Drug use, impaired driving and traffic accidents

156 Pages·2014·1.69 MB·English

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INSIGHTS EN
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About the EMCDDA D S
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The European Monitoring Centre for Drugs and U 1
Drug Addiction (EMCDDA) is the central source and SE 4-9
confirmed authority on drug-related issues in Europe. , IM 26
For over 20 years, it has been collecting, analysing and P 4
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disseminating scientifically sound information on drugs IR Drug use,
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and drug addiction and their consequences, providing D
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its audiences with an evidence-based picture of the
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drug phenomenon at European level. IV
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The EMCDDA’s publications are a prime source of A
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information for a wide range of audiences including: D
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policymakers and their advisors; professionals and R
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researchers working in the drugs field; and, more F
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broadly, the media and general public. Based in Lisbon, IC and traffic
the EMCDDA is one of the decentralised agencies of A
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the European Union. C
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About this series T
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EMCDDA Insights are topic-based reports that bring S
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together current research and study findings on a co
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particular issue in the drugs field. This report provides d
a comprehensive European picture on illicit drugs and e
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medicines in connection with driving. itio
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Second edition
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Drug use,
impaired driving
and traffic
accidents
Second edition
Prepared by
Alain G. Verstraete, Sara-Ann Legrand
(Faculty of Medicine and Health Sciences, Ghent University, Belgium)
EMCDDA project group
Liesbeth Vandam, Brendan Hughes, Paul Griffiths
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This publication of the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) is protected by
copyright. The EMCDDA accepts no responsibility for any consequences arising from the use of the data
contained in this document. The contents of this publication do not necessarily reflect the official opinions of the
EMCDDA’s partners, any EU Member State or any agency or institution of the European Union.
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Luxembourg: Publications Office of the European Union, 2014
ISBN: 978-92-9168-687-2
doi:10.2810/26821
© European Monitoring Centre for Drugs and Drug Addiction, 2014
Reproduction is authorised provided the source is acknowledged.
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Contents
5 Foreword
7 Executive summary
9 Introduction
13 CHAPTER 1
M ethodological issues in determining the relationship between drug consumption,
impaired driving and traffic accidents
13 Experimental studies
19 Epidemiological studies
23 Conclusion
27 CHAPTER 2
Prevalence of drugs among drivers
27 Roadside surveys
28 Subsets of drivers
29 Occurrence of new psychoactive substances in drivers
30 Conclusion
33 CHAPTER 3
Effects and risks associated with drugs
33 Cannabis
42 Opioids
52 Amphetamines
60 Cocaine
63 Benzodiazepines and other medicines
88 Other synthetic psychoactive substances/medicines
94 Conclusion
97 Overall conclusion
101 Abbreviations
103 Appendix
121 References

