Driving After Drug or Alcohol Use Report fnldrft.htm

In the 1996 NHSDA, more than one-quarter (28%) of the 166 million drivers age 16 and older reported that they had driven within two hours of drug and/or alcohol use in the past year. [ As stated earlier, all of the behaviors described in this report occurred in the 12 months prior to the NHSDA interview, unless otherwise noted. The 166 million drivers are those age 16+ who reported driving in the past year and answered the question on whether or not they drove within two hours after substance use. ] This included 23 percent, approximately 38 million drivers, who drove after using alcohol but not drugs; one percent, approximately 1.8 million drivers, who drove after using drugs but not alcohol; and four percent, approximately 7 million drivers, who drove following drug use and following alcohol use.

Figure 2.1Percentage and Number (in thousands) of Drivers Age 16+ who Reported Whether or Not They Drove within Two Hours of Substance Use in the Past Year

[ "Non-impaired " drivers are those respondents age 16 and older who drove a motor vehicle in the 12 months prior to the NHSDA interview, but reported that they did not drive within two hours after using drugs and/or alcohol during that same period.]

More than one-quarter (27%) of all drivers, or approximately 45 million people, drove after alcohol use, with or without drug use. As indicated in Table 2, about one-third of drivers age 21-34, male drivers, and residents of the North Central region of the country reported driving after alcohol use. Six percent of all drivers, or approximately 12 million people, drove after drug use, with or without alcohol.

As shown in Figure 2.1a, four percent of drivers, about 6.3 million people, reported driving after marijuana use. Driving after marijuana use was more common among drivers age 16-20 and male drivers than among older and female drivers (see Table 2). Driving after the use of other drugs (i.e., cocaine, and medical and non-medical use of tranquilizers, sedatives, and stimulants) was much less common. Approximately 1.8 million drivers (about 1% of all drivers) reported driving after cocaine use. Another 1.7 million drivers drove after the medical and non-medical use of tranquilizers, while 1.4 million and 0.7 million drivers reported driving after the medical and non-medical use of stimulants and sedatives respectively. [ On the most recent occasion of driving following tranquilizer use, the vast majority of respondents (84%) reported driving following medical use of the drug. Similarly, nearly three-quarters (71%) of those who drove after sedative use reported that on the most recent occasion it was following medical use of the drug. By contrast, less than half (43%) of those who drove after stimulant use reported that on the most recent occasion it was following medical use of the drug.]

Figure 2.1a: Percentage of Drivers Age 16+ who Drove within Two Hours of Drug Use in the Past Year by Drug Used

Figures 2.2 - 2.14 on the following pages provide estimates of the prevalence of driving within two hours of drug use, with or without alcohol, and driving after alcohol use only for various demographic groups. These estimates represent the likelihood that members of a certain demographic group would engage in these behaviors. The data are taken from Tables 3a-5.

Figure 2.2: Percentage of Drivers Age 16+ within Age Groups who Drove within Two Hours of Substance Use in the Past Year by Substance Used

·Drivers age 16-20 were more likely than drivers age 21 and older to report driving within two hours of drug use, with or without alcohol, while drivers age 21 and older were generally more likely than drivers age 16-20 to report driving after alcohol use only. (See Table 3a)

Figure 2.3Percentage of Male and Female Drivers Age 16+ who Drove within Two Hours of Substance Use in the Past Year by Substance Used

·Males were about twice as likely as females to report driving within two hours of drug use, with or without alcohol, and to report driving after alcohol use only. (See Table 3a)

Figure 2.4Percentage of Drivers Age 16+ within Racial/Ethnic Groups who Drove within Two Hours of Substance Use in the Past Year by Substance Used

·Non-Hispanic whites were more likely than Hispanics to report driving within two hours of drug use, with or without alcohol. Non-Hispanic whites were also more likely than Hispanics, who both were more likely than non-Hispanic blacks, to report driving after alcohol use only. (See Table 3a)

Figure 2.5: Percentage of Drivers Age 16+ within each Region who Drove within Two Hours of Substance Use in the Past Year by Substance Used

