Odds of culpability associated with use of impairing drugs in injured drivers in Victoria, Australia
Introduction
Drugs capable of impairing key functions required for safe driving of motorized vehicles are one of several factors that increase crash risk. Globally, it is estimated that in 2013 there were over 188,000 alcohol-related road traffic deaths and a further almost 40,000 drug-related road traffic deaths (Poznyak, 2016). Drug use by drivers in the State of Victoria, Australia is also prevalent in both injured and killed drivers (Drummer et al., 2012, 2003; Di Rago et al., 2019b).
It is well recognized that around the world the drugs most capable of causing impairment, after alcohol, are illicit substances, particularly amphetamines, cannabis, and cocaine, although opioids and benzodiazepines are commonly associated with traffic injuries and death, and often in combination with other substances, including to some degree the novel psychoactive substances (NPS) (Gadegbeku et al., 2011; Movig et al., 2004; Li et al., 2013; Legrand et al., 2012; Bernhoft et al., 2012; Morland et al., 2011).
While there is little dispute that most of the drugs used recreationally can cause significant reduction in cognitive and psychomotor functions there is still some doubt over the extent that these drugs affect crash risk. Estimates of crash risk arise from three main types of analyses; i) by estimating the prevalence of specific drugs or drug classes in drivers that have crashed compared to drivers that have not had a collision (Movig et al., 2004; Mura et al., 2003; Hels et al., 2013), ii) from culpability analyses (sometimes called responsibility analyses) where the proportion of culpable drivers using a particular drug is compared to the proportion of drivers not using drugs (Gadegbeku et al., 2011; Drummer et al., 2004; Poulsen et al., 2014; de Carvalho et al., 2016; Dubois et al., 2015; Reguly et al., 2014; Laumon et al., 2005) and iii) from data obtained from population databases and registries (Dischinger et al., 2011; Corsenac et al., 2012; Leveille et al., 1994; Meuleners et al., 2011; Monarrez-Espino et al., 2016).
Meta-analyses of published studies generally show increases in crash risk, particularly for users of amphetamines (e.g. methylamphetamine and amphetamine) and cocaine (Elvik, 2013). The presence of THC in blood shows a more modest increase in crash risk with estimates (as odds ratios, OR) ranging from not significant to over 2, with most OR showing a less than doubling when adjusted for possible confounders (Gadegbeku et al., 2011; Li et al., 2013; Bernhoft et al., 2012; Hels et al., 2013; Drummer et al., 2004; Poulsen et al., 2014; Elvik, 2013; Martin et al., 2017; Asbridge et al., 2012). Crash risks for benzodiazepines and opioids are not so well established given both their prescribed and recreational use. Meta-analyses of published studies that include case control design, crash involvement or from determination of crash culpability show variable crash risk for these two classes (Elvik, 2013; Chihuri and Li, 2017; Dassanayake et al., 2011).
Culpability analysis has been used in several studies as originally reported (Robertson and Drummer, 1994) or with some variations in a number of subsequent studies (Gadegbeku et al., 2011; Drummer et al., 2004; Poulsen et al., 2014; Laumon et al., 2005; Brubacher et al., 2019; Longo et al., 2000). This has allowed an assessment of any changes to the proportion of culpable drivers within a number of categories including the effect of alcohol and various drugs summarized as an OR using the drug-free driver as the reference group. Changes in the OR may provide an estimate of the effect of drugs on crash risk providing any confounding factors can be accommodated in multivariate statistical calculations.
In the state of Victoria, the presence of methylamphetamine (MA), 3,4-methylenedioxy-methylamphetamine (MDMA) and Δ9-tetrahydrocannabinol (THC) has been prohibited in drivers of motorized vehicles. Since mid 2009 Victoria has legislated compulsory drug testing of all drivers hospitalized as a result of a road traffic collision. Approximately 5000–6000 blood specimens are analyzed at the Victorian Institute of Forensic Medicine annually for alcohol (ethanol), THC, MA and MDMA in accordance with the Victorian Road Safety Act (1986).
Blood specimens collected following a collision under the Victorian Injured Driver Drug Testing Program provide an excellent ongoing opportunity to add to the body of evidence surrounding drug use trends and insight to crash-risk among Victorian drivers through use of culpability analysis.
This study estimates the odds of culpability of drivers with detected drugs in Victorian injured-drivers hospitalized over the 5-year period to mid 2018 using a previously validated culpability method of determining driver contribution to a crash.
Section snippets
General
A blood specimen was taken from each driver admitted to a Victorian hospital (includes attendance at emergency units at hospitals) as a result of a road traffic crash as part of the State’s legislative requirements. Blood was collected by a medical practitioner or registered nurse at each hospital as soon as practicable after admission, and placed in sample tubes containing preservative (1 % sodium fluoride/potassium oxalate).
As part of this project 1000 drivers from each of the 5-year periods
Results and discussion
Of the 5000 cases analyzed 12 were subsequently excluded since they were later found not to be drivers. This left 4988 drivers, of which 63.1 % were positive to alcohol and/or one of the detected drugs. Details of the presence of these drugs in injured drivers have been detailed elsewhere (Di Rago et al., 2019b).
