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Prevalence of Drug Use in Injured British Columbia Drivers.

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Author(s): Jeffrey R Brubacher, Herbert Chan, Walter Martz, Mark Asbridge, Rollin F Brant, Stirling Bryan, Jeffrey Eppler, Adam Lund, Olaf H Drummer, Scott A MacDonald, Robert E Mann, Roy A Purssell, William E Schreiber

Slidedeck Presentation:

2B Brubacher_Prevalence of Drug Use in Injured British Columbia Drivers

Abstract:

Background.

Impaired driving is a major public health problem but drug impaired driving remains poorly understood. Canadian roadside surveys and coroner’s data suggest that drug driving may be as prevalent as drunk driving. A study from the 1980s found that drug use was common in injured drivers treated in a Toronto trauma centre but the prevalence of drug use by injured Canadian drivers has not been studied recently. This study is part of an ongoing project investigating the role of cannabis in causing motor vehicle crashes.

To determine the prevalence of drug use in a sample of injured drivers treated in British Columbia trauma centres.

This study was approved by our institutional research ethics board. Drivers treated in the Emergency Departments (ED) at three participating BC trauma centers (2010 – 2012) were identified prospectively. Blood remaining after clinical use was obtained before it was discarded and analyzed at the BC provincial toxicology laboratory to determine the presence and concentration of cannabis, alcohol and other drugs that could impair driving ability.

Results.

To date, 1055 drivers met the study criteria and had blood analyzed. The average age of these drivers was 42.9 years (median = 43, IQR = 26.25 -55), 63.2% were male. Almost one third (31.9%) were admitted to hospital. Alcohol was present in 18.2% of drivers. Most alcohol positive drivers (88%) had an alcohol concentration > 0.08%. The second most common recreational drug detected was cannabis: 11.7% of drivers tested positive for cannabis metabolites and 7.1% were positive for THC (indicating recent use of cannabis). Cocaine was positive in 2.9% of drivers and amphetamines in 2.3%.  Medications including sedative hypnotics (6.2%), antidepressants (6.4%) and diphenhydramine (12.5%) were also detected.

Conclusions.

Alcohol, cannabis and other impairing drugs are commonly detected in injured BC drivers. Alcohol is well known to cause crashes but further research is needed to determine whether drivers who use other drugs are more likely to cause crashes.