ArticleLiterature Review

Risk of road accident associated with the use of drugs: A systematic review and meta-analysis of evidence from epidemiological studies

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Abstract

A systematic review and meta-analysis of studies that have assessed the risk of accident associated with the use of drugs when driving is presented. The meta-analysis included 66 studies containing a total of 264 estimates of the effects on accident risk of using illicit or prescribed drugs when driving. Summary estimates of the odds ratio of accident involvement are presented for amphetamines, analgesics, anti-asthmatics, anti-depressives, anti-histamines, benzodiazepines, cannabis, cocaine, opiates, penicillin and zopiclone (a sleeping pill). For most of the drugs, small or moderate increases in accident risk associated with the use of the drugs were found. Information about whether the drugs were actually used while driving and about the doses used was often imprecise. Most studies that have evaluated the presence of a dose-response relationship between the dose of drugs taken and the effects on accident risk confirm the existence of a dose-response relationship. Use of drugs while driving tends to have a larger effect on the risk of fatal and serious injury accidents than on the risk of less serious accidents (usually property-damage-only accidents). The quality of the studies that have assessed risk varied greatly. There was a tendency for the estimated effects of drug use on accident risk to be smaller in well-controlled studies than in poorly-controlled studies. Evidence of publication bias was found for some drugs. The associations found cannot be interpreted as causal relationships, principally because most studies do not control very well for potentially confounding factors.

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... All these reductions may be dose-dependent (4), negatively influence driving skills and car crash risk, and may worsen with duration and frequency of cannabis use (5). However, results on the relationship between driving performance and traffic crash risk under the influence of cannabis revealed inconsistent findings (6)(7)(8). ...
... Methodological heterogeneity may explain mixed findings. As summarized by Asbridge et al. (2), several study types need to be considered for a comprehensive evaluation of the relationship between cannabis use, driving skills, and car crash risk [e.g., sample surveys, laboratory experiments, and epidemiological studies like case-control and their variant, "culpability" studies (2,7)]. Each of the study approaches has strengths and weaknesses. ...
... Among other factors which may contribute to crash risk under the influence of cannabis are the use of additional substances (e.g., alcohol) and the frequency and chronicity of cannabis use. Again, only a fraction of studies reports a combined assessment of various legal and illicit substances or controls for other confounding factors (7). ...
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In this review, state-of-the-art evidence on the relationship between cannabis use, traffic crash risks, and driving safety were analyzed. Systematic reviews, meta-analyses, and other relevant papers published within the last decade were systematically searched and synthesized. Findings show that meta-analyses and culpability studies consistently indicate a slightly but significantly increased risk of crashes after acute cannabis use. These risks vary across included study type, crash severity, and method of substance application and measurement. Some studies show a significant correlation between high THC blood concentrations and car crash risk. Most studies do not support this relationship at lower THC concentrations. However, no scientifically supported clear cut-off concentration can be derived from these results. Further research is needed to determine dose-response effects on driving skills combined with measures of neuropsychological functioning related to driving skills and crash risk.
... According to the WHO, road traffic collisions (RTC) account for about 1.3 million deaths and 20-50 million non-fatal injuries worldwide [1] and all over the world driving under the influence of psychotropic substances has become a widespread phenomenon. Despite driving under the influence of alcohol (DUIA) has been shown to increase the risk of involvement in RTCs, with relative risk increasing with blood alcohol concentration [2], less is known about the effects of medicinal and illicit drugs [3], and a clear correlation between drug concentrations and RTC risk is still debated [3,4]. Actually, the association between such substances (especially alcohol, amphetamines, cannabis, opioids and cocaine), impaired driving and road accidents has been extensively investigated so far [3], with results stating a link to an increased risk of car crashes and serious injuries not only to the impaired driver but also to other people, constituting a threat for public safety [5]. ...
... According to the WHO, road traffic collisions (RTC) account for about 1.3 million deaths and 20-50 million non-fatal injuries worldwide [1] and all over the world driving under the influence of psychotropic substances has become a widespread phenomenon. Despite driving under the influence of alcohol (DUIA) has been shown to increase the risk of involvement in RTCs, with relative risk increasing with blood alcohol concentration [2], less is known about the effects of medicinal and illicit drugs [3], and a clear correlation between drug concentrations and RTC risk is still debated [3,4]. Actually, the association between such substances (especially alcohol, amphetamines, cannabis, opioids and cocaine), impaired driving and road accidents has been extensively investigated so far [3], with results stating a link to an increased risk of car crashes and serious injuries not only to the impaired driver but also to other people, constituting a threat for public safety [5]. ...
... Despite driving under the influence of alcohol (DUIA) has been shown to increase the risk of involvement in RTCs, with relative risk increasing with blood alcohol concentration [2], less is known about the effects of medicinal and illicit drugs [3], and a clear correlation between drug concentrations and RTC risk is still debated [3,4]. Actually, the association between such substances (especially alcohol, amphetamines, cannabis, opioids and cocaine), impaired driving and road accidents has been extensively investigated so far [3], with results stating a link to an increased risk of car crashes and serious injuries not only to the impaired driver but also to other people, constituting a threat for public safety [5]. Indeed, the assumption of these substances may impair the visual, cognitive, and/or motor abilities needed for safe driving [6]. ...
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Driving under the influence of alcohol has been shown to increase the risk of involvement in road traffic collisions (RTCs) however, less is known about the effects of illicit drugs, and a clear correlation between drug concentrations and RTC risk is still debated. The goal of this narrative review is to assess the current literature regarding the most detected psychoactive drugs in RTC (ethanol, amphetamines, cannabis, opioids and cocaine), in relation to driving performance. Evidence on impaired driving due to psychoactive substances, forensic issues relating to the assessment of the impact of drugs, blood cut-off values proposed to date as well as scientific basis for proposed legislative limits are discussed. At present there is no unequivocal evidence demonstrating a clear dose/concentration dependent impairment in many substances. Per se and zero tolerance approaches seem to have negative effect on drugged driving fatalities. However, the weight of these approaches needs further investigation.
... and for injuries in accidents it was 1.44 (95% CI 0.93-2.23) [3]. Furthermore, multiple drug use involving cocaine is associated with a very increased risk [2][3][4], thus, constituting a great concern, especially if alcohol consumption is detected. ...
... [3]. Furthermore, multiple drug use involving cocaine is associated with a very increased risk [2][3][4], thus, constituting a great concern, especially if alcohol consumption is detected. ...
... Of note, polysubstance use was observed in over 8 out of 10 positive cases for cocaine and/or BZE. It is well known that there is a high risk for fatal and serious injuries from road accidents when driving with the presence of various drugs [2][3][4]. The implementation of roadside drug testing in association with an efficient punitive system could be an efficacious public health intervention for maintaining safe driving [1,5,13]. ...
