Estimating the risk of driving under the influence of psychoactive substances. Proefschrift Rijksuniversiteit Groningen.

Driving under the influence is one of the most important causes of fatal traffic crashes, with alcohol being the most dangerous substance to be used in traffic. Drugs and medicines are also dangerous, generally comparable with a BAC of 0.05-0.08. Combined use of different substances leads to even higher risks. In the past decades, much research has been conducted into the risks of driving under the influence of alcohol. However, studies into the risks of driving under the influence of psychoactive substances other than alcohol are much less frequent. Some researchers regard case-control studies as the best method to study the risk of driving under the influence of psychoactive substances. An important disadvantage of case-control studies, however, is that they are expensive and hard to perform. Therefore, few of these studies have been carried out. In addition, the findings of the limited number of studies that has been performed differ considerably. This PhD study investigated why the findings differ so much and whether the existing research guidelines for case-control studies can offer a solution. This knowledge allows a more accurate estimate of the relative risk of driving under the influence of psychoactive substances