences between subgroups.

During 1991-2011, a significant linear decrease occurred in the prevalence of drinking and driving among U.S. high school students aged ≥16 years (22.3% to 10.3%). A significant quadratic trend also was detected, indicating the prevalence of drinking and driving was stable until 1997 and then declined during 1997-2011.

In 2011, the overall prevalence of drinking and driving was 10.3%, representing approximately 950,000 high school students aged 16-19 years in the United States and approximately 2.4 million episodes of drinking and driving during the past 30 days. Male students (11.7%) were significantly more likely than female students (8.8%) to drink and drive. Drinking and driving was significantly more prevalent among white (10.6%) and Hispanic (11.5%) students than black (6.6%) students. Drinking and driving increased significantly by age, from 7.2% among students aged 16 years to 11.5% among students aged 17 years and 14.5% among students aged ≥18 years. Overall, 26.4% of students reported binge drinking. However, among students who reported drinking and driving, 84.6% reported binge drinking. Prevalence of drinking and driving was more than three times higher among those who binge drank compared with those who reported current alcohol use but did not binge drink (32.1% versus 9.7%).

Among the 41 states with available YRBS results in 2011, prevalence of drinking and driving varied threefold, from 4.6% in Utah to 14.5% in North Dakota (median: 10.1%). States in the highest tertile included much of the upper Midwest; the western states of Montana, Wyoming, and New Mexico; South Carolina; and states along the Gulf Coast, except for Florida (Figure). Prevalence of drinking and driving was significantly higher than the national prevalence in six states (Iowa, Louisiana, Montana, North Dakota, Texas, and Wyoming), lower in nine states (Alaska, Indiana, Kentucky, Michigan, New York, North Carolina, Rhode Island, Utah, and Virginia), and not statistically different in the remaining 26 states.

The findings in this report indicate that substantial progress has been made during the past 2 decades to reduce drinking and driving among teens. However, the findings point to the need to further reduce teen access to alcohol and reduce opportunities to drink and drive. In 2011, one in 10 U.S. high school students aged ≥16 years reported drinking and driving during the past 30 days, and 85% of those students also engaged in binge drinking during the past 30 days.

Declines in both alcohol consumption and driving likely have contributed to the reduction in drinking and driving among high school students. YRBS trend data indicate that alcohol use and binge drinking have declined since the late 1990s.⁵ Similar declines in alcohol use and binge drinking have been reported by another national survey of students, Monitoring the Future.§ Additionally, driving among teens, as reported by that survey, declined substantially during 2000-2010; the proportion of high school seniors who did not drive during an average week increased by nearly one-third during that period, from 15% to 22%.¶ Reasons for the decline in driving among teens are not understood fully, but two factors are widely thought to contribute. First, widespread implementation of graduated driver licensing systems has delayed full licensure for teen drivers by extending the learner driver period and initially restricting independent driving under high-risk conditions such as nighttime driving and transporting young passengers.⁶ Second, teens are especially sensitive to increases in gasoline prices and declines in economic conditions, which might have decreased their miles driven since 2007.⁷

Young persons who drive after consuming any amount of alcohol pose an inordinate risk to themselves, their passengers, and other road users. For each 0.02% increase in BAC, the relative risk of a driver aged 16-20 years dying in a crash is estimated to more than double.⁸ Compared with a sober driver of the same age, a driver aged 16-20 years with a BAC of 0.08%-0.099% is estimated to be 32 times as likely to die in a single-vehicle crash and 13 times as likely to be in a crash in which the young driver lives but someone else dies.⁸ These estimates are especially alarming because, unlike most adults, most high school students who drink alcohol usually do so to the point of intoxication.⁹ Crash fatality data confirm that some teens are drinking heavily before driving. In 2010, according to the National Highway Traffic Safety Administration's Fatality Analysis Reporting System, 697 (20%) of the 3,405 drivers aged 16-19 years involved in fatal crashes (defined as a crash in which at least one person involved in the crash died within 30 days) had positive BACs. Among those 697 teen drivers, 568 (81%) had BACs ≥0.08%, the level designated as illegal for adult drivers (National Highway Traffic Safety Administration, unpublished data, 2012).