I Foreword
The mobility provided by road transport, particularly the car, allows many Europeans to
enjoy a lifestyle characterised by flexibility and independence. However, if we count the
lives lost and injuries inflicted as a result of road traffic accidents, it is clear that these
benefits come at a price: the most recent statistics reveal that more than 28 000 people
die on European roads each year, while a further 1.34 million are injured.
In 2003, the European Union’s third Road Safety Action Programme set the ambitious target
of halving the number of road deaths in the European Union in 2010. For the now 28 Member
States of the Union, this would amount to approximately 27 500 lives lost on the roads.
Many of the accidents and deaths that occur on European roads are caused by drivers
whose performance is impaired by a psychoactive substance (alcohol, illicit drugs,
psychoactive medicines or a combination of these substances). In order to meet the 2003
Action Programme’s target of a significant reduction in fatalities in road traffic, it was
necessary to address risks associated with all components of the road transport system,
including driver performance. While public concerns with regard to illicit drugs and
medicines in traffic were growing, knowledge at that point was insufficient to address
these concerns.
When the 2003 Action Programme was introduced, it was estimated that about 25 % of
fatalities on European roads were the result of the influence of alcohol, but a lack of
comparable studies meant that the proportion due to the effects of illicit drugs or
psychoactive medicines was unknown. For this reason, the DRUID (Driving Under the
Influence of Drugs, Alcohol and Medicines) project was established, with the aim of
estimating the size of the problem and examining the range of countermeasures. The
DRUID project — part of the 6th Framework Programme — was established in October
2006, ran for 5 years and involved 38 consortium partners from 17 EU Member States and
Norway. The overall objective of the DRUID project was to provide scientific support to EU
road safety policymakers by making science-based recommendations concerning
responding to driving under the influence of psychoactive substances. It reported its
research results at the end of 2011.
The prevention of driving under the influence of drugs is included as one of the key actions
in the recent EU drugs action plan 2013–2016. As part of its aim to provide factual,
objective, reliable and comparable information on the drug situation and responses to drug
use in Europe, the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) is
updating its 2008 Insights publication on drug use, impaired driving and traffic accidents
with the findings from the DRUID project and published literature from 2007 to early 2013.
Together with the EMCDDA’s 2012 thematic paper Driving under the influence of drugs,
alcohol and medicines — findings from the DRUID project, the present report provides a
comprehensive European picture on illicit drugs and medicines in connection with driving.
Both the policymaker and the general reader will find here a commentary on the large
number of studies that have been published on the topic in recent years, allowing an
objective appraisal of the known effects of psychoactive substances on the ability to drive
and an assessment of the extent to which drivers impaired by such drugs are present on
the roads.
Although this edition of the EMCDDA Insights series does not intend to be definitive, I am
pleased to present what I hope will be seen as an important signpost towards more
effective solutions to the problem of driving under the influence of drugs.
Wolfgang Götz
Director, EMCDDA
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I Executive summary
This literature review provides a comprehensive report on the relationship between drug
use, impaired driving and traffic accidents. It describes methodological issues (Chapter 1),
presents the results of prevalence surveys among drivers and provides an overview of
findings from major international epidemiological surveys published since 2007
(Chapter 2) and gathers evidence from experimental and field studies of the relationship
between drug use, driving impairment and traffic accidents (Chapter 3).
The research methods can be broadly separated into experimental and epidemiological
studies. Every approach has its inherent advantages and disadvantages. Experimental
studies, in which the drug is administered in measured doses to volunteers, may be
conducted in a laboratory or a driving simulator or on the public road. They allow the
effects of a single factor to be measured, but can identify only potential risks, and in some
cases the results can be of limited value because of the use of non-realistic doses for
safety reasons or because of the drug use history of the volunteers or inter-individual
differences. Epidemiological studies examine the prevalence of drug use in various
populations. They include roadside surveys, studies assessing the prevalence of drugs in a
subset of drivers, accident risk studies, responsibility analyses, surveys among the general
population and pharmacoepidemiological studies. However, the study design means that it
is not possible to completely eliminate all risk factors other than that under examination
and which may be highly correlated with the risk factor of interest. The results of different
studies may not be comparable if, for example, different populations or different kinds of
samples are tested.
The results of experimental studies have indicated that several illicit drugs could have an
influence on driving performance; the effects of some, but not all, drugs are dose
dependent. Cannabis can impair some cognitive and psychomotor skills that are
necessary to drive. 3,4-Methylenedioxymethylamphetamine (MDMA) exerts both negative
and positive effects on performance, and studies investigating the effects of a
combination of alcohol and illicit drugs have found that some illicit drugs (e.g. cannabis)
can act additively with alcohol to increase impairment, while others (e.g. cocaine) can
partially reverse alcohol-induced impairment. MDMA can diminish some, but not all,
deleterious effects of alcohol, while other negative effects of alcohol can be reinforced. The
chronic use of all illicit drugs is associated with some cognitive and/or psychomotor
impairment, and can lead to a decrease in driving performance even when the subject is
no longer intoxicated. The results of experimental studies also show that some therapeutic
drugs can cause obvious impairment. Benzodiazepines, for example, generally have
impairing effects, but some types (whether long-, medium- or short-acting) cause severe
impairment, whereas others are unlikely to have residual effects in the morning. First-
generation antihistamines are generally more sedating than second-generation ones,
though there are exceptions in both groups. Tricyclic antidepressants cause more
impairment than the newer types, though the results of experimental tests after
consumption of selective serotonin reuptake inhibitors are not always consistent. In every
therapeutic class, however, some substances are associated with little or no impairment.
These therapeutic drugs should preferably be prescribed to those wishing to drive.
Epidemiological studies have confirmed many of the findings from experimental studies.
The Driving under the Influence of Drugs, Alcohol and Medicines (DRUID) project has
calculated that, on average, 3.48 % of drivers in the European Union drive with alcohol
(> 0.1 g/l) in their blood, 1.9 % with illicit drugs, 1.4 % with (a limited list) of medicinal
drugs, 0.37 % with a combination of alcohol and drugs and 0.39 % with different drug
classes. Studies assessing the prevalence of drugs, medicines and/or alcohol in drivers
who were involved in a traffic accident (fatal or otherwise) have found that alcohol is more
prevalent than any other psychoactive substance, but drugs are also frequently found, and
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Drug use, impaired driving and traffic accidents
in a higher proportion of drivers than in the general driving population. Of the drugs
analysed, cannabis is the most prevalent after alcohol, although benzodiazepines, when
samples have been analysed for these, are sometimes even more prevalent than cannabis.
Statistically, the use of amphetamines, cannabis, benzodiazepines, heroin and cocaine is
associated with an increased risk of being involved in and/or responsibility for an accident,
and in many cases this risk increases when the drug is combined with another
psychoactive substance, such as alcohol.
From the perspective of traffic safety — especially looking at prevalence rates and risks
— the following conclusions can be made. Alcohol, especially in high concentrations, must
remain the principal focus of prevention measures. The combination of alcohol and drugs
or medicines seems to be a topic that should be addressed more intensively because it is
associated with a very high risk of a traffic accident. The problems resulting from medicine
use among drivers should be addressed by providing doctors and patients with
appropriate information, not by defining thresholds. Based on experimental studies,
D9-tetrahydrocannabinol and amphetamines would appear to represent a minor risk, but in
case–control studies amphetamines use is associated with a much increased risk of
accident. More research is needed to investigate the probable risks of amphetamines in
real traffic and the mediating factors. From the perspective of risk, sleep deprivation
should also be addressed as it is associated with a high risk of accidents.
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