The incidence and characteristics of illicit drug related driver fatalities in Western Australia, 2000-2012

Evidence continues to accumulate of the impairing nature of illicit drugs on driving and the prevalence of use among crash and non-crash involved drivers. The prevalence of illicit substances among drivers varies with the type of substance and whether the driver was involved in a crash. For example, illicit substances of all types have been detected in up to 33% of fatally injured drivers with cannabis being the most frequently detected substance (Beasely, Beirness & Porath-Waller, 2011). Among non-crash involved drivers, between 4%-18% self-report having driven after using illicit drugs (AIHW, 2011), while up to 3.5% of drivers subject to a roadside oral fluids test in one Australian state have tested positive (Davey, Davies, French, Williams & Lang, 2005). Research has also identified that certain drivers have a higher risk of illicit drug-driving, including males (e.g., Blencowe, Pehrsson, Mykkanen, Gunar & Lillsunde, 2012), younger age persons (e.g., Clarke, Ward, Bartle & Truman, 2010) and those that engage in other on-road risk behaviours such as failing to wear a seat-belt (e.g., Beasley et al., 2011), drink-driving (Ashbridge, Poulin & Donato, 2005), and unlicensed driving (e.g., Boorman & Owens, 2009). Annual reporting of illicit drug driving in Western Australia (which commenced in 2008) is limited to fatally injured drivers and general descriptors such as the type of substance, age and gender of driver, road user status, and day of week. Unfortunately the reports fail to provide a detailed understanding of the trend and pattern of illicit drug involvement over time and associated driver and crash risk factors. This paper reports on the selected findings of a recent in-depth investigation of illicit drug-driving in Western Australia during the period 2000-2012. The findings of two of the study’s objectives to be considered in this presentation are: to document the incidence, trend and characteristics of illicit drug related motor vehicle driver and motorcycle rider fatalities; and the multivariate modelling of driver/rider and crash risk factors for an illicit drug driver/rider fatality.