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We are using real-life data in order to determine the prevalence of driving with the presence of cocaine and/or benzoylecgonine (BZE), their concentrations, and their use in combination with other drugs. This study assessed data on Spanish drivers with confirmed drug-positive results recorded by the Spanish National Traffic Agency from 2011–2016. Frequencies of positivity for cocaine and/or BZE and concentration of such substances were obtained. Comparisons and univariate and multivariate regression analyses were performed. Drivers who tested positive for cocaine and/or BZE accounted for 48.59% of the total positive results for drugs. In positive cases for both cocaine and BZE, other substances were detected in 81.74%: delta-9-tetrahydrocannabinol (THC) (68.19%), opioids (20.78%) and amphetamine-like substances (16.76%). In the multivariate logistic regression analysis, the frequency of cocaine and/or BZE positive cases decreased with age (OR:0.97) and were less likely among women (OR:0.63). Concentrations (ng/mL) of cocaine (249.30) and BZE (137.90) were higher when both substances were detected together than when detected alone. Positivity to cocaine represented an important proportion among Spanish drivers who tested positive for drugs, and polysubstance use was especially observed in more than 8 out of 10 positive cases for cocaine and/or BZE.
... Regarding the use of these drugs in the management of insomnia, the recommended maximum daily doses are provided by the national health authorities. Previous studies have found increased risk of considerable magnitude, but a meta-analysis from 2013 suggested a modest increased risk (17%) of involvement in traffic crashes with personal injury amongst users compared with non-users (Elvik 2013). To the best of our knowledge, no studies have investigated the effect of benzodiazepines and z-hypnotics or other psychotropics on the risk of a single traffic crash, defined as a crash involving only the user of psychotropics, with clear knowledge about their responsibility in the crash. ...
... However, in addition to antidepressant use, traffic crashes can also be attributed to depression itself as depressive symptoms impair cognitive functioning (Cameron and Rapoport 2016). A meta-analysis by Elvik suggested a 35% increased risk of traffic crashes involving personal injury from antidepressant use (Elvik 2013). Recent clinical studies have shown that modern antidepressants improve or at least stabilise the driving skills of persons with depression (Brunnauer et al. 2021;Laux 2013, 2017). ...
... Our study found a 29% increased risk of traffic crashes involving personal injury associated with the use of benzodiazepines and z-hypnotics, which is similar in magnitude to the result of a previous meta-analysis from 2013, indicating that the odds were increased by a modest 17% after adjustment for publication bias in the analysis of 51 effect estimates (Elvik 2013). A more recent Taiwanese study by Chang and colleagues found 56% and 42% increased risks of being involved in traffic crashes for persons who had filled a prescription of benzodiazepines and z-hypnotics, respectively (Chang et al. 2013). ...
Article
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Rationale Use of psychotropics is relatively prevalent amongst motor vehicle drivers because mobility is also important for persons suffering from psychiatric illness. However, medication side effects may increase the likelihood of being involved in traffic crashes. Objectives This study aimed to assess the association between the use of four types of medication (antipsychotics, benzodiazepines and z-hypnotics, antidepressants and stimulants of ADHD treatment) and the risk of traffic crashes, in general, and single crashes subsequently. Method We conducted a case–control study of data from 130,000 drivers involved in traffic crashes with personal injury and prescription data from all of Denmark during the period 1996–2018. Results For antipsychotics, we found odds ratios of 0.86 and 1.29 for traffic crashes and single crashes, respectively; for benzodiazepines and z-hypnotics, 1.29 and 2.49, respectively; for antidepressants, 1.30 and 2.25, respectively; and for stimulants of ADHD treatment, 1.62 and 1.95, respectively. All p values were below 0.001. Conclusions Based on our results on twofold increased risks of single crashes and moderately increased risks in persons with ADHD, it might seem tempting to ban psychotropic medication in traffic. Conversely, we accept increased risks of traffic crashes in young drivers and in the physically disabled with special aids and, to some extent, with exposure to alcohol. In the end, it is the authorities who must review the evidence and decide whether to prohibit (some types of) psychotropic medication in traffic. Finally, underlying disease and not the drug may increase the risk of being involved in a traffic crash.
... More precisely, BDZ slow the rate of information processing, impairing alertness and attention, visual processes, motor coordination, and memory. Collectively, these deficits may increase the likelihood of being involved in an accident, typically due to falls and motor vehicle collisions, the latter resulting from compromised steering, road positioning and reaction times, particularly for anxiolytic BDZ (Dassanayake et al., 2011;Elvik, 2013). However, while some evidences hint toward significantly increased risk for motor vehicle collisions compared with non-users (Barbone et al., 1998;Smink et al., 2010;Dassanayake et al., 2011;Elvik, 2013), and the use of BDZ has the potential to negatively affect the performance of safetysensitive tasks at work (e.g., driving and operating machinery), with eventually increased risk for occupational injuries (Guina and Merrill, 2018;Kowalski-McGraw et al., 2018), the role of BDZ in occupational injuries remains controversial. ...
... Collectively, these deficits may increase the likelihood of being involved in an accident, typically due to falls and motor vehicle collisions, the latter resulting from compromised steering, road positioning and reaction times, particularly for anxiolytic BDZ (Dassanayake et al., 2011;Elvik, 2013). However, while some evidences hint toward significantly increased risk for motor vehicle collisions compared with non-users (Barbone et al., 1998;Smink et al., 2010;Dassanayake et al., 2011;Elvik, 2013), and the use of BDZ has the potential to negatively affect the performance of safetysensitive tasks at work (e.g., driving and operating machinery), with eventually increased risk for occupational injuries (Guina and Merrill, 2018;Kowalski-McGraw et al., 2018), the role of BDZ in occupational injuries remains controversial. In fact, available evidence for occupational injuries in BDZ use is scant, particularly when compared with that drawn from studies on the contribute of opioids or alcohol on the risk for work-related injuries (López-Arquillos et al., 2017). ...
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Background: Benzodiazepines have been widely used in clinical practice for over four decades and continue to be one of the most consumed and highly prescribed class of drugs available in the treatment of anxiety, depression, and insomnia. The literature indicates that Benzodiazepine users at a significantly increased risk of Motor Vehicle accidents compared to non-users but the impact on injuries at workplace is not well-defined. We aimed to investigate whether use of benzodiazepine is associated with increased risk of occupational injuries (OI). Methods: PubMed, Embase, and Scopus databases were searched. A meta-analysis was performed to calculate odds ratio (OR) and 95% confidence interval (CI) among case controls, cross-sectional studies, either questionnaire or laboratory exams based. Results: A total of 13 studies met inclusion criteria, involving 324,168 OI from seven different countries, with an estimated occurrence of benzodiazepine positivity of 2.71% (95% CI 1.45–4.98). A total of 14 estimates were retrieved. Of them, 10 were based on laboratory analyses, three on institutional databases, while one study was based on questionnaires. Regarding the occupational groups, three estimates focused on commercial drivers (0.73%, 95% CI 0.12–4.30), that exhibited a reduced risk ratio for benzodiazepine positivity compared to other occupational groups (RR 0.109, 95% CI 0.063–0.187). Eventually, no increased risk for benzodiazepine positivity was identified, either from case control studies (OR 1.520, 95% CI 0.801–2.885, I2 76%), or cross sectional studies, when only laboratory based estimates were taken in account (OR 0.590, 95% CI 0.253–1.377, I2 63%). Conclusions: Even though benzodiazepines have the potential to increase injury rates among casual and chronic users, available evidence are insufficient to sustain this hypothesis, particularly when focusing on laboratory-based studies (i.e., studies the characterized the benzodiazepine immediately before the event).