Policy developments since the 1980s are credited with reducing alcohol-involved fatal crashes among teens.^6,10- 11 By 1988, every state had enacted laws establishing the minimum legal drinking age of 21 years, leading to an estimated median reduction of 17% in alcohol-involved fatal crashes among teen drivers.¹¹ Minimum legal drinking age laws are estimated to produce $3.60 in total benefits (i.e., reductions in medical costs, work loss, and lost quality of life) for each $1.00 spent (i.e., a 3.6 benefit:cost ratio).¹² During 1983–1998, every state enacted laws establishing a lower BAC (≤0.02%) for drivers aged <21 years. These laws, referred to as “zero tolerance” laws, are estimated to have reduced alcohol-involved fatal crashes among inexperienced drivers by 9%-24%,¹¹ resulting in an estimated 25.0 benefit:cost ratio.¹² More recently, states have introduced graduated driver licensing (GDL) systems. First enacted by Florida in 1996, GDL systems have since been adopted in all 50 states and the District of Columbia.⁴ Although GDL does not directly address drinking and driving, it reduces the behavior by restricting nighttime driving and transporting of young passengers during the first months of licensure.^6,13 A recent national study found that GDL nighttime driving restrictions were associated with a 13% reduction in fatal drinking driver crashes among drivers aged 16 or 17 years relative to drivers aged 19 or 20 years, who are not subject to the restriction.⁶ Although every state except Vermont has a nighttime driving restriction, start times vary from 6 p.m. to 1 a.m.⁴ GDL, with a midnight nighttime driving restriction, is estimated to result in an 8.1 benefit:cost ratio.¹²

The findings in this report are subject to at least six limitations. First, YRBS does not measure whether a student has driven during the 30 days before the survey, so it is not possible to assess prevalence of drinking and driving only among students who drive. According to results from the Monitoring the Future survey, 22% of 12th grade students in 2010 did not drive at all “during an average week.” Second, YRBS defines binge drinking for boys and girls as five or more drinks within a couple hours, which differs from the nationally recommended definition.** The prevalence of binge drinking among girls likely would have been higher if it were defined using a four-drink threshold, consistent with national recommendations. Third, although binge drinking and drinking and driving were strongly associated, data were not available to determine whether binge drinking occurred before driving. Fourth, the extent of underreporting or overreporting of behaviors in YRBS cannot be determined, although the survey questions demonstrate good test-retest reliability.¹⁴ Fifth, these data apply only to youths who attend school and, therefore, are not representative of all persons in this age group. Nationwide, in 2009, of persons aged 16-17 years, approximately 4% were not enrolled in a high school program and had not completed high school.¹⁵ Finally, state-level prevalence estimates of drinking and driving were not available for nine states, including four contiguous western states (Washington, Oregon, California, and Nevada).

Effective interventions that reduce drinking and driving among teens include minimum legal drinking age laws, zero tolerance laws, and GDL. Enhanced enforcement of minimum legal drinking age laws using retailer compliance checks has proven effective in reducing retail sales of alcohol to minors.¹⁶ Families could consider using a parent–teen driver agreement¹⁷ to establish and enforce the “rules of the road” for their newly licensed teen, including complying with all state GDL provisions, never drinking and driving, and always wearing a seat belt. Additionally, teen alcohol consumption^9,18 and drinking and driving patterns¹⁸ are correlated with those of adults living in the same state. Effective strategies to reduce alcohol consumption and drinking and driving aimed at the general population, such as those recommended by the Community Preventive Services Task Force, also can reduce both behaviors among teens.^{10- 11,16,19} Multifaceted community-based programs that address the local social, economic, and legal context in which teens access alcohol and drink and drive²⁰ are more likely to succeed than any single approach. Lastly, effective strategies to increase seat belt use, such as primary seat belt laws and enhanced enforcement of seat belt laws, reduce injury severity when crashes occur.²¹

Reported by: Ruth A. Shults, PhD, Div of Unintentional Injury Prevention, National Center for Injury Prevention and Control; Emily O’Malley Olsen, MSPH, Div of Adolescent and School Health, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, CDC. Corresponding contributor: Ruth A. Shults, rshults@cdc.gov, 770-488-4638.

*Overall response rate = (number of participating schools/number of eligible sampled schools) × (number of usable questionnaires/number of eligible students sampled).

†A quadratic trend indicates a significant but nonlinear trend in the data over time; whereas a linear trend is depicted with a straight line, a quadratic trend is depicted with a curve with one bend. Trends that include significant quadratic and linear components demonstrate nonlinear variation in addition to an overall increase or decrease over time.

§Data available at http://monitoringthefuture.org /data/11data.html#2011data-drugs.

¶Data available at http://monitoringthefuture.org /pubs.html#refvols.

**Definition available at http://www.niaaa.nih.gov/alcohol-health/overview-alcohol-consumption/moderate-binge-drinking.

Tonja Lindsey, National Highway Traffic Safety Administration. Rose Rudd, Div of Unintentional Injury Prevention, National Center for Injury Prevention and Control, CDC.

Key Points