·Drivers in the West, but not the South were slightly more likely than those in the Northeast to report driving within two hours of drug use, with or without alcohol. Residents of the North Central region were the most likely to report driving after alcohol use only. (See Table 3a)

Figure 2.6: Percentage of Drivers Age 16+ within Marital Categories who Drove within Two Hours of Substance Use in the Past Year by Substance Used

·Never married drivers were more than three times as likely as married drivers, and twice as likely as divorced, separated, or widowed drivers, to report driving within two hours of drug use, with or without alcohol. Driving after alcohol use only was equally common among married, divorced, separated or widowed and never married drivers. (See Table 3b)

Figure 2.7: Percentage of Drivers Age 16+ within Educational Levels who Drove within Two Hours of Substance Use in the Past Year by Substance Used

·Drivers with only some college education were significantly more likely than college graduates to report driving within two hours of drug use, with or without alcohol. With each increase in educational level, drivers were significantly more likely to report driving after alcohol use only. College graduates were three times as likely as those with less than a high school education to report driving after alcohol use. (See Table 3b)

Figure 2.8: Percentage of Drivers Age 16+ within Employment Categories who Drove within Two Hours of Substance Use in the Past Year by Substance Used

·The unemployed were the most likely to report driving within two hours of drug use, with or without alcohol, and full-time workers were the most likely to report driving after alcohol use only. Those not in the work force were least likely to report either behavior. (See Table 3b)

Figure 2.9: Percentage of Drivers Age 16+ within Personal Income Levels who Drove within Two Hours of Substance Use in the Past Year by Substance Used

·Those with annual personal incomes less than $10,000 were generally more likely than those with higher incomes to report driving within two hours of drug use, with or without alcohol. By contrast, those with higher incomes were more likely than those with lower incomes to report driving after alcohol use only. (See Table 3b)

Figure 2.10: Percentage of Drivers Age 16+ within Gender by Age Groups who Drove within Two Hours of Substance Use in the Past Year by Substance Used

·Regardless of age, males were more likely than females to report driving within two hours of drug use, with or without alcohol, and after alcohol use only. This difference was especially marked for drivers age 21 and older. For drivers age 21 and older, males were twice as likely as females to drive after alcohol use. (See Table 4)

Figure 2.11: Percentage of Drivers Age 16+ within Racial/Ethnic by Age Groups who Drove within Two Hours of Substance Use in the Past Year by Substance Used

·For non-Hispanic whites, driving within two hours of drug use, with or without alcohol, was more common among those age 16-20 than among drivers age 21 and older; whereas, the reverse was true for driving after alcohol use only. The same pattern was found for non-Hispanic black and Hispanic drivers; however, almost all of the estimates for these groups lacked statistical precision. (See Table 4)

Figure 2.12: Percentage of Drivers Age 16+ within Racial/Ethnic by Gender Groups who Drove within Two Hours of Substance Use in the Past Year by Substance Used

·For non-Hispanic whites, males were more likely than females to report driving within two hours of drug use, with or without alcohol, and to report driving after alcohol use only. In fact, this gender difference was found among all racial/ethnic groups for those who reported driving after alcohol use. Regardless of race, males were about twice as likely as females to report driving after alcohol use. (See Table 4)

Figure 2.13: Percentage of Drivers Age 16+ with and without Past-Year Arrests who Drove within Two Hours of Substance Use in the Past Year by Substance Used

·Those who had been arrested in the past year were more likely than those who had not been arrested to report driving within two hours of drug use, with or without alcohol. In fact, those who had been arrested were four times as likely as those who had not been arrested to report driving after drug use. Those who had been arrested were also more likely than those who had not been arrested to report driving after alcohol use only. (See Table 5)

Figure 2.14: Percentage of Drivers Age 16+ on Probation and Not on Probation in the Past Year who Drove within Two Hours of Substance Use in the Past Year by Substance Used

·Those who were on probation in the past year were more likely than those who were not on probation to report driving within two hours of drug use, with or without alcohol. In fact, those who were on probation were four times as likely as those who had not been on probation to report driving after drug use. (See Table 5)

A. Demographic Characteristics

The previous figures provided prevalence estimates for driving within two hours of drug use, with or without alcohol, and driving after alcohol use only. The figures in this section provide demographic profiles of each of these groups of drivers. When appropriate, demographic comparisons between those who drove after drug use and those who drove after alcohol use are made. The data presented in this section are taken from Tables 6-7.