... In many jurisdictions around the globe, the decriminalization and legalization of cannabis for medical and/or nonmedical purposes is increasing drug access, which has important public health implications, including those associated with road safety. Several meta-analyses concluded that cannabis use is associated with increased motor vehicle collision (MVC) risk (Asbridge et al., 2012;Elvik, 2013;Li et al., 2012;Rogeberg & Elvik, 2016). After alcohol, cannabis is the drug most frequently detected among seriously and fatally injured drivers (e.g., Brubacher et al., 2016; European Monitoring Centre for Drugs & Drug Addiction, 2014; Woodall et al., 2015). ...
... Understanding the potential impact of impulsivity on drug effects has important road safety implications. At present, although numerous meta-analyses identified an increased risk of MVCs associated with cannabis use (Asbridge et al., 2012;Elvik, 2013;Li et al., 2012;Rogeberg & Elvik, 2016), there is still significant debate about how cannabis increases collision risk and which cannabis users are most affected by that risk. It is important to identify all contributing factors, including personality and individual differences, to inform our understanding of these mechanisms and to develop targeted prevention countermeasures. ...
Article
A recent study of the impact of smoked cannabis on simulated driver behavior demonstrated a reduction in mean speed after smoked cannabis. Previous research identified an association between personality and individual differences and acute drug effects. The present study examined the impact of personality on the reduction in mean speed after smoking cannabis under single- and dual-task driving conditions originally reported by Brands et al. (2019). Sixty-one participants randomly assigned to the active drug condition completed a battery of self-report questionnaires measuring various personality constructs and subsequently operated a driving simulator before and 30 min after smoking a 12.5% Δ9-tetrahydrocannabinol (THC) cigarette. Linear regression modeling tested the influence of self-reported driving errors, lapses, and violations, driver vengeance, psychological distress, impulsivity, and sensation seeking on the reduction in speed after smoking cannabis. After adjusting for the influence of sex, blood THC concentration, and predrug mean speed, impulsivity was a significant predictor of change in speed under both single- (β = -.45, t = -3.94, p < .001) and dual- (β = -.35, t = -2.74, p = .008) task driving conditions after cannabis. Higher trait impulsivity was significantly associated with greater reductions in driving speed after cannabis use, which may reflect greater sensitivity to drug effects and a stronger compensatory response. Further multidisciplinary study, including neurochemical, genetic, and psychological components, would be beneficial in helping to better understand how impulsivity and other personality or individual differences may impact the effects of cannabis on driver behavior and performance. (PsycInfo Database Record (c) 2021 APA, all rights reserved).
... DUIC is even more common among Canadian youth, with 4.7% of Canadian students in grades 11 and 12 reporting DUIC in the past month (Minaker et al., 2017). Evidence is mounting that DUIC increases risk of motor vehicle collision, though the magnitude of this relationship is still a subject of debate (Asbridge et al., 2012;Elvik, 2013;Laumon et al., 2005;Mann et al., 2010;Martin et al., 2017;Rogeberg and Elvik, 2016;Watson and Mann, 2016;Wickens et al., 2019). In 2012, cannabis-attributable traffic collisions contributed to 75 deaths, 4407 injuries, and more than $1 billion in related costs in Canada (Wettlaufer et al., 2017). ...
... Evidence suggests that DUIC is detrimental to road safety (Asbridge et al., 2012;Elvik, 2013;Laumon et al., 2005;Mann et al., 2010;Martin et al., 2017;Rogeberg and Elvik, 2016;Watson and Mann, 2016;Wickens et al., 2019), and that the associated harms and costs suffered by society are potentially substantial (Wettlaufer et al., 2017). Considerable resources and effort have been dedicated to DUIC prevention activities (Government of Canada, 2018) which, in part, aim to raise awareness of the risks associated with DUIC. ...
Article
Driving under the influence of cannabis (DUIC) is detrimental to road safety. Risk perception is a strong determinant of DUIC behaviour, yet little is known about the factors influencing DUIC risk perception in the general population. The objective of this study was to identify factors associated with risk perceptions of motor vehicle collision and legal consequences due to DUIC and examine whether these perceptions were associated with DUIC behaviour. Data were derived from the 2017 CAMH Monitor, a cross-sectional telephone survey of adults aged 18+ years in Ontario, Canada (n = 1813). Multivariable logistic regression analyses were performed. Approximately 90% of adults overall agreed that DUIC increases motor vehicle collision risk compared to 55% of those reporting past-year DUIC. Being male, less educated, and using cannabis at least monthly were associated with disagreeing that DUIC increases motor vehicle collision risk. Being male, young, and using cannabis at least monthly were associated with agreeing that DUIC is safer than driving under the influence of alcohol (DUIA). Being male and using cannabis less than monthly were associated with agreeing that the chances of getting caught for DUIC are higher than DUIA. Safety but not legal risk perceptions were associated with DUIC behaviour among cannabis-using drivers. Cannabis legalization provides a timely opportunity for DUIC prevention strategies. This study suggests that policymakers should target male cannabis users and highlight the safety risks of DUIC. Further research is needed to assess the effectiveness of prevention measures and the impact of cannabis legalization on DUIC perceptions and behaviour.
... 13 The data regarding the greater prevalence of concurrent consumption of psychoactive substances in cases when compared with subjects of the comparison group are not unexpected and are consistent with other studies. 5,14 The combination of alcohol and other psychoactive substances (medicinal or illicit) causes a cumulative risk effect, 15 which increases the chance of accident. Cannabis and cocaine were the most frequently detected illegal substances in both groups, consistent with the prevalence of use of these substances in Italy. ...
... The joint use of cocaine and alcohol is another important risk factor for road accident involvement. 15 The presence of this substance reflects, as for cannabis, the prevalence of use in the general population. This data is confirmed by the fact that 13.38% (51 out of 381) of the cases involving cocaine use resulted in a judgment of unfit to drive during the medico-legal assessment. ...
Article
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A comparative case study (2017-2020) was conducted to identify demographic, social, medico-legal, and toxicological variables associated with non-fatal accidents in driving under the influence (DUI) subjects. A second aim was to identify the factors predictive of substance use disorders among subjects. Drivers charged with alcohol DUI (blood alcohol concentration (BAC) > 0.5) and/or psychoactive substance DUI were included; cases included those involved in an accident while intoxicated, and the comparison group included DUI offenders negative for road accident involvement. Significance was determined by chi-square and Mann-Whitney tests. To prevent confounding effects, a multivariate binary logistic regression analysis was performed. Our sample encompassed 882 subjects (381 in the case group and 501 in the comparison group). Parameters such as psychoactive substances and BAC at the time of the road crash/DUI and the day of the week, when subjects were involved in the road accident or found DUI, resulted in significant differences (p < 0.01) between groups. The model's independent variables of BAC > 1.5 g/L (p = 0.013), BAC > 2.5 g/L (p < 0.001), and concurrent alcohol and psychoactive substance use (p < 0.001) were independent risk factors for an accident. Smoking >20 cigarettes/day was an independent risk factor for unfitness to drive (p < 0.01). Unfitness to drive was based primarily on ethyl glucuronide levels >30 pg/mg. Our results suggest a detailed assessment of DUI subjects with variables associated with accidents (BAC > 1.5 g/L and concurrent intake of psychoactive substances). Hair analysis, including ethylglucuronide (EtG) concentration, should be always performed. Based on our results, nicotine use should be investigated in cases of driving license regranting.
