The prevalence of alcohol and other drugs in fatal road crashes in Victoria, Australia.

Background: Driving under the influence of drugs, including alcohol, is a globally recognised risk factor for road traffic crashes. While the prevalence of alcohol and other drugs in fatal road crashes has been examined in other countries, recent data investigating drug driving in fatal Australian crashes are limited. This study aimed to examine how the presence of alcohol and other drugs in fatal road trauma in Victoria has changed over time in different road users.

Methods: A population-based review of road trauma deaths was performed over the period of 01 July 2006 to 30 June 2016 in Victoria, Australia, using data from the National Coronial Information System (NCIS) and the Victorian State Trauma Registry (VSTR). Drugs were grouped according to type and analysed accordingly. Poisson regression models were used to determine change in incidence rates over the study period.

Results: There were 2287 road traffic fatalities with complete toxicology data (97% of all road traffic fatalities). Alcohol (blood alcohol concentration, BAC) was the most commonly detected drug (>0.001 g/100 mL: 21.1%; >0.05 g/100 mL: 18.4%), followed by opioids (17.3%), THC (13.1%), antidepressants (9.7%), benzodiazepines (8.8%), amphetamine-type stimulants (7.1%), ketamine (3.4%), antipsychotics (0.9%) and cocaine (0.2%). Trends demonstrated changing use over time with specific drugs. Alcohol positive road fatalities declined 9% per year in passenger car/4WD drivers (IRR = 0.91, 95% CI: 0.88-0.95). The incidence of strong opioids (oxycodone, fentanyl, morphine, and methadone) increased 6% per year (IRR = 1.06; 95% CI: 1.02-1.10). Methylamphetamine was detected in 6.6% of cases and showed a yearly increase of 7% (IRR = 1.07; 95% CI: 1.01-1.13). The incidence of THC remained unchanged over the period, observed in 13.1% of cases. Stronger opioids were more commonly detected among pedal cyclists (19.0%) and pedestrians (20.9%) while THC was more commonly detected among motorcyclists (19.8%) and other light vehicle drivers (17.6%).

Conclusions: A decline in the prevalence of alcohol in fatalities suggests that law enforcement and public health strategies in Australia to address road fatalities and drink-driving may have had a positive effect. However, increases were observed in the incidence of other potentially impairing drugs including opioids and amphetamines, specifically methylamphetamine, indicating a concerning trend in road safety in Victoria that warrants further monitoring.