2007 National Roadside Survey of Alcohol and Drug Use by Drivers

2007 National Roadside Survey of Alcohol and Drug Use by Drivers: Drug ResultsDiscussionThis report summarizes the results of the first U.S. National Roadside Survey to estimate druginvolveddriving prevalence based on biological measures. It should be emphasized that this is aprevalence study, and not a study that addresses the risk that may be presented by drug useamong drivers. For many drug types, drug presence can be detected long after any impairmentthat might affect driving has passed. However, it is important to our understanding of drugs anddriving to know the extent of the use of certain drugs in the driving population. That was theintent of this study.As indicated earlier in the report, we gathered data from drivers on U.S. roadways during Fridaydaytime hours, as well as during Friday nights and Saturday nights. We obtained oral fluidsamples (1,850 during daytime and 5,869 during nighttime) from drivers in each of those datacollection periods, and collected blood samples (3,276), as well, during the nighttime datacollection periods (Table 10).In this study, analyses of the oral fluid and blood samples were conducted to identify thepresence of some 75 drugs and metabolites (Tables 17 and 18). To make the presentation ofresults most useful, we identified six classes of these drugs, including antidepressants, marijuana,narcotic-analgesics, sedatives, stimulants, and other, plus a “more than one drug” class. We alsoidentified three broader categories: illegal, prescription, and over-the-counter. Because few overthe-counterdrugs were found, the prescription and over-the-counter drugs were combined formany analyses and labeled “Medications.”Oral Fluid AnalysesAnalyses of the oral fluid samples obtained from daytime drivers indicated an overall drug useprevalence of 11 percent, and for nighttime drivers, 14.4 percent (Table 19). This includesillegal, prescription, and over-the-counter drugs combined. This overall difference between dayand night is statistically significant (p < .01).In examining the prevalence of drugs by class (Table 31), marijuana was identified in 3.9 percentof daytime drivers and 6.1 percent of nighttime drivers. Sedatives were found in 1.6 percent ofdaytime drivers and in 0.6 percent of nighttime drivers. Conversely, stimulants were found in 1.6percent of daytime drivers but in 3.2 percent of nighttime drivers.Comparison of drug classes by time of day indicated that nighttime drivers were significantlymore likely to test positive for more than one drug class than daytime drivers (2.3% nighttime vs.1.5% daytime) (p < .01). Comparison of drug categories by time of day (Table 34) revealed thatalmost 6 percent of daytime drivers tested positive for drugs in the “Illegal” category (primarilymarijuana and cocaine) as did over 10 percent of nighttime drivers (there was a statisticallysignificant difference between the two groups [p < .01]). Positive results in the “Medications”category (prescription and over-the-counter drugs combined) were found to be slightly higheramong the daytime drivers (almost 5%) than nighttime drivers (3%), although this difference wasnot statistically significant.When examining drug prevalence by time of day and gender (Table 22), the daytime drivingsample showed no statistically significant difference in drug prevalence between males and111