The prevalence and impairment effects of drugged driving in New Zealand

The purpose of the research was to establish a quantitative picture of the type and the extent of drugged driving in New Zealand and investigate the level of driving impairment produced by the most commonly used drugs, both legal and illegal. A stratified telephone survey (n=2,000) and internet survey (n=434) were conducted to explore the extent of drugged driving. Other than alcohol, the drugs most commonly taken prior to driving were strong opioid-based painkillers, antidepressant medication, anti-nausea medication, cannabis and anti-anxiety medication. A large proportion of drivers also reported taking combinations of different drugs prior to driving. Of the most commonly taken drugs, cannabis, opioid-based painkillers and benzodiazepines (typically used to treat anxiety or insomnia) have been associated with increased crash and driving-related impairment. The combination of drugs and alcohol leads to significantly higher crash risk and driving-related impairments. Between 25% and 50% of drivers who reported taking drugs admitted ‘drugged driving’ more than once a week over the last 12 months; for prescription drugs this most frequently occurred in the morning, while for illegal drugs this was typically in the evening