2007 National Roadside Survey of Alcohol and Drug Use by Drivers

2007 National Roadside Survey of Alcohol and Drug Use by Drivers: Drug Results“Medications.” Additionally, some respondents tested positive for more than one category ofdrug. Thus, tables presenting drug categories present four mutually exclusive categories: Illegal;Medications; Illegal and Medications; and Negative. So as not to double count individualpositive results, an individual’s result appears in only one of these categories. However, forexample in Table 3, to determine the proportion of daytime drivers who tested positive for illegaldrugs, one could sum the daytime values for the “Illegal” category (5.8%) and for the ” Illegal &Medications” category (0.5%) to arrive at a prevalence estimate of 6.3% of daytime drivers whowere positive for at least one illegal drug. Detailed summaries of prevalence estimates forindividual drugs appear in Tables 137-140 later in the report. As indicated in Table 3,comparison of drug categories by time of day revealed that, based on oral fluid analyses, almost6 percent of daytime drivers tested positive for drugs in the “Illegal” category (primarilymarijuana and cocaine), as opposed to over 10 percent of nighttime drivers. There was astatistically significant difference between daytime and nighttime drivers (p < .01).Table 3. Drug Categories Distribution by Time of Day (Oral Fluid)Time of Day Drug CategoryN(Unweighted)%(Weighted)Illegal 125 5.8%Medications 107 4.8%DaytimeIllegal & Medications 14 0.5%Negative 1,604 89.0%Overall Daytime 1,850 100.0%Illegal 575 10.5%Medications 201 3.0%NighttimeIllegal & Medications 60 0.9%Negative 5,033 85.6%Overall Nighttime 5,869 100.0%“Medications” includes prescription and over-the-counter drugs.Positive results in the “Medications” category, though not statistically significant, were found tobe slightly higher among the daytime drivers (almost 5%) than nighttime drivers (3%).Additionally, some drivers tested positive for both “Illegal drugs and Medications” (0.5% ofdaytime drivers and 0.9% of nighttime drivers). This indicates that drugs were not detected in89.0 percent of daytime drivers and 85.6 percent of nighttime drivers.When oral fluid drug category findings were combined with BAC results we found that, in boththe daytime and nighttime samples, the drug-positive drivers who were also alcohol-positivewere more likely to be positive for “Illegal” drugs than “Medications” (Table 4). This wasparticularly true in the nighttime sample, in which 17.3 percent of drivers in the illegal categoryhad BACs between zero and .08 grams per deciliter (g/dL) (compared to 6.3% in the“Medications” category) and 5.7 percent had BACs greater than .08 (compared to 1.2% in the“Medications” category) (p < .01). In the daytime sample, however, the differences werestatistically non-significant (p value = .05).4