Risk of driving when positive for psychoactive substances

This paper aims to assess the risk of driving with alcohol, illicit drugs and medicines in various European countries. The risk of getting seriously injured or killed in an accident for a driver positive for a given substance was calculated with a case-control design as the odds ratio (OR) using logistic regression. For risk of serious injury, cases consisted of samples from 2,490 drivers admitted to hospitals in six countries and controls of 15,832 non-injured drivers from roadside surveys in the same countries. For fatality risk, cases consisted of 1,112 killed drivers in four countries and controls of 21,917 non-injured drivers from roadside surveys in the same countries. The risk estimates for serious injury and fatality for each substance were adjusted for age, gender and country. The results were based on risk estimates and their confidence intervals. The highest risk of getting seriously injured or killed was associated with BAC above 1.2 g/L and alcohol combined with other substances. Other high risk groups were drivers with BAC between 0.8 g/L and 1.2 g/L, multiple drugs and amphetamines. Medium increased risk was found for BAC between 0.5 and 0.8 g/L, cocaine, benzoylecgonine, illicit opiates and medicinal opioids. Slightly elevated risk was associated with cannabis and BAC between 0.1 g/L and 0.5 g/L. Risk of serious injury or fatality for drivers positive for the various substances was significantly above 1. However, high alcohol concentrations and the combination of alcohol and other drugs showed the highest risk and alcohol.