... Figure 2. Relative increase in risk at increasing blood alcohol content (Blomberg et al., 2005). Table 2 shows the crash risk increase for illegal drugs as found in several metaanalyses (Els et al., 2019;Elvik, 2013;Hels et al., 2011;Rogeberg & Elvik, 2016;Rogeberg, 2019). The largest risk increase was found for amphetamines, multiple drug use, and combining alcohol and drugs. ...
... The largest risk increase was found for amphetamines, multiple drug use, and combining alcohol and drugs. Table 3 gives an overview of the increase in risk due to different medicines reported in various studies (Chihuri & Lee, 2017;Elvik, 2013;LeRoy & Morse, 2008). Significant risk increases have been found for driving under the influence of barbiturates (used for treating headaches, insomnia, and seizures), benzodiazepines (used to relieve anxiety and insomnia), antidepressants (used to alleviate depression). ...
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This report on impaired driving is part of a series of 20 thematic reports on road safety commissioned by the European Commission. The purpose is to give road safety practitioners an overview of the most important research questions and results on the topic in question. The level of detail is intermediate, with more detailed papers or reports suggested for further reading.
... Although cannabis consumption has the potential to substantially impair psychomotor skills and cognitive functionsreducing performance on critical tracking and divided-attention tasks, slowing reaction time and increasing lane weaving 1 -the influence of cannabis on driving tasks varies by individual, dose and methods of consumption, and time since consumption before driving. 2 Some studies have found associations between cannabis use and impairment of driving -including in driving simulators, closed-course driving and epidemiologic studies 3but others have not. 4 Furthermore, the findings of studies are frequently confounded by users' consumption of cannabis with other legal (e.g., tobacco, alcohol) and illegal (e.g., opioids, methamphetamines) substances, 3 making it difficult to estimate the relative contribution of cannabis consumption to motor vehicle collisions. This in turn leads to difficulty in establishing the optimal approach to educating both health care providers and the public about the effects of cannabis, so as to deter driving under the influence of cannabis. ...
... This is especially true in the face of the legalization of recreational cannabis, considering that increased access among young adults can increase DUIC (Parnes et al., 2018;Windle et al., 2019). Previous systematic literature reviews (SLRs) have synthesized the evidence around the relationship between cannabis consumption and MVC risk (Elvik, 2013;Asbridge et al., 2012;Li et al., 2012;Rogeberg et al., 2018), and the programs or campaigns aimed to address drugged driving in youth (Holmes et al., 2014). However, to our knowledge, no systematic literature review to date has synthesized and appraised the quality of evidence on the specific effects of cannabis on the driving performance of young drivers. ...
Article
Background Young drivers ages 15–24 continue to constitute a high-risk population for fatal motor vehicle collisions (MVCs) compared to all other age groups. Driving under the influence of cannabis is an important contributor to the high rates of MVCs among youth. Understanding the specific impact of cannabis on the driving performance outcomes of young drivers can inform injury prevention, education, and intervention strategies. Objectives This systematic literature review (SLR) aims to determine the Class (I- highest to IV-lowest) of evidence and level of confidence (A-high to U-insufficient) in the effects of cannabis on the driving performance of young drivers. Methods Registered in PROSPERO (#CRD42020180541), this SLR searched seven data bases and appraised the quality and confidence in the evidence using an established research methodology. Results Class II evidence suggests that THC is likely to reduce mean speed, headway distance, and reaction time; and increase lane and steering wheel position variability among young drivers (Level B, moderate confidence). Conclusions This study shows that there is a moderate to low level of confidence on the impact of cannabis on the specific driving performance outcomes of young drivers. A need remains for Class I and II studies that focus on the specific effects on young drivers, distinguish between the biological and socially constructed variables of sex and gender, and includes larger and more representative samples.
... Cannabis has generally been associated with some increased collision risk. Four meta-analyses have found increased collision risk for cannabis, although the odds ratios (OR) have varied from 1.10 to 2.79 (Asbridge et al., 2012;Elvik, 2013;Li et al., 2012;Rogeberg and Elvik, 2016). A recent meta-analysis of culpability studies on cannabis collision risk found an average increase in collision risk of 1.28 (1. ...
Article
Aims In recent years, many jurisdictions have legalized medicinal and/or recreational cannabis. Yet, limited information is available on the effects of cannabis commercialization (provision of legal supply of cannabis to adults through licensed retail outlets) on adverse outcomes, such as traffic fatalities. The purpose of this study was to systematically review the literature on the effects of cannabis retail outlets on traffic collisions, fatalities and other traffic-related outcomes. Methods Eight electronic bibliographic databases were searched (MEDLINE, PUBMED, PsychINFO, CINAHL, EMBASE, Scopus, Dissertation Abstracts, Google Scholar) to identify documents of original research on effects of cannabis retail outlets on traffic-related outcomes, including hand searches and a canvass of all members of the International Council on Alcohol, Drugs and Traffic Safety. The guidelines and rating criteria by the Scottish Intercollegiate Guidelines Network informed the review. Results 190 documents were identified, of which nine met all inclusion/exclusion criteria. All nine studies were conducted in the US. Six studies showed some increase in adverse traffic-related outcomes for states with legalized retail outlets compared to states with no legalized cannabis outlets. Three studies showed no overall effect, although one study showed a significant reduction in collision fatalities for those 15–44 years of age. Studies using Difference-in-Difference designs, total collision fatalities rates by billion vehicle miles travelled or by cannabis positive results found positive outcomes. Conclusions This systematic review indicates that two thirds of reviewed studies found some positive association between cannabis commercialization and fatality outcomes. However, the few studies available and the quality grading for the studies suggest only a moderate probability of causal attribution. Future studies need move beyond examining only fatalities or assessing mere presence of cannabis; reliable measures indicating driver impairment at time of collision are needed to establish better causal attribution and to provide greater utility for policy development and implementation.
... Même si la consommation de cannabis a le potentiel d'altérer substantiellement les habiletés psychomotrices et la fonction cognitive (réduction de l'efficacité aux tests de poursuite critique et aux tâches d'attention partagée et augmentation du temps de réaction et de la déviation de la trajectoire 1 ), l'influence du cannabis sur les tâches liées à la conduite varie selon les individus, la dose et le mode de consommation, ainsi que le temps écoulé entre la consommation et la conduite 2 . Certaines études ont établi une association entre l'utilisation du cannabis et la conduite avec facultés affaiblies, que ce soit sur des simulateurs de conduite, sur un circuit fermé ou dans le cadre d'études épidémiologiques 3 , mais d'autres n'ont pas mis en évidence de tels liens 4 . En outre, les conclusions des études sont souvent influencées par des facteurs de confusion comme la consommation de cannabis avec d'autres substances licites (p. ...
... In the past decade, a substantial body of research has documented an increased trend in crashes among youth caused by binge drinking, drug use, or the combination of binge drinking and drug use (Elvik, 2013). In 2015, the U.S. encountered the largest year-to-year percent increase (i.e., 7.2%) in crash fatalities in 50 years (National Highway Traffic Safety Administration, 2016b). ...