Figure 2.15: Age Distribution of Drivers Age 16+ who Drove within Two Hours of Substance Use in the Past Year by Substance Used

·The majority of those who drove within two hours of drug use, with or without alcohol, and of those who drove after alcohol use only were age 26-49 (57% and 61%, respectively). However, a higher percentage of those who drove after drug use than of those who drove after alcohol use were age 16-20. (See Table 6a)

Figure 2.16: Gender Distribution of Drivers Age 16+ who Drove within Two Hours of Substance Use in the Past Year by Substance Used

·About two-thirds of those who drove within two hours of drug use, with or without alcohol, as well as of those who drove after alcohol use only, were male. (See Table 6a)

Figure 2.17: Racial/Ethnic Distribution of Drivers Age 16+ who Drove within Two Hours of Substance Use in the Past Year by Substance Used

·The vast majority of those who reported driving within two hours of drug use, with or without alcohol, and of those who drove after alcohol use only were non-Hispanic white. However, non-Hispanic blacks were slightly more likely to have driven after drug use than after alcohol use. (See Table 6a)

Figure 2.18: Marital Distribution of Drivers Age 16+ who Drove within Two Hours of Substance Use in the Past Year by Substance Used

·Nearly half of those who drove within two hours of drug use, with or without alcohol, had never been married; whereas, only one-quarter of those who drove after alcohol use only had never been married. By contrast, more than 60 percent of those who drove after alcohol use were married, while slightly more than one-third of those who drove after drug use were married. (See Table 6b)

Figure 2.19: Educational Distribution of Drivers Age 16+ who Drove within Two Hours of Substance Use in the Past Year by Substance Used

·More than half (54%) of those who drove within two hours of drug use, with or without alcohol, had a high school education or less. By contrast, almost two-thirds (64%) of those who drove after alcohol use only had at least some college education. (See Table 6b)

Figure 2.20: Employment Distribution of Drivers Age 16+ who Drove within Two Hours of Substance Use in the Past Year by Substance Used

·The majority of those who drove within two hours of drug use, with or without alcohol, and of those who drove after alcohol use only were employed full-time. However, a higher percentage of those who drove after drug use than of those who drove after alcohol use were unemployed. (See Table 6b)

Figure 2.21: Personal Income Distribution of Drivers Age 16+ who Drove within Two Hours of Substance Use in the Past Year by Substance Used

·More than half of those who drove within two hours of drug use, with or without alcohol, had an annual personal income less than $20,000. In fact, those who drove after drug use were more than twice as likely as those who drove after alcohol use only to have an income of less than $10,000. (See Table 6b)

Figure 2.22: Racial/Ethnic by Gender Distribution of Drivers Age 16+ who Drove within Two Hours of Substance Use in the Past Year by Substance Used

·Regardless of race, the majority of those who drove within two hours of drug use, with or without alcohol, and of those who drove after alcohol use only were male. However, for non-Hispanic blacks, a significantly higher percentage of those who drove after alcohol use than of those who drove after drug use were male. The same was true for Hispanics, but the estimate for driving after drug use lacked statistical precision. (See Table 7)

Figure 2.23: Past-Year Arrest Distribution of Drivers Age 16+ who Drove within Two Hours of Substance Use in the Past Year by Substance Used

·The majority of both those who drove within two hours of drug use, with or without alcohol, and of those who drove after alcohol use only had not been arrested in the past year for any reason. However, those who drove after drug use were more than twice as likely as those who drove after alcohol use, and more than four times as likely as non-impaired drivers [ As stated earlier, "non-impaired " drivers are those respondents age 16 and older who drove a motor vehicle in the 12 months prior to the NHSDA interview, but reported that they did not drive within two hours after using drugs and/or alcohol during that same period.] , to report that they had been arrested during the past year. (See Table 8)

