Drug use and driving behaviors among drivers with and without alcohol-related infractions

Abstract Introduction Brazil is one of the countries with the highest rates of alcohol-related traffic infractions, but little is known about the profile of the drivers who commit them. Identifying the characteristics of impaired drivers is essential for planning preventive actions. Objective To compare drug use and driving behavior profiles of drivers with and without alcohol-related infractions. Methods 178 drivers stopped at routine roadblocks were assessed by traffic agents who conducted standard roadblock procedures (document verification; request of a breathalyzer test [BT]). Drug use and driving behavior data were collected through semi-structured interviews. Subjects were divided into three groups: drivers who refused the BT (RDs, n = 72), drivers who tested positive on the BT (PDs, n = 34), and drivers who had committed other infractions (ODs, n = 72). Results The proportion of alcohol use in the last year was higher among RDs (100%) than in the PD and OD groups (97.1% and 72.2% respectively, p < 0.001). Lifetime prevalence of cannabis and cocaine use for the overall sample was 44.3% and 18.2%, respectively. Fewer individuals in the OD group (31.5%) reported having been stopped at roadblocks in the previous year compared to the PDs (55.9%) and RDs (48.6%, p = 0.03). However, a higher proportion of RDs reported drunk driving in the same period (87.5%; PD 69.7%; OD 26.9%; p < 0.001). Conclusion Essential differences among groups were observed. RDs had a higher proportion of alcohol use and drunk driving in the previous year; drivers who fit into this particular group may be unresponsive or less responsive to social deterrence and enforcement actions.


Introduction
Traffic collisions (TCs) associated with drunk driving are still a cause of concern worldwide, especially in low and middle-income countries (LMIC), where TCs account for a great proportion of the increase in disability-adjusted life years (DALYs). 1 Among the strategies developed to reduce drunk driving, inspection barriers with random breath testing are shown to be a cost-effective approach, reducing alcohol-related TCs by about 20%. 2 According to the 2009 Global Status Report on Road Safety, 49% of countries that were analyzed have specific laws in place that prohibit drinking and driving with a blood alcohol concentration (BAC) equal to or higher than 0.05g/dl, 3 which is considered by the World Health Organization (WHO) as the best practice for traffic enforcement. In Brazil, laws and policies related to drunk driving have changed significantly over the years. Although the first national law concerning alcohol consumption by drivers was established in 1941, it was only in 1997 that a BAC limit of 0.06g/dl was established. 5,6 In 2008, Brazil implemented stricter laws, with a BAC threshold of zero. 7 Enforcement of the zero tolerance policy prioritizes use of roadside breath tests as the standard procedure for detecting drunk driving; however, when breath testing is not available or cannot be performed, traffic agents may also rely on other types of evidence, such as witness accounts and visible signs and symptoms of impairment. 8 In theory, recognition of signs and symptoms of alcohol impairment by traffic agents can be used as the sole evidence for conviction of a traffic crime or offense, but in practice this procedure is almost never used, due to lack of training both by police officers and members of the court. When drivers are asked to perform a breath test during a roadblock, a number of different outcomes are possible, as shown in Table 1. Legal loopholes exist that allow drivers to refuse to take the breath test, claiming the right not to self-incriminate. Drivers who refuse are subject to the same fines and administrative penalties as drivers with a breath alcohol concentration (BrAC) between 0.04 and 0.35 mg/L of breath. [9][10][11] Evidence shows that it is possible to deter alcohol-

Ethical considerations
This study was approved by the Institutional Review Board at the Hospital de Clínicas de Porto Alegre (HCPA/ GPPG N.14-0685, CAAE 39604114.3.0000.5327). All participants provided written consent. Agreeing or refusing to participate in the study did not add/subtract any legal measures or administrative penalties. All screening results and data collected during the interview were used exclusively for study purposes.

Study design and sampling
This was a cross-sectional roadside survey, and data

Procedures
Drivers who met inclusion criteria were invited to participate by a senior investigator. Drivers received a brief explanation of the study and data on apparent age and traffic infraction were collected for all these individuals. If a driver consented to participation, he or she was taken by a trained interviewer to a private place dedicated to data collection. All consenting drivers After participating in the research, drivers were directed to the responsible traffic agent in order to complete the routine roadblock operation.