Article
Purpose: The purpose of this study was to identify and characterize trajectory classes of adolescents who ride with an impaired driver (RWI) and drive while impaired (DWI). Methods: We analyzed all 7 annual assessments (Waves W1-W7) of the NEXT Generation Health Study, a nationally representative longitudinal study starting with 10th grade (2009-2010 school year). Using all 7 waves, latent class analysis was used to identify trajectory classes with dichotomized RWI (last 12 months) and DWI (last 30 days; once or more = 1 vs. none = 0). Covariates were race/ethnicity, sex, parent education, urbanicity, and family affluence. Results: Four RWI trajectories and 4 DWI trajectories were identified: abstainer, escalator, decliner, and persister. For RWI and DWI trajectories respectively, 45.0% (n = 647) and 76.2% (n = 1,657) were abstainers, 15.6% (n = 226) and 14.2% (n = 337) were escalators, 25.0% (n = 352) and 5.4% (n = 99) were decliners, and 14.4% (n = 197) and 3.8% (n = 83) persisters. Race/ethnicity (χ2 = 23.93, P = .004) was significantly associated with the RWI trajectory classes. Race/ethnicity (χ2 = 20.55, P = .02), sex (χ2 = 13.89, P = .003), parent highest education (χ2 = 12.49, P = .05), urbanicity (χ2 = 9.66, P = .02), and family affluence (χ2 = 12.88, P = .05) were significantly associated with DWI trajectory classes. Conclusions: Among adolescents transitioning into emerging adulthood, race/ethnicity is a common factor associated with RWI and DWI longitudinal trajectories. Our results suggest that adolescent RWI and DWI are complex behaviors warranting further detailed investigation of the respective trajectory classes. Our study findings can inform the tailoring of prevention and intervention efforts aimed at preventing illness/injury and preserving future opportunities for adolescents to thrive in emerging adulthood.
... Det finnes oversiktsartikler som oppsummerer studier av effekter av ulike rusmidler på oppmerksomhet, reaksjonstid, og andre kognitive og psykomotoriske evner, og risiko for å bli involvert i trafikkulykker (3)(4)(5)(6). Nedenfor følger kort omtale av de viktigste trafikkfarlige rusmidlene og legemidlene. ...
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Aims of the study: To determine the prevalence of alcohol or drug impairment in fatal road traffic crashes in Norway during 2005-2018, primarily among fatally injured motor vehicle drivers (including riders), and assess the degree of impairment and prevalence of problematic use of alcohol or drugs. Alcohol and drug impairment was studied in relation to age, sex, time and place of crash, type of motor vehicle, type of crash, and type of driving errors. Methods: Data from the Crash Investigation Team Database operated by the Norwegian Public Roads Administration and forensic medicine data were used to obtain a comprehensive data set on killed drivers. Police data were used to generate statistics on killed and surviving road users involved in fatal crashes. Analytical findings of alcohol, illicit drugs and psychoactive medicinal drugs were assessed in relation to the legislative limits (corresponding to blood alcohol concentration (BAC) of 0.02 %) and limits for graded sanctions (corresponding to BAC of 0.05 % and 0.12 %) in the Road Traffic Act. Concentrations of alcohol or drugs in blood between BAC of 0.02 and 0.05 %, and corresponding values for drugs, indicate impairment in relation to the Road Traffic Act, but do not always indicate significant clinical impairment. Drivers with alcohol or drug concentrations corresponding to BAC of 0.05 % and higher, or high concentrations of amphetamines (5 times the legislative limits), were regarded as likely clinical impaired in this study. Results: The Crash Investigation Team had recorded that 22 % of fatal road traffic crashes during 2005-2018 were related to alcohol or drug impairment. In those crashes, 546 road users were killed. The numbers of fatal crashes in related to population were highest in the northernmost and southernmost regions. The majority of the fatal crashes that happened during the night and early morning were related to alcohol or drug impairment. The prevalence of alcohol and drugs was higher among drivers killed in road departures than in collisions between two or more vehicles. Of the killed car and van drivers, 66 % were investigated for alcohol or drug impairment by analysis of blood samples. Of those drivers, 35 % had concentrations of alcohol or drugs above the legislative limits given in the Road Traffic Act, 29 % had concentrations corresponding to BAC of 0.05 % or equivalent limits for drugs. Most of those drivers were significantly impaired, corresponding to a blood alcohol concentration of 0.12 % or more. A large proportion of those who were impaired by illicit drugs or psychoactive medicinal drugs had used two or more substances. The proportion of impaired drivers was higher among males than females, the highest proportion was observed among drivers below 40 years of age. The proportion of alcohol impairment among killed car and van drivers declined during the study period, but no significant change was observed for drugs. Information about alcohol and drug impairment that is not based on blood analysis is also recorded in the Crash Investigation Team Database. When combining those data with results from forensic testing, we estimated that at least 26 % of all killed car and van drivers were impaired by alcohol or drugs at the time of crash. Among killed MC and moped riders, 64 % had been investigated for alcohol or drug impairment by analysis of blood samples. Of those riders, 26 % had concentrations of alcohol or drugs above the legislative limits; 22 % had concentrations above 0.05 % for alcohol or equivalent limits for drugs. A slightly larger proportion tested positive for illicit drugs than among killed car and van drives. When combining forensic data with data from the Crash Investigation Team Database we estimated that at least 18 % of all killed MC and moped riders were impaired by alcohol or drugs at the time of crash. Among killed drivers of vans/lorries over 3500 kg, buses/minibuses and trucks, 7 % had concentrations of alcohol or drugs above the graded sanction limits corresponding to BAC of 0.05 %. Among drivers of other types of motor vehicles (ATVs, tractors, etc.), 31 % had concentrations of alcohol or drugs above those limits. Alcohol or drug impaired drivers and riders killed in road traffic crashes had often been speeding and not used seatbelt or MC helmet. Impairment by alcohol or amphetamines was strongest associated with those driving errors. Impairment by medicinal drugs was associated with non-use of seatbelt, but not with speeding. It was more difficult to assess driving errors associated with cannabis impairment, as most of those who tested positive for cannabis had also used alcohol or other drugs at the same time, substances that were likely to contribute to driving errors. Statistics from the police for the period 2016-2018 showed that few car and van drivers who were involved, but survived fatal crashes, were impaired by alcohol or drugs. Data also indicated that large proportions of killed bicycle riders and pedestrians were also impaired by alcohol or drugs corresponding to BAC of 0.05 % or more: 43 % of the bicyclists and 24 % of the pedestrians. However, those number may be inaccurate because few persons were included in the statistics. Among a total of 76 killed or surviving drivers of vans/lorries over 3500 kg, buses/minibuses and trucks, none were impaired. Four out of five impaired drivers involved in fatal road traffic crashes had previously been convicted for criminal offences, almost half of them for drink or drug driving. Conclusions: Test results from analysis of blood samples from drivers involved in fatal road traffic crashes indicate that the majority of those with alcohol or drug concentrations above the legislative limits had taken large doses or were multi drug users. This indicates problematic alcohol or drug use. The large proportion of drivers with previous convictions confirms this conclusion. It is important to take this fact into consideration when planning actions to reduce the prevalence of alcohol or drug impaired driving, as first time apprehension for drink or drug driving is a significant predictor for future impaired driving and involvement in road traffic crashes. The preventive effect of large fines, possible prison sentences, and suspension of the drivers’ license is insufficient. For this group of drivers, other preventive solutions must be used; both technical tools, training, and rehabilitation programmes may be used to change the drivers’ attitudes and behaviours.