Figure 2.24: Past-Year Probation Status Distribution of Drivers Age 16+ who Drove within Two Hours of Substance Use in the Past Year by Substance Used

·The vast majority of both those who drove within two hours of drug use, with or without alcohol, and those who drove after alcohol use only were not on probation during the past year for any reason. However, both those who drove after alcohol and non-impaired [ As stated earlier, "non-impaired " drivers are those respondents age 16 and older who drove a motor vehicle in the 12 months prior to the NHSDA interview, but reported that they did not drive within two hours after using drugs and/or alcohol during that same period.] drivers were more likely than those who drove after drug use to have not been on probation. (See Table 8)

B. Driving Patterns

This section describes the driving patterns of drivers age 16 and older who reported driving within two hours of marijuana use, with or without alcohol, in the past year. The goal of this section is to summarize the circumstances of the most recent reported occasions of driving following marijuana use. The data presented in this section are taken from Tables 9-11.

Figure 2.25: Distribution of Size of Road Driven on Most Recent Occasion of Driving within Two Hours of Marijuana Use for Drivers Age 16+ who Drove Following Marijuana Use in the Past Year by Age Group

·On the most recent reported occasion of driving within two hours of marijuana use, with or without alcohol, the majority of all driving occurred on smaller roads, for both those age 16-20 and those age 21 and older. (See Table 9)

Figure 2.26: Distribution of Area Driven on Most Recent Occasion of Driving within Two Hours of Marijuana Use for Drivers Age 16+ who Drove Following Marijuana Use in the Past Year by Age Group

·On the most recent reported occasion of driving within two hours of marijuana use, with or without alcohol, the majority of all driving was in urban areas, rather than rural or suburban areas, regardless of the driver’s age. (See Table 9)

Figure 2.27: Distribution of Day of Week Driven on Most Recent Occasion of Driving within Two Hours of Marijuana Use for Drivers Age 16+ who Drove Following Marijuana Use in the Past Year by Age Group

·On the most recent reported occasion of driving within two hours of marijuana use, with or without alcohol, the majority of all driving took place on the weekend, rather than on a weekday, regardless of the driver’s age. (See Table 9)

Figure 2.28: Distribution of Time of Day Driving Began on Most Recent Occasion of Driving within Two Hours of Marijuana Use for Drivers Age 16+ who Drove Following Marijuana Use in the Past Year by Age Group

·On the most recent reported occasion of driving within two hours of marijuana use, with or without alcohol, about half of all driving began between 6:00 p.m. and 11:59 p.m., regardless of the driver’s age. However, a higher percentage of drivers age 16-20 than of drivers age 21 and older began driving between 12:00 a.m. and 5:59 a.m. (See Table 9)

Figure 2.29: Distribution of Starting Point on Most Recent Occasion of Driving within Two Hours of Marijuana Use for Drivers Age 16+ who Drove Following Marijuana Use in the Past Year by Age Group

·On the most recent occasion of driving within two hours of marijuana use, with or without alcohol, the majority of drivers age 16-20 drove from a friend or relative’s home. By contrast, drivers age 21 and older were just as likely to have driven from their own home as from a friend or relative’s home. (See Table 10)

Figure 2.30: Distribution of Destination on Most Recent Occasion Drove within Two Hours of Marijuana Use for Drivers Age 16+ who Drove Following Marijuana Use in the Past Year by Age Group

·On the most recent occasion of driving within two hours of marijuana use, with or without alcohol, about half of all drivers were driving home. However, drivers age 16-20 were more likely than drivers age 21 and older to drive to a friend or relative’s home. (See Table 10)

Figure 2.31: Percentage of Drivers Age 16+ who Drove within Two Hours of Marijuana Use in the Past Year Reporting Reasons for Driving on Most Recent Occasion of Driving Following Marijuana Use by Age Group

·For the most recent occasion of driving within two hours of marijuana use, with or without alcohol, the most common reasons for driving reported by drivers of all ages were "no other way to get there" and "not high enough to cause a crash." (See Table 11)

C. Perceptions of Drivers

This section describes the perceptions of drivers who reported driving within two hours of marijuana use, with or without alcohol, in the past year. The purpose of this section is to document these drivers’ perceptions of their ability to drive safely and their likelihood of being stopped by the police when driving following marijuana use. The data presented in this section are taken from Tables 12 and 13.

