A comparison of the prevalence of cannabis and alcohol use among drivers and passengers in British Columbia and Ontario, Canada
研究比较了加拿大两省交通事故中驾驶员与乘客的酒精和大麻检出率，发现乘客酒精检出率高于驾驶员，安大略省驾驶员酒精检出率更高但大麻检出率更低，可能与交通政策和社会规范差异有关。
• A higher percentage of motor vehicle passengers than drivers had used alcohol. • No differences between passengers and drivers were observed for THC. • Alcohol detection was higher in drivers from Ontario than in drivers from BC. • THC detection was lower in drivers from Ontario than in drivers from BC. • These findings may be due to differences in traffic policy or societal norms. Similar to drink driving, the prevalence of driving under the influence of cannabis (DUIC) is expected to depend on the availability and cost of cannabis which would impact cannabis use in both drivers and passengers, and factors that specifically target cannabis use in drivers such as the deterrent effect of traffic laws and driver’s opinion about the risks and acceptability of DUIC. To disentangle these effects, we aimed to compare the prevalence of alcohol and tetrahydrocannabinol (THC) detection 1) in drivers vs. passengers involved in motor vehicle accidents and 2) in drivers and passengers from BC vs. Ontario. Chart review and toxicology data from an ongoing prospective study of moderately injured motor vehicle occupants were analyzed. Log-binomial regression models were used to obtain prevalence ratios (PRs). This manuscript reports on data from 3004 drivers and 941 passengers. Approximately half (55.1%) were male, and the mean (SD) age was 43.8 (19.1) years. Alcohol and THC detection prevalence was 14.2% and 12.4%, respectively. Passengers had higher prevalence of alcohol than drivers (aPR [95% CI]: 1.22 [1.06, 1.40]). No difference in THC prevalence was observed between drivers and passengers. Ontario drivers had higher prevalence of alcohol detection than BC drivers (aPR [95% CI]: 1.33 [1.13, 1.58]) but lower prevalence of THC detection (aPR [95% CI]: 0.80 [0.64, 0.99]). Among passengers, no significant interprovincial differences were observed for alcohol or THC detection. These findings may be partially explained by differences in provincial traffic laws, public opinion, and overall consumption rates.