... Moreover, in studies that reported driving impairment, marijuana use was associated with impairment of automatic driving functions of which drivers could not compensate for, and the risk of which increased with increasing doses (Ramaekers et al., 2009). On the other hand, other psychoactive drugs such as opiates, stimulants inhalant, and zopiclone have been associated with a higher risk of RTIs (Elvik, 2013;Gudaji and Dankishiya, 2016). At both the individual and societal level, alcohol consumption and psychoactive drug use represent a severe threat to road traffic safety (Lin and Kraus, 2009;WHO, 2015;Staton et al., 2018). ...
Article
Background Alcohol consumption and psychoactive drug use are well-recognised risk factors for road traffic injuries (RTIs). Both types of use may impair and affect drivers' performance. Yet, there is limited literature on their contribution to RTIs among commercial motorcycle riders, particularly in low- and middle-income settings. This study aimed to determine the association between alcohol consumption, marijuana use and RTIs among commercial motorcycle riders in the city of Dar es Salaam, Tanzania. Methods We conducted a case-control study between July 2018 and March 2019. Cases (n = 164) were commercial motorcycle riders who had sustained an RTIs and attended at a hospital. Controls (n = 400) were commercial motorcycle riders who had not experienced an RTIs that led to hospital attendance during the past six months. Alcohol consumption was assessed using the Alcohol Use Disorder Identification (AUDIT) score, which classified participants as a non-drinker, normal drinker(1–7 scores) and risky drinker (scores ≥ 8). Marijuana use was assessed through self-reported use in the past year. We estimated odds ratios (ORs) using logistic regression adjusted for sociodemographic, driver-, and work-related factors. Results Risky drinking was associated with close to six times the odds of RTIs compared to non-drinkers (OR = 5.98, 95% CI: 3.25 – 11.0). The association remained significant even after adjusting for sociodemographic, driving and work-related factors (OR = 2.41, 95% CI: 1.01 – 5.76). The crude odds ratios of RTIs were significantly higher among users of marijuana than non-users (OR = 2.33, 95% CI: 1.38 – 3.95). However, the association did not remain statistically significant after adjusting for confounders (OR = 1.11, 95% CI = 0.49–2.48). Conclusion Our findings confirm increased odds of RTIs among commercial motorcycle riders with risky drinking behaviour even after taking sociodemographic, driving and work-related factors into account. Unlike alcohol consumption the relationship between marijuana use and RTIs among commercial motorcycle riders was unclear. Since motorcycle riders are more susceptible to the effect of alcohol due to higher demands of balance and coordination and because commercial motorcyclist riders, in particular, they spend a considerable amount of time on the road, our results underscore the importance of addressing hazardous alcohol consumption and marijuana use in future prevention strategies to enhance road safety.
... Officials can use our outcomes for the control and prevention of road accidents [8]. Elvik [9] reviewed that road accident risks related to the usage of drugs and also meta-analysis has been conducted sixty-six studies recording a total of nearly 260 estimates of the accident risks involvement related to the drug usage while driving. Analyzed the accident in roads as per the condition of the road surface by using K-means clustering. ...
Chapter
The number of premature death due to road accidents (RA) in recent years has been on vertical horizon. In connection with this, this paper intends to identify, evaluate, and analyze various risks that aggregate the occurrence of RA. For this, through a literature survey and interaction with experts, three main risks, namely, engineering, human, and road-related risks, with a total of twenty-one sub-risks were identified and evaluated in a real-world setting. In this work, an integrated approach comprising both the Delphi method and the fuzzy Analytic Network Process (ANP) is used to evaluate the identified risks. Results reveal that non-uniformity, distracted driving, speeding, tire blowout, and using gadgets are the top five risks triggering the occurrence of RA. This study is not only limited to Indian context, it could be applicable to other developing countries where similar socio-economic condition prevails. Finally, this work proposes managerial implications which could assist the government in providing accident-free road system.
... Evidence supporting the concept of behavioral toxicity (e.g., DiMascio and Shader, 1968;Hindmarch I, 1994) comes from epidemiological data. Albeit causal relationships can hardly be drawn, there is considerable evidence that the use of psychoactive drugs is associated with an increased risk of traffic injuries, with a particular concern regarding benzodiazepines and tricyclic antidepressants (e.g., Ray et al., 1992;Leveille et al., 1994;Mura et al., 2003;Barbone et al., 1998;Bramness et al., 2008;Dassanayake et al., 2011;Elvik, 2013). Especially elderly users of sedating antidepressants have a more than twofold increased risk of being involved in road traffic accidents (Ray et al., 1992;Leveille et al., 1994;Dassanayake et al., 2011). ...
Article
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Background Mobility is important for daily life functioning with particular challenges regarding road safety under pharmacological treatment in patients with a psychiatric disease. Methods According to PRISMA guidelines, a systematic literature search on PubMed database (January 1970 til December 2020) was performed. Primary endpoints were driving performance in on-road-tests, driving simulator performance or psychomotor and visual perception functions assessed to estimate fitness to drive according to legal regulations in patient studies. Results Forty studies were identified (1533 patients, 38% female, median age 45 years), more than 60% were cross-sectional and open label trials. Under steady state medication 31% (range 27%-42,5%) of schizophrenic or schizoaffective patients under antipsychotics, and 18% (range 16%-20%) of unipolar and bipolar patients under antidepressants showed severe impairment in skills relevant for driving. Data point to an advantage of second generation antipsychotics (SGAs) compared to first generation antipsychotics (FGAs) as well as modern antidepressants over tricyclic antidepressants (TCAs) with respect to driving. Most patients significantly improved or stabilized in driving skills within 2-4 weeks of treatment with non-sedative or sedative antidepressants. Diazepam significantly worsened driving the first three weeks after treatment initiation, whereas medazepam (low-dose), temazepam and zolpidem did not impair driving. In long-term users of sedating antidepressants or benzodiazepines impairments in on-road–tests were not evident. Conclusion Available evidence suggests that psychopharmacologic medicines improve or at least stabilize driving performance of patients under long-term treatment when given on clinical considerations. To enhance treatment compliance, existing classification systems of medicinal drugs concerning their impact on driving performance should also incorporate information about effects of long-term-treatment.
... 14 A recent metaanalysis showed an association between cannabis use and violence when considering individuals with severe mental illnesses 3 and lifetime combustible cannabis use was associated with a 2.12 hazard ratio of developing tracheal, bronchus, or lung cancer over nonusers. 15 The acute intoxicating effects of use have been associated with a higher risk of motor vehicle collision [16][17][18] and marginally associated with severe and fatal injuries. 5 Recently, several countries have been discussing the possibility of legalizing largescale commercial cannabis production and sale of cannabis for nonmedical use, sometimes called recreational use, after others had already established decriminalization and depenalization policies. ...
