The involvement of prescribed drugs in road trauma.

Coroners files and toxicological records of fatally-injured drivers in Victoria from 2000 to 2006 and from 2007 to 2013 were reviewed in separate studies to establish the role of prescribed drugs on crash risk. 2638 driver fatalities were included in the study, which represented over 97% of all driver fatalities in this period. The detection limits of the drugs were at the low end of those seen with common illicit drugs or prescribed drugs. Drugs of any type were found in 34.4% of the study group, medicinal drugs 21.2%, and alcohol (≥0.05 gram/100mL) was found in 24.8%. The prevalence of the most common drugs detected that are legally available by prescription were anti-depressants (7.9%), benzodiazepines (7.0%), opiates/opioids (6.6%), and sedating anti-histamines (1.1%). Each driver was assessed for responsibility using a previously published and validated method. The crash risk of drivers taking opioids, benzodiazepines, or anti-depressants (primarily the serotonin reuptake inhibitors), were not significantly over-represented compared to the drug-free control group, although there was a suggestion of increased crash risk for benzodiazepines. Crash risk was elevated for drivers using cannabis (by presence of THC in blood at>2ng/mL) and amphetamines. These data show that drivers using medicinal drugs alone are unlikely to show significant crash risk even if drugs are potentially impairing.