Driving Under the Influence of Marijuana and Illicit Drugs Among Persons Aged ≥16 Years — United States, 2018

Alejandro Azofeifa, DDS; Bárbara D. Rexach-Guzmán, MPH; Abby N. Hagemeyer, PhD; Rose A. Rudd, MSPH; Erin K. Sauber-Schatz, PhD

Disclosures

Morbidity and Mortality Weekly Report. 2019;68(50):1153-1157. 

In This Article

Abstract and Introduction

Introduction

In the United States, driving while impaired is illegal. Nonetheless, an estimated 10,511 alcohol-impaired driving deaths occurred in 2018.* The contribution of marijuana and other illicit drugs to these and other impaired driving deaths remains unknown. Data from the Substance Abuse and Mental Health Services Administration's National Survey on Drug Use and Health (NSDUH) indicated that in the United States during 2014, 12.4% of all persons aged 16–25 years reported driving under the influence of alcohol, and 3.2% reported driving under the influence of marijuana.[1] The impairing effects of alcohol are well established, but less is known about the effects of illicit substances or other psychoactive drugs (e.g., marijuana, cocaine, methamphetamines, and opioids, including heroin). This report provides the most recent national estimates of self-reported driving under the influence of marijuana and illicit drugs among persons aged ≥16 years, using 2018 public-use data from NSDUH. Prevalences of driving under the influence of marijuana and illicit drugs other than marijuana were assessed for persons aged ≥16 years by age group, sex, and race/ethnicity. During 2018, 12 million (4.7%) U.S. residents reported driving under the influence of marijuana in the past 12 months; 2.3 million (0.9%) reported driving under the influence of illicit drugs other than marijuana. Driving under the influence was more prevalent among males and among persons aged 16–34 years. Effective measures that deter driving under the influence of drugs are limited.[2] Development, evaluation, and further implementation of strategies to prevent alcohol-impaired, drug-impaired, and polysubstance-impaired driving, coupled with standardized testing of impaired drivers and drivers involved in fatal crashes, could advance understanding of drug- and polysubstance-impaired driving and support prevention efforts.

NSDUH annually collects information about the use of illicit drugs, alcohol, and tobacco among the noninstitutionalized U.S. civilian population aged ≥12 years via household face-to-face interviews using a computer-assisted personal interviewing system.§ Respondents aged <16 years were excluded from this analysis because they are typically too young to drive. Unweighted sample sizes for the 2018 survey cycle included 47,570 respondents aged ≥16 years. Driving under the influence of marijuana was defined as an affirmative response to the question "During the past 12 months, have you driven a vehicle while you were under the influence of marijuana?" Driving under the influence of illicit drugs other than marijuana was defined as an affirmative response to one or more of the questions (each asked separately) that asked about each illicit drug: "During the past 12 months, have you driven a vehicle while you were under the influence of (cocaine, hallucinogens, heroin, inhalants, methamphetamine)"? Public-use NSDUH data on driving under the influence of marijuana and illicit drugs other than marijuana were examined by sex, age group, and race/ethnicity. Data were weighted to provide nationally representative estimates. Statistical analyses were performed using SAS (version 9.4; SAS Institute). Prevalence measures and 95% confidence intervals (CIs) were determined for each response category.

During 2018, the overall prevalence of driving under the influence of marijuana (4.7%) exceeded that of driving under the influence of illicit drugs other than marijuana (0.9%) among persons aged ≥16 years (Table). This pattern persisted when the data were stratified by sex, race/ethnicity, and age group. The prevalences of driving under the influence of marijuana and driving under the influence of illicit drugs other than marijuana were higher among males (6.2%, 1.3%, respectively) than among females (3.2%, 0.5%, respectively). The prevalence of driving under the influence of marijuana was highest among non-Hispanic multiracial persons (9.2%). The prevalence of driving under the influence of marijuana ranged from 0.6% among persons aged ≥65 years to 12.4% among persons aged 21–25 years; the second highest prevalence (9.2%) was reported among persons aged 16–20 years (Figure). The highest reported prevalences of driving under the influence of illegal drugs other than marijuana were among persons aged 21–25 years (1.9%) and 26–34 years (1.9%).

Figure.

Percentage of all persons aged ≥16 years* who reported driving a vehicle under the influence of marijuana or illicit drugs other than marijuana†,§,¶ in the past year, by age group** — National Survey on Drug Use and Health, United States, 2018
*Percentages are weighted to represent the 2018 U.S. civilian, noninstitutionalized population.
Illicit drugs other than marijuana in this analysis include cocaine, hallucinogens, heroin, inhalants, and methamphetamines.
§Not mutually exclusive.
Estimated percentage of adults aged ≥65 years who reported driving under the influence of illicit drugs other than marijuana was <0.02% and thus not shown.
**With 95% confidence intervals indicated by error bars.

*https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/812826.
https://www.cdc.gov/motorvehiclesafety/impaired_driving/strategies.html.
§ https://www.samhsa.gov/data/data-we-collect/nsduh-national-survey-drug-use-and-health. Starting in 2016, NSDUH replaced questions regarding driving under the influence of illicit drugs overall with questions about driving under the influence of individual substances, including cocaine, hallucinogens, heroin, inhalants, marijuana, and methamphetamines.

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