Prevalence of alcohol and drugs among drivers killed in road traffic crashes in Norway during 2011-2020.

Driving under the influence of alcohol or drugs is one of the main contributing causes of serious road traffic crashes (RTCs). This study aimed to investigate the involvement of alcohol and drugs in driver fatalities in Norway during 2011-2020 and compare the findings with data from the previous decade. We linked the results of forensic toxicology testing for alcohol and the 17 most commonly used drugs assigned with legal limits with data on fatal road traffic crashes obtained from Statistics Norway and the Norwegian Public Roads Administration. The number of fatalities had decreased significantly since the previous decade, while the proportion of drivers and riders tested for alcohol and drug use increased. Blood alcohol concentrations at the legal limit or higher were found in 14.4% and psychoactive drugs were detected in 15.8% of the cases; 10.7% tested positive for illicit drugs, and 10.1% for medicinal drugs. The most prevalent illicit drugs were tetrahydrocannabinol (7.9%) and amphetamine/methamphetamine (4.7%), whereas the most prevalent medicinal drugs were clonazepam (3.7%) and diazepam (2.2%). There was a marked reduction in the number of motor vehicle drivers killed in RTCs compared with the previous decade, and also a reduction in the prevalence of alcohol. For other substances, there were no marked changes in the prevalence.