Objective To determine whether the acute consumption of cannabis (cannabinoids) by drivers increases the risk of a motor vehicle collision. Design Systematic review of observational studies, with meta-analysis. Data sources We did electronic searches in 19 databases, unrestricted by year or language of publication. We also did manual searches of reference lists, conducted a search for unpublished studies, and reviewed the personal libraries of the research team. Review methods We included observational epidemiology studies of motor vehicle collisions with an appropriate control group, and selected studies that measured recent cannabis use in drivers by toxicological analysis of whole blood or self report. We excluded experimental or simulator studies. Two independent reviewers assessed risk of bias in each selected study, with consensus, using the Newcastle-Ottawa scale. Risk estimates were combined using random effects models.

https://www.bmj.com/content/bmj/344/bmj.e536.full.pdf

Acute cannabis consumption and motor vehicle collision risk: systematic review of observational studies and meta-analysis

http://www.ukcia.org/research/DoseRelatedRiskOfCrashes.pdf

Dose related risk of motor vehicle crashes after cannabis use

http://grotenhermen.com/driving/drummer.pdf

The involvement of drugs in drivers of motor vehicles killed in australian road traffic crashes

The existing literature on the prevalence of drug driving, the effects of drugs on driving performance, risk factors and risk perceptions associated with drug driving was reviewed. The 12-month pre...

A review of drug use and driving: epidemiology, impairment, risk factors and risk perceptions

Objectives To evaluate the relative risk of being responsible for a fatal crash while driving under the influence of cannabis, the prevalence of such drivers within the driving population, and the corresponding share of fatal crashes. Design Population based case-control study. Participants 10 748 drivers, with known drug and alcohol concentrations, who were involved in fatal crashes in France from October 2001 to September 2003. Main outcome measures The cases were the 6766 drivers considered at fault in their crash; the controls were 3006 drivers selected from the 3982 other drivers. Positive detection of cannabis was defined as a blood concentration of Δ 9 tetrahydrocannabinol of over 1 ng/ml. The prevalence of positive drivers in the driving population was estimated by standardising controls on drivers not at fault who were involved in crashes resulting in slight injuries. Results 681 drivers were positive for cannabis (cases 8.8%, controls 2.8%), including 285 with an illegal blood alcohol concentration (0.5 g/l). Positive cannabis detection was associated with increased risk of responsibility (odds ratio 3.32, 95% confidence interval 2.63 to 4.18). A significant dose effect was identified; the odds ratio increased from 2.18 (1.22 to 3.89) if 0 9 tetrahydrocannabinol 9 tetrahydrocannabinol 5 ng/ml. The effect of cannabis remains significant after adjustment for different cofactors, including alcohol, with which no statistical interaction was observed. The prevalence of cannabis (2.9%) estimated for the driving population is similar to that for alcohol (2.7%). At least 2.5% (1.5% to 3.5%) of fatal crashes were estimated as being attributable to cannabis, compared with 28.6% for alcohol (26.8% to 30.5%). Conclusions Driving under the influence of cannabis increases the risk of involvement in a crash. However, in France its share in fatal crashes is significantly lower than that associated with positive blood alcohol concentration.

/pdf/cannabis-intoxication-and-fatal-road-crashes-in-france-54cg4s8zlq.pdf

Cannabis intoxication and fatal road crashes in France: population based case-control study

http://www.grotenhermen.com/driving/longo2.pdf

The prevalence of alcohol, cannabinoids, benzodiazepines and stimulants amongst injured drivers and their role in driver culpability: part ii: the relationship between drug prevalence and drug concentration, and driver culpability.

http://www.grotenhermen.com/driving/longo1.pdf

The prevalence of alcohol, cannabinoids, benzodiazepines and stimulants amongst injured drivers and their role in driver culpability Part I: the prevalence of drug use in drivers, and characteristics of the drug-positive group

Christine E. Hunter

Papers

The prevalence of alcohol, cannabinoids, benzodiazepines and stimulants amongst injured drivers and their role in driver culpability: part ii: the relationship between drug prevalence and drug concentration, and driver culpability.

The prevalence of alcohol, cannabinoids, benzodiazepines and stimulants amongst injured drivers and their role in driver culpability Part I: the prevalence of drug use in drivers, and characteristics of the drug-positive group