It is currently unclear whether roadside drug testing reduces cannabis impaired driving. The findings of the paper by Asbridge and colleagues (http://dx.doi.org/10.1136/bmj.e536) add weight to the argument that cannabis users should be deterred from driving while intoxicated because of the risk of injury or death to themselves and others. This systematic review of nine case-control studies and culpability studies found that recent cannabis use almost doubled the odds of having a motor vehicle crash (odds ratio 1.92, 95% confidence interval 1.35 to 2.73). The increased risk was marginally larger in better designed studies (2.21 v 1.78), in case-control rather than culpability studies (2.79 v 1.65), and in studies that examined deaths rather than injuries (2.10 v 1.74). The authors note that, although residual confounding is possible, their results are consistent with experimental evidence that cannabis use leads to dose related impairments in simulated driving, psychomotor skills, and on-road driving. Public health education about the dangers of driving while under the influence of cannabis is unlikely to be enough to deter cannabis users from driving – they will also need to be persuaded that they are at risk of their cannabis use being detected. Governments in Australia, western Europe, and the United States have therefore introduced roadside drug testing for cannabis ( and other drugs such as methylenedioxymethamfetamine and methamfetamine). The Australian state of Victoria, for example, introduced roadside drug testing for cannabis in 2004, and other Australian states and 13 states in the US have also done so. (Author/publisher)
Samenvatting