Figure 2.32: Distribution of Perceived Extent to which Marijuana Affected Ability to Drive Safely on Most Recent Occasion of Driving within Two Hours of Marijuana Use for Drivers Age 16+ who Drove Following Marijuana Use in the Past Year by Age Group

·Regardless of age, those who reported driving within two hours of using marijuana, with or without alcohol, were about equally likely to feel that on the most recent occasion that they drove after marijuana use, their ability to drive safely was affected "a little" or "a lot" or not at all. (See Table 12)

Figure 2.33: Distribution of Perceived Likelihood of Being Stopped by the Police when Driving Following Marijuana Use Compared to when Driving on Other Occasions for Drivers Age 16+ who Drove within Two Hours of Marijuana Use in the Past Year by Age Group

·The majority of drivers age 16 and older who reported driving within two hours of marijuana use, with or without alcohol, felt that they were "no more likely" to be stopped by the police if driving after using marijuana than when driving on other occasions. However, drivers age 21 and older were more likely than drivers age 16-20 to hold this belief. (See Table 13)

D. Substance Use Patterns

This section primarily describes the substance use patterns of drivers age 16 and older who reported driving within two hours of marijuana use, with or without alcohol. Where possible, comparisons are made to the substance use patterns of those who reported driving after alcohol use only. The goal of this section is to estimate the frequency of substance use and the multi-drug use patterns of drivers who reported driving following drug use. The data presented in this section are taken from Tables 14-17.

Figure 2.34: Distribution of Number of Days in Past Month Drove within Two Hours of Marijuana or Alcohol Use for Drivers Age 16+ who Drove Following Marijuana Use or Alcohol Use in the Past Year by Age Group

·Regardless of age, about 7 out of 10 drivers who reported driving within two hours of marijuana use, with or without alcohol, reported driving following marijuana use on one or more days in the past month. Regardless of age, about 6 out of 10 drivers who reported driving after alcohol use only did so on one or more days in the past month. However, drivers age 21 and older were more likely than drivers age 16-20 to report driving after alcohol use between one and five days in the past month. (See Table 14)

Figure 2.35: Distribution of Level of Past-Year Marijuana Use for Drivers Age 16+ who Drove within Two Hours of Marijuana Use or Alcohol Use Only in the Past Year by Age Group [ Low marijuana use is defined as past-year use, but not weekly or monthly use. Medium marijuana use is defined as monthly, but not weekly use. Heavy marijuana use is defined as weekly marijuana use.] and Past-Month Alcohol Use [ Low alcohol use is defined as having at least one drink, but never more than four on any single occasion in the past 30 days. Medium alcohol use is defined as having at least five drinks on at least one, but fewer than five, occasions in the past 30 days (i.e., binge drinking). Heavy alcohol use is defined as having at least five drinks on at least five occasions in the past 30 days. ]

·Regardless of age, about 60 percent of drivers who reported driving within two hours of marijuana use, with or without alcohol, reported heavy/weekly past-year marijuana use. By contrast, the majority of those who reported driving after alcohol use only, reported low or medium alcohol use; however, drivers age 16-20 were twice as likely as drivers age 21 and older to report heavy alcohol use. (See Table 15)

Figure 2.36: Distribution of Whether or Not Other Substances Were Also Used on Most Recent Occasion of Driving within Two Hours of Marijuana Use for Drivers Age 16+ who Drove Following Marijuana Use in the Past Year by Age Group

·Regardless of age, the majority of those who drove within two hours of marijuana use, with or without alcohol, in the past year used only marijuana on the most recent occasion of driving after marijuana use. However, drivers age 16-20 were more likely than drivers age 21 and older to report driving after using only marijuana, while drivers age 21 and older were more likely than drivers age 16-20 to report driving after using marijuana in combination with alcohol. (See Table 16)