Statistical analysis
Categorical variables are expressed as absolute and relative frequencies, and proportions and associations were analyzed using the chi-squared test. We investigated the normality of distribution of continuous data using a histogram and the Shapiro-Wilk test.
Continuous variables were expressed as median and interquartile range and were compared using the Kruskal-Wallis test followed by Dunn's post-hoc test.

Sampling
Of the 3,321 drivers stopped at the checkpoints, 309 met the inclusion criteria and 179 (57.9%) agreed to participate in the study. There were no differences in apparent age or sex between study participants and those who refused to participate; however, breathalyzer results were associated with participant agreement, the proportion of zero BrAC (< 0.04mg/L) was higher among those who agreed to participate (30.7% vs. 19 (Table 3). For instance, a lower proportion of drivers with other types of infractions (excluding those related to impaired driving) had a valid driver's license;

Demographic characteristics and driving profile
nonetheless, the type of vehicle and weekly frequency of driving were similar to the other groups (Table 3).

Self-reported drug use and signs and symptoms of intoxication
Out of the total sample, 88.2% and 68.  (Table 4).
The total number of signs and symptoms of intoxication assessed by traffic agents was similar between groups (p = 0.192), with drivers presenting a median of one sign or symptom in total (Table 4).  (Table 5). Over 50% of the overall sample also reported having been the passenger of a driver impaired by alcohol and/or drugs in the last year.  Data expressed as absolute and relative frequencies, n (%), and compared using the chi-squared test, unless otherwise specified. * Adjusted residual > |2|. † The total n for the analysis of use during the last 3 months is the subset of subjects who reported using the drug during their lifetimes. ‡ The total n for the analysis of use during the last 24 hours is the subset of subjects who reported using the drug during the previous 3 months. § (Table 5).

Discussion
In the present study, we compared drug use profiles, behaviors, and beliefs related to impaired driving among drivers with and without alcohol-related infractions stopped at Brazilian roadblocks, focusing on the characteristics of drivers who refused to take the breathalyzer test. We found that those who refused the test had a higher proportion of alcohol use and drunk driving behavior in the previous year, even though most drivers in this group had already been stopped before at roadblocks and believed in the effectiveness of enforcement.
Several studies have reported a high prevalence and severity of PAS use and dependence among drivers with a history of driving under the influence. [20][21][22][23] Current data in Brazil estimate that around 50% of the population aged 18 years or more has used alcohol in the previous year, 24 compared to 88.2% in our sample. This discrepancy was even higher in the RD group, where the proportion of individuals reporting alcohol use was almost two times greater than the national prevalence.
Although we found no difference in drug use between groups, the overall sample reported a higher proportion of cannabis and cocaine use than those reported for the general population in previous reports (2.4% and 2%, respectively). 24 Since all drug use data were selfreported, it is possible that they were underestimated.
One hypothesis for this result relies on the fact that the sample was approached during night roadblocks, as evidence suggest that the prevalence of alcohol and drug positive drivers increase on week nights and weekends. 25 Besides, the prevalence of alcohol and drug use in Rio Grande do Sul is higher than in most of the country's states. However, history of drug use is not the sole risk for DUI; indeed, comprehensive assessment of drug use profiles, cognitive traits, and personality characteristics seems to be the best way to identify citizens who are higher-risk drivers, as well as to assess those who are not responsive to traditional enforcement measures. 20,26 Policies and enforcement strategies against impaired driving vary greatly between countries and are generally drafted based on local needs. In this context, understanding the profile of drivers with a history of drunk or drugged driving is essential to designing specific approaches to this public problem,  in drivers and to invest in the specific training of agents to detect them -perhaps training drug recognition experts, as an example of the strategies used by some developed countries. 45,46 One of the limitations of this study is the fact that it was conducted exclusively with drivers who were not be allowed to return to the road and continue driving, which prevents comparisons with a control group.
Another limitation is the fact that data were collected on the roadside, where time and infrastructure for data collection is limited. This study therefore lacks information regarding the personality and cognitive aspects of drivers, which would be important to better define the risky profiles among groups. However, even with a cross-sectional design and a small sample size, we were able to detect initial evidence that distinguishes between drivers committing different infractions, suggesting that drivers who refuse breath tests could be a high-risk group.

Conclusion
This study showed that drivers committing different