Preprint
MAIN FINDINGS (1) Cannabis legalization benefits: decreases in cannabis-related and general drug combat law and criminal costs; reduction in synthetic cannabis supply; product quality control; decline in black economies and possible decrease in other illegal drug buying; and tax revenue growths. (2) Legalization harms: increase of cannabis use and experimentation, cannabis-related disorders, accidents and hospitalizations; profit-driven cannabis potency increase. (3) Growing, yet incomplete, evidence exists to guide policy makers in minimizing cannabis-related harm and positively contribute to public health, if the legalization path is to be followed. (4) Public health-driven, and not profit-driven models, seem to be gathering the most benefits regarding non-medical cannabis legalization. (5) Most of the true public health effects of cannabis legalization is still unknown, for we are yet in the early ages of these policies and their implications. Future studies should address the medium/long term social, economic and health consequences of legalization policies. PROPOSAL FOR CANNABIS LEGALIZATION (1) Non-commercial centralised model with control of product price, production, supply, quality and potency (2) Establishment of regulatory obligations in retails cannabis sales and penalties for non-compliance mainly aimed at business managers (3) Publicity restrictions to protect against pro-cannabis messages (4) Education of the population about the use and the risks of consuming cannabis (5) Identify and treat vulnerable users (6) Restriction of possession amount and public use (7) Prohibition of working and driving while under the influence of the drug (8) Implementation of systematic evaluations of the policy, allowing for fast and flexible adaptations when required
... The duration of BDZ treatment is also known to be a risk factor for developing BDZ dependence. 3 BDZ treatment is known to be a risk factor for traffic accidents, 13 and long half-life BDZ anxiolytics are associated with a greater risk than short half-life BDZs. 14 Furthermore, the concomitant use of alcohol and BDZs was found to increase the accident risk 7.7 times. ...
Article
Full-text available
Background: Concern regarding the benefit/risk ratio of the long-term use of benzodiazepines (BDZs) and Z-drugs is increasing. To prevent the risk of dependence in BDZ long-term use, it is essential to understand the attitudes of patients and psychiatrists toward BDZ treatment. The aims of this investigation were to 1) obtain information on patients' attitudes with long-term BDZ use and their referring psychiatrists' attitudes toward BDZ treatment, including their perception of the difficulty of reducing the dose of BDZs, and 2) identify discrepancies between patients' and psychiatrists' perceptions. Methods: A brief questionnaire was constructed to investigate the attitudes of patients receiving BDZ treatment and their referring psychiatrists. Our sample comprised 155 patients who received BDZ treatment for more than one year and their referring eight psychiatrists. Both the patients and their psychiatrists completed our questionnaire between August 2017 and December 2017. Results: Of the patients, 13% felt that it was more difficult to reduce the dose of BDZs than their referring psychiatrists (type A discrepancy), while 25% felt that it was less difficult (type B discrepancy). In the multivariate logistic regression analysis, the female sex and both the patients' ("psychotherapy plus BDZs was necessary" and "it was necessary to increase the dose of BDZs") and psychiatrists' beliefs ("short-term prescription was justified") were associated with type A discrepancies. Type B discrepancies were associated with psychiatrists' beliefs that the patient's wishes justified the use of BDZs and that the cessation of treatment with BDZs would lead to the deterioration of their rapport with their patients. Conclusion: To overcome the discrepancies in the attitudes of patients and psychiatrists toward the cessation of BDZ treatment, it is necessary to promote patient-centered care involving patient psychoeducation and practice guidelines for the decision-making process. Further studies investigating the promotion of patient-centered care to reduce BDZ use are needed.
... Several studies in France (Hours et al., 2008) and around the world have been carried out about the link between the consumption of several medicines and the risk of road traffic crash (Elvik, 2013). Some drugs are identified as strongly associated to an increased risk of road crash, especially benzodiazepines which represent the most studied class in the literature (Orriols et al., 2011(Orriols et al., , 2019Nevriana et al., 2017;Engeland et al., 2007;Lai et al., 2014;Drummer et al., 2020;Gjerde et al., 2011). ...
Article
Background Whereas an increased risk of road traffic crashes has been highlighted as linked to some medicine consumptions, there is no available data on this risk according to the type of journey (private, commuting or mission). Drivers on occupational journey (commuting or mission) are likely to have different coping behaviors related to the use of medicines than drivers on private journey. The aim of our study was to investigate the association between exposure to ten classes of medicines and the risk of being responsible for a road traffic crash according to the type of journey (private, commuting or mission). Methods The data used came from three French national databases: the national police database of injurious crashes, the police reports and the national health care insurance database. A total of 179,269 drivers aged between 18 and 65 years old involved in an injurious crash in France between July 2005 and December 2015 were included in the analyses. Logistic regression models stratified by journey were used to estimate the Odds Ratios (OR) and 95 % confidence intervals (95 % CI), adjusted for potential confounding factors. Results Medicines exposure levels were generally lower for drivers during occupational journeys, the risk of being responsible for a road traffic crash seems to be higher on commuting or mission journeys than on private journeys for four medicines. Indeed, for antiepileptics the OR was 1.59 [1.01–2.51] for mission journeys, 1.63 [1.24–2.15] for commuting journeys, and 1.47 [1.25–1.73] for private journey. For psycholeptics the OR was 1.02 [0.80–1.28] for mission journey, 1.19 [1.03–1.39] for commuting and 1.17 [1.08–1.26] for private journey. For psychoanaleptics OR was 1.35 [1.02–1.78] for mission journeys, 1.37 [1.17–1.60] for commuting journeys and 1.26 [1.14–1.40] for private journeys. Finally, for other nervous system drugs OR reached 2.04 [1.35–3.07] for mission journeys compared to 1.43 [1.21–1.70] for private journeys. Conclusion Our results encourage the implementation of preventive measures about some treatments and diseases in the context of occupational journeys.
... From their own meta-analysis, Rogeberg and Elvik (2016a) obtained a summary adjusted cannabis-crash OR of 1.36 (1.2-1.6). They conducted QA of the included studies using a four-item measure of quality that had been developed by Elvik (2013) specifically for application to drug-crash studies. Only two of the four items, the adequacy of the measure of drug use and the adequacy of the controls for confounding factors, were straightforward measures of methodological rigour. ...
Article
Full-text available
The development of drug driving policies should rest on sound epidemiological evidence as to the crash risks of driving after using psychoactive drugs. The findings from individual studies of the increased risk of crashing from the acute use of cannabis range in size from no increase (and perhaps even a protective effect) to a 10-fold increase. Coherent cannabis-driving policies cannot readily be developed from such an incoherent evidence base. A weighted average measure of risk, as provided by a meta-analysis, might be useful. However, if the range of risks found in the cannabis-crash studies reflects the different ways that a variety of biases are being expressed, then the simple application of a meta-analysis might provide little more than an average measure of bias. In other words, if the biases were predominantly inflationary, the meta-analysis would give an inflated estimate of crash risk; and if the biases were predominantly deflationary, the meta-analysis would give a deflated estimate of risk.
... However, car crash injuries appeared strongly associated with a strong cannabis intake rather than regular use (Blows et al., 2005). Illicit drugs are counterproductive to accomplishing a complicated task like driving and increase the probability of a crash (Elvik, 2013;Jongen et al., 2016;Johannes Gerardus Ramaekers et al., 2006;Ronen et al., 2010). In a study conducted in Milan, the concentration of cannabis and cocaine within legal limits had a correlation with car accidents more than legal blood alcohol concentration (BAC) (Ferrari et al., 2018). ...