Figure 2.37: Percentage of Drivers Age 16+ who Drove within Two Hours of Marijuana Use in the Past Year Reporting Use of Other Substances when Driving Following Marijuana Use by Age Group

·For those who reported driving within two hours of marijuana use, with or without alcohol, drivers age 16-20 were almost twice as likely as drivers age 21 and older to report driving after using marijuana in combination with other drugs such as cocaine, heroin, tranquilizers, analgesics, stimulants, sedatives, and inhalants. (See Table 17)

E. Blood Alcohol Concentration

In previous sections of this chapter, those who drove after drug and/or alcohol use have been characterized without any indication of the level of their impairment while driving. Blood alcohol concentration (BAC) levels are the primary indices of the level of driver impairment following alcohol use; however, there is no comparable measure for impairment following drug use.

In order to address level of impairment, this section uses the amount and timing of alcohol consumption prior to driving, along with the physical characteristics of the driver, to estimate the driver’s BAC level. (The method by which the estimated BAC levels were calculated is described in greater detail in Appendix D.) The goal of this section is to provide estimates of the BAC levels of drivers within age and gender categories. The data presented in this section are taken from Tables 18-20.

Figure 2.38: Distribution of Number of Drinks Consumed on Most Recent Occasion of Driving within Two Hours of Alcohol Use for Drivers Age 16+ who Drove Following Alcohol Use in the Past Year by Age Group

·For those who reported driving within two hours of alcohol use, with or without drugs, those age 16-20 were about three times as likely as drivers age 21 and older to have consumed at least five drinks on the most recent occasion of driving after alcohol use. By contrast, the majority of drivers age 21 and older consumed one or two drinks on the most recent occasion of driving following alcohol use. (See Table 18)

Figure 2.39: Distribution of Number of Hours between First and Last Drink on Most Recent Occasion of Driving within Two Hours of Alcohol Use for Drivers Age 16+ Who Drove Following Alcohol Use in the Past Year by Age Group

·Among those who reported driving within two hours of alcohol use, with or without drugs, nearly twice as many drivers age 16-20 as drivers age 21 and older consumed their first and last drink within an hour on the most recent occasion of driving after alcohol use. (See Table 17.)

Figure 2.40: Distribution of Time between Last Drink and when Driving Began on Most Recent Occasion of Driving within Two Hours of Alcohol Use for Drivers Age 16+ who Drove Following Alcohol Use in the Past Year by Age Group

·Regardless of age, about 60 percent of those who drove within two hours of alcohol use in the past year drove within one hour after they consumed their last drink.

Figure 2.41: Distribution of Estimated Blood Alcohol Concentration Levels on Most Recent Occasion of Driving within Two Hours of Alcohol Use for Drivers Age 16+ who Drove Following Alcohol Use in the Past Year by Gender

·The vast majority of drivers who reported driving within two hours of alcohol use, with or without drugs, had estimated BAC levels less than .08 g/dl on the most recent occasion of driving following alcohol use; however, a greater percentage of females than males had an estimated BAC level of .08 g/dl or higher. (See Table 19)

Figure 2.42: Average Estimated Blood Alcohol Concentration Level on Most Recent Occasion of Driving within Two Hours of Alcohol Use for Male and Female Drivers Age 16+ who Drove Following Alcohol Use in the Past Year by Age

·For the most recent occasion of driving after alcohol use, with or without drugs, drivers age 16-20 had the highest average estimated BAC level (.087 g/dl). Additionally, females age 26 and older generally had slightly higher estimated BAC levels than males of the same age. (See Table 20)

SAMHSA, an agency in the Department of Health and Human Services, is the Federal Government's lead agency for improving the quality and availability of substance abuse prevention, addiction treatment, and mental health services in the United States.

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Chapter 2: DRUG USE AND DRIVING BEHAVIORS

A. Demographic Characteristics

B. Driving Patterns

C. Perceptions of Drivers

D. Substance Use Patterns

E. Blood Alcohol Concentration