Research Studies Examine Prevalence of Drug-Impaired Driving, its Relation to Vehicle Crashes, and Improving Drug Identification and Evaluation

As drug-impaired driving becomes an issue of greater public concern, enforcement efforts based on solid research and evidence are becoming increasingly necessary. To this end, senior researchers from the Canadian Centre on Substance Abuse (CCSA) presented leading research on drugs and...

As drug-impaired driving becomes an issue of greater public concern, enforcement efforts based on solid research and evidence are becoming increasingly necessary. To this end, senior researchers from the Canadian Centre on Substance Abuse (CCSA) presented leading research on drugs and driving at the International Council on Alcohol, Drugs and Traffic Safety (ICADTS), held August 22-26 in Oslo, Norway.

The three different studies presented by CCSA indicate that drug use among drivers is as common as alcohol use, a significant number of fatal car crashes involved the use of drugs by drivers, and there are opportunities to streamline and improve the effectiveness of the system used to identify drug impairment among drivers.

Drug use is just as common as alcohol use among drivers, with 10.4 percent of drivers testing positive for drug use and 8.1 percent testing positive for alcohol, according to Alcohol and Drug Use Among Drivers: British Columbia Roadside Survey 2008. Presented by Douglas J. Beirness, CCSA Senior Research and Policy Analyst and Advisor, the survey was the first to simultaneously collect data on both drug and alcohol use among drivers. A second in-depth roadside survey on impaired driving was conducted in June 2010; research results and a final report are expected by the end of this year.

"The rate of driving after drug use is more prevalent than originally thought, and the 2008 and 2010 surveys provide us with a baseline assessment to evaluate any changes introduced to deal with the problem," said Beirness. "Illegal, prescription and some over-the-counter drugs can have serious effects on a variety of mental and motor abilities. As many of these abilities are critical to the safe operation of a motor vehicle, there is a real need for an impaired-driving awareness campaign that is inclusive of both alcohol and drugs."

Additional research presented by Beirness, A Comparison of Drug and Alcohol-involved Motor Vehicle Driver Fatalities, examined more than 14,000 driver fatalities in Canada from 2000-2006. Researchers found that 33 percent of drivers tested positive for at least one drug and 38 percent tested positive for alcohol. The most common drugs found in the blood of fatally injured drivers are depressants, stimulants and cannabis.

The results also reveal that fatal crashes involving drugs differ substantially from those involving alcohol. (For example, whereas alcohol-involved fatal crashes tend to occur on weekends and late at night, drug-related fatal crashes are more likely to occur during daylight hours throughout the week.) The research provides new evidence-based information to shape the development of prevention efforts and road safety. It could also allow enforcement officers to better identify drug-involved crashes and follow a course of action to investigate and prosecute those responsible.

In response to the increased concern from public health and road safety officials, the Federal Government passed Bill C-2, which empowers Canadian police who suspect a driver of being impaired by any drug-illegal, prescription or over-the-counter-to conduct a Standardized Field Sobriety Test. If the driver is impaired, they must submit to a mandatory Drug Evaluation and Classification (DEC) assessment-a standardized 12-step process that requires them to provide a bodily fluid sample.

The DEC assessment is conducted by Drug Recognition Experts (DREs)-police officers who have undergone intensive and specialized training. Research conducted by CCSA has demonstrated that DREs are 95 percent accurate in identifying the categories of drugs responsible for the impairment.

An extensive procedure that takes approximately 45 minutes to complete, the DEC assessment requires a DRE to analyze more than 100 pieces of information, including observations documented on divided-attention tests and various clinical indicators such as body temperature, pulse rate and the condition of the eyes.

In an effort to simplify the process, Dr. Amy Porath-Waller, CCSA Senior Research and Policy Advisor, presented research that analyzed DEC cases to identify whether a core set of signs and symptoms could be used to predict the categories of drugs used by suspected drug-impaired drivers. The study, Simplifying the Process for Identifying Drugs by Drug Recognition Experts, confirmed that DREs could focus on a limited set of clinical indicators without significantly compromising the accuracy of their drug evaluations. (Indicators related to the eyes were found to be particularly informative.)

"Simplifying the process of drug evaluation and identification may lead to increasing the effectiveness and efficiency of the DEC program and improving the enforcement of drug-impaired driving," said Dr. Porath-Waller. "The information on these clinical indicators in conjunction with what the DRE observes will contribute to an accurate assessment of drug impairment."

Enforcement is only one component of an overall strategy to tackle the persistent and growing problem of drug-impaired driving. Although there is much to be learned from years of experience in the area of drinking and driving, societal attempts to control drugged driving must recognize the substantial differences that exist and develop an innovative approach to deal with this issue. We also need a national drug impaired driving awareness campaign that is supported by a specific and targeted enforcement strategy using latest evidence-based drug identification and assessment approaches.

About CCSA:

With a legislated mandate to reduce alcohol- and other drug-related harms, the Canadian Centre on Substance Abuse (CCSA) provides leadership on national priorities, fosters knowledge translation within the field and creates sustainable partnerships that maximize collective efforts. CCSA receives funding support from Health Canada.

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