Increased collision risk among drivers who report driving after using alcohol and after using cannabis

Sayer, Gillian; Ialomiteanu, Anca; Stoduto, Gina; Wickens, Christine M.; Mann, Robert E.; Le Foll, Bernard; Brands, Bruna · 2014 · OpenAlex-citations

DOI: 10.17269/cjph.105.4351

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Summary

This study investigates the self-reported collision risk among drivers in Ontario, Canada, who engage in driving under the influence of alcohol (DUIA) and/or cannabis (DUIC). While the increased collision risks associated with DUIA and DUIC individually are well-established, there is a significant gap in research regarding the prevalence and specific risks faced by individuals who report both behaviors. The authors aimed to address this by analyzing population-level data to determine if drivers reporting both DUIA and DUIC face a distinct or compounded risk compared to those reporting only one or neither behavior. The research utilized data from the CAMH Monitor, an annual repeated cross-sectional survey of Ontario adults. The study merged data from 2002 to 2010, resulting in a weighted sample of 16,224 adults aged 18 and older. Participants were categorized into three groups based on their self-reported driving behaviors in the previous 12 months: those who reported neither DUIA nor DUIC, those who reported either DUIA or DUIC, and those who reported both. The primary outcome was self-reported involvement in at least one collision during the same period. Statistical analyses included Chi-square tests to examine associations and logistic regression to estimate odds ratios while controlling for demographic factors such as age and region. The results revealed significant differences in collision prevalence across the three groups. Drivers reporting neither DUIA nor DUIC, comprising 91.3% of the sample, had the lowest collision prevalence at 6.7%. Those reporting either DUIA or DUIC (7.7% of the sample) had a significantly higher prevalence of 9.6% (p<0.01). The highest risk was observed in the group reporting both DUIA and DUIC (0.9% of the sample), with a collision prevalence of 30.5% (p<0.01). Logistic regression analysis confirmed these trends, showing that drivers reporting neither behavior were significantly less likely to experience a collision than those reporting one behavior (Adjusted OR = 0.74, 95% CI 0.56-0.98). Crucially, individuals reporting both DUIA and DUIC had over three times greater odds of collision involvement compared to those reporting only one substance use behavior (Adjusted OR = 3.65, 95% CI 2.12-6.28, p<0.001). The study concludes that drivers who self-report both DUIA and DUIC are at a particularly high risk for motor vehicle collisions. This finding highlights a vulnerable subgroup within the driving population that faces substantially elevated risks compared to those using only one substance or none. Although the data cannot distinguish whether these behaviors occur concurrently, the results underscore the importance of assessing combined substance use in public health strategies aimed at reducing traffic injuries. The findings suggest that interventions targeting drivers who use both alcohol and cannabis may be necessary to address this heightened risk profile.

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Topics

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• polydrug
• cannabis
• illicit drugs

Information type

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• Empirical Findings: crash risk outcomes, observational prevalence