Both age and gender affected the odds of being responsible among drivers injured in a crash (Drummer et al., 2004; Chihuri and Li, 2019) (Table 1). Drivers aged between 40 and 59 years
Conclusion
This culpability analysis of almost 5000 injured drivers has provided further evidence of the elevated odds of culpability associated with alcohol and methylamphetamine using drivers as well as drivers positive to THC, particularly those with higher blood concentrations. Of all the legally-available drugs benzodiazepines used in isolation show a modest increase in culpability but are most often associated with other potentially impairing drugs.
Submission declaration and verification
This manuscript has not been published previously (except in the form of an abstract, or lecture), and it is not under consideration for publication elsewhere. This publication is approved by all authors and explicitly by the responsible authorities where the work was carried out, and that, if accepted, it will not be published elsewhere in the same form, in English or in any other language, including electronically without the written consent of the copyright-holder
Author contributions
Dimitri Gerostamoulos: Substantial contribution to the study conception and design, data acquisition, supervision of analyses and interpretation, drafting or revising the article for intellectual content. Revision of the article for intellectual content, approval of the final version.
Matthew Di Rago: Analytical analyses, data acquisition and analysis, revision of the article for intellectual content, approval of the final version.
Noel W. Woodford: Contribution to the study conception and
Declaration of Competing Interest
None.
Acknowledgements
The authors gratefully acknowledge the support of the Department of Justice, VicRoads, the Transport Accident Scheme (TAC) and Victoria Police that formed the Road Safety Executive (Victoria) and funded the study. In particular, gratitude is extended to William Gibbons (Department of Justice) and Inspector Tom McGillian (Victoria Police) for their support. We also thank Gemma Wynd of the Road Policing Drug and Alcohol Section of Victoria Police who assisted with data entry and culpability
References (55)
- et al.
Prevalence and risk of injury in Europe by driving with alcohol, illicit drugs and medicines
Procedia - Soc. Behav. Sci.
(2012) - et al.
Use of prescription opioids and motor vehicle crashes: a meta analysis
Accid. Anal. Prev.
(2017) - et al.
Road traffic crashes and prescribed methadone and buprenorphine: a French registry-based case-control study
Drug Alcohol Depend.
(2012) - et al.
The effects of cannabis and alcohol on simulated driving: influences of dose and experience
Accid. Anal. Prev.
(2013) - et al.
The prevalence of drugs in injured drivers
Forensic Sci. Int.
(2012) - et al.
The incidence of drugs in drivers killed in Australian road traffic crashes
Forensic Sci. Int.
(2003) - et al.
The involvement of drugs in drivers of motor vehicles killed in Australian road traffic crashes
Accid. Anal. Prev.
(2004) - et al.
The combined effects of alcohol and cannabis on driving: impact on crash risk
Forensic Sci. Int.
(2015) Risk of road accident associated with the use of drugs: a systematic review and meta-analysis of evidence from epidemiological studies
Accid. Anal. Prev.
(2013)- et al.
Cannabis effects on driving lateral control with and without alcohol
Drug Alcohol Depend.
(2015)
Risk of severe driver injury by driving with psychoactive substances
Accid. Anal. Prev.
Prevalence of alcohol and other psychoactive substances in injured drivers: comparison between Belgium and the Netherlands
Forensic Sci. Int.
The effects of cannabis and alcohol on simulated arterial driving: influences of driving experience and task demand
Accid. Anal. Prev.
Drug use and fatal motor vehicle crashes: a case-control study
Accid. Anal. Prev.
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
Accid. Anal. Prev.
Drugs related to motor vehicle crashes in northern European countries: a study of fatally injured drivers
Accid. Anal. Prev.
Psychoactive substance use and the risk of motor vehicle accidents
Accid. Anal. Prev.
Comparison of the prevalence of alcohol, cannabis and other drugs between 900 injured drivers and 900 control subjects: results of a French collaborative study
Forensic Sci. Int.
The relationship between blood alcohol concentration (BAC), age, and crash risk
J. Safety Res.
The culpability of drivers killed in New Zealand road crashes and their use of alcohol and other drugs
Accid. Anal. Prev.
Dose related risk of motor vehicle crashes after cannabis use
Drug Alcohol Depend.
Examining the impact of opioid analgesics on crash responsibility in truck drivers involved in fatal crashes
Forensic Sci. Int.
Responsibility analysis: a methodology to study the effects of drugs in driving
Accid. Anal. Prev.
A meta-analysis of the crash risk of cannabis-positive drivers in culpability studies-Avoiding interpretational bias
Accid. Anal. Prev.
Medication use and the risk of motor vehicle collisions among licensed drivers: a systematic review
Accid. Anal. Prev.
Cannabidiol (CBD) content in vaporized cannabis does not prevent tetrahydrocannabinol (THC)-induced impairment of driving and cognition
Psychopharmacology (Berl.)
Acute cannabis consumption and motor vehicle collision risk: systematic review of observational studies and meta-analysis
BMJ
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