Results of the 2013-2014 National Roadside Survey of Alcohol and Drug Use by Drivers

Abstract

Over the last four decades, the National Highway Traffic Safety Administration and/or the Insurance Institute for Highway Safety (IIHS) conducted four national surveys to estimate the prevalence of drinking and driving in the United States (Wolfe, 1974; Lund & Wolfe, 1991; Voas et al, 1998; Compton & Berning, 2009; Lacey et al, 2009). The first National Roadside Survey (NRS) was conducted in 1973, followed by national surveys of drivers in 1986, 1996, 2007, and now 2013-2014. These surveys used a stratified random sample of weekend nighttime drivers in the contiguous 48 States and collected data directly from drivers on the road.The 2007 NRS added procedures to the NRS for the first time to estimate the use by drivers of other potentially impairing drugs. Prior roadside surveys had only collected breath samples to determine breath alcohol concentration (BrAC). Due to developments in analytical toxicology, NHTSA determined it would be feasible in the 2007 and 2013-2014 surveys to determine driver use of a variety of potentially impairing drugs including illegal drugs as well as legal medications.In 2013-2014, the National Highway Traffic Safety Administration conducted the most recent National Roadside Survey of Alcohol and Drug Use by Drivers.1 This voluntary and anonymous study is the second to collect data on drug use, presenting our first opportunity to examine drug use trends on a national scale. The 2013- 2014 NRS was designed to produce national estimates of alcohol and drug use by weekday daytime and weekend nighttime drivers. Thus, the use rates presented below are national prevalence rates calculated from the percentage of drivers using alcohol or drugs and adjusted with an appropriate weighting scheme.Summary of ResultsPrevalence of Alcohol Use by DriversThe NRS surveys reveal a decreasing trend in alcohol use from the first survey in 1973 to the most recent one in 2013- 2014. Figure 1 shows the percentage of weekend nighttime drivers with BrACs across three categories: BrAC of .005 to .049 g/210 L;2 BrACs of .050 to .079; and BrACs of .080 and higher. The surveys found a decline in each BrAC category. Further, there has been a large decrease in the percentage of drivers who were alcohol positive, from 35.9 percent in 1973 to 8.3 percent in 2013-2014. For BrACs of .08 and higher, there was a decrease from 7.5 percent in 1973 to 1.5 percent in 2013-2014, revealing an impressive 80 percent reduction in the percentage of alcohol-impaired drivers on the road on weekend nights. Also of importance is the decrease from 6.1 percent to 1.6 percent from 1973 to 2013-2014 for BrACs of .050 to .079 category.The 2013-2014 survey found large differences by the day of week and the time of day in the likelihood of drivers being alcohol positive or having an illegal BrAC (Table 1). During weekday daytime hours (Friday), only 1.1 percent of drivers were alcohol positive, while at weekend nighttime hours (Friday and Saturday), 8.3 percent of drivers were alcohol positive. During weekday daytime hours there were very few drivers with illegal BrACs (BrAC > .08), just 0.4 percent, while at weekend nighttime hours 1.5 percent drivers had illegal BrACs. Daytime compared to nighttime percentages are statistically significant. Compared with the NRS 2007, the 2013-2014 NRS BrAC prevalence shown in Figure 1 was significantly lower only for the .005 to .049 BrAC category.Prevalence of Drug Use by DriversThe 2013-2014 study examined the use of drugs, focusing on drugs with the potential to impair driving skills, including over-the-counter, prescription, and illegal drugs.Participants were asked to provide an oral fluid and blood sample in addition to a breath sample. The oral fluid and blood samples were tested for the presence of a large number of potentially impairing drugs including cannabinoids, stimulants, sedatives, antidepressants, and narcotic analgesics. Not all drivers provided both an oral fluid and blood sample; some drivers provided just one sample but many provided both. …