Preprint
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Montgomery County Police Department in Maryland hosted a cannabis intoxication impaired driving lab, to evaluate the driving behavior of medical marijuana users, pre and post cannabis consumption. A portable driving simulator with an eye-tracking device was used where ten participants drove a virtual network in two different events: a traffic light changing from green to yellow and the sudden appearance of a jaywalking pedestrian. An accelerated failure time (AFT) model was used to calculate the speed reduction times in both scenarios. The results showed that the participant speed reduction times are lower i.e., they brake harder post cannabis consumption, when they encounter a change in traffic light whereas there is no statistical difference in speed reduction times pre and post cannabis consumption, when they encounter a jaywalking pedestrian. The gaze analysis finds no significant difference in eye gaze pre and post cannabis consumption in both events.
... In 2019, nearly 2400 U.S. teens were killed and 258,000 were in emergency rooms for injuries in motor vehicle crashes (Centers for Disease Control and Prevention (CDC) and National Center for Injury Prevention and Control (NCIPC), 2020). A substantial body of research has reported that binge drinking, drug use, or the combination of binge drinking and drug use are central risk factors for the increased trend in crashes among youth (Centers for Disease Control and Prevention (CDC) and National Center for Injury Prevention and Control (NCIPC), 2020; Elvik, 2013). This is reflected by the fact that every day, about 1 alcohol-related crash death occurs every 51 min and 1 in every 5 alcohol-related crash deaths occur in passengers (National Highway Traffic Safety Administration, 2016b). ...
Article
Introduction For young drivers, independent transportation has been noted to offer them opportunities that can be beneficial as they enter early adulthood. However, those that choose to engage in riding with an impaired driver (RWI) and drive while impaired (DWI) over time can face negative consequences reducing such opportunities. This study examined the prospective association of identified longitudinal trajectory classes among adolescents that RWI and DWI with their later health, education, and employment in emerging adulthood. Methods We analyzed all seven annual assessments (Waves, W1–W7) of the NEXT Generation Health Study, a nationally representative longitudinal study starting with 10th grade (2009–2010 school year). Using all seven waves, trajectory classes were identified by latent class analysis with RWI (last 12 months) and DWI (last 30 days) dichotomized as ≥ once = 1 vs. none = 0. Results Four RWI trajectories and four DWI trajectories were identified: abstainer, escalator, decliner, and persister. For RWI and DWI trajectories respectively, 45.0% (N = 647) and 76.2% (N = 1657) were abstainers, 15.6% (N = 226) and 14.2% (N = 337) were escalators, 25.0% (N = 352) and 5.4% (N = 99) were decliners, and 14.4% (N = 197) and 3.8% (N = 83) persisters. RWI trajectories were associated with W7 health status (χ² = 13.20, p < .01) and education attainment (χ² = 18.37, p < .01). Adolescent RWI abstainers reported better later health status than RWI escalators, decliners, and persisters; and decliners reported less favorable later education attainment than abstainers, escalators, and persisters. DWI trajectories showed no association with health status, education attainment, or employment. Conclusions Our findings suggest the importance of later health outcomes of adolescent RWI. The mixed findings point to the need for more detailed understanding of contextual and time-dependent trajectory outcomes among adolescents engaging in RWI and DWI.
... It is essential to include alcohol-related crashes as they total more than 40 billion dollars in crash-related costs annually (Blincoe et al., 2015). A study by means of systematic review of studies assessing the risk of crashes due to other drugs such as cocaine and cannabis was conducted (Elvik, 2013). The results showed a significant effect of drugs on severe and fatal crashes compared with less critical crashes. ...
Article
Full-text available
Despite significant progress in reducing impaired driving, impaired drivers are still a public threat to themselves and others. Studying all types of drivers’ impairment is especially important as impairment in the literature has been mainly looked at from an angle of the driving under the influence (DUI). In other words, there is a definitional ambiguity regarding the impaired driving in the literature review. Addressing that unclarity is especially important as while many considered impaired driving such as distraction and fatigued driving are similar to DUI, they account for a higher proportion of fatalities on roadway, compared with DUI. Thus, first we highlight links between DUI and other impaired driving based on the literature review, and then this study highlighted factors associated with various impaired driving so drivers’ actions and behaviors could be addressed more efficiently. Here, in addition to DUI, impaired drivers are defined as whether drivers were fatigued, distracted, or under some emotional conditions at the time of crashes. Multinomial logit model (MNL) was extended to a model excluding or equating some coefficients across categories, making parameters’ estimates more robust. The analysis results highlighted, for instance, types of vehicles that the drivers own, drivers’ gender, age, seatbelt use, and various drivers’ actions such as failure to keep the proper lane and following too close are associated with various impaired drivers’ actions. These associations are expected to be related to unseen drivers’ characteristics that were not recorded at the time of crashes. This is one of the earliest comprehensive studies, investigating the association of various factors and different types of impaired driving.
... Several meta-analyses have examined the relationship between acute cannabis consumption and crash risk, and most (i.e. [1][2][3][4]), but not all (i.e. [5]) indicate that cannabis is associated with an increase in crash risk. ...
Article
Background and aims: Cannabis and alcohol are frequently detected in fatal and injury motor vehicle crashes. While epidemiological meta-analyses of cannabis and alcohol have found associations with an increase in crash risk, convergent evidence from driving performance measures is insufficiently quantitatively characterized. Our objectives were to quantify the magnitude of the effect of cannabis and alcohol-alone and in combination-on driving performance and behaviour. Methods: Systematic review and meta-analysis. We systematically searched Academic Search Complete, CINAHL, Embase, Scopus, Google Scholar, MEDLINE, PsycINFO, SPORTDiscus and TRID. Of the 616 studies that underwent full-text review, this meta-analysis represents 57 studies and 1725 participants. We extracted data for hazard response time, lateral position variability, lane deviations or excursions, time out of lane, driving speed, driving speed variability, speed violations, time speeding, headway, headway variability and crashes from experimental driving studies (i.e. driving simulator, closed-course, on-road) involving cannabis and/or alcohol administration. We reported meta-analyses of effect sizes using Hedges' g and r. Results: Cannabis alone was associated with impaired lateral control [e.g. g = 0.331, 95% confidence interval (CI) = 0.212-0.451 for lateral position variability; g = 0.198, 95% CI = 0.001-0.395 for lane excursions) and decreased driving speed (g = -0.176, 95% CI = -0.298 to -0.053]. The combination of cannabis and alcohol was associated with greater driving performance decrements than either drug in isolation [e.g. g = 0.480, 95% CI = 0.096-0.865 for lateral position variability (combination versus alcohol); g = 0.525, 95% CI = 0.049-1.002 for time out of lane (versus alcohol); g = 0.336, 95% CI = 0.036-0.636 for lateral position variability (combination versus cannabis; g = 0.475, 95% CI = 0.002-0.949 for time out of lane (combination versus cannabis)]. Subgroup analyses indicated that the effects of cannabis on driving performance measures were similar to low blood alcohol concentrations. A scarcity of data and study heterogeneity limited the interpretation of some measures. Conclusions: This meta-analysis indicates that cannabis, like alcohol, impairs driving, and the combination of the two drugs is more detrimental to driving performance than either in isolation.
... Of 141 traumatic motor vehicle accidents, 16 individuals were opium users and 6 were methadone users. Based on numerous studies, the individuals' ability to drive is easily impaired by the consumption of narcotics such as opium, benzodiazepines, and cannabis by almost well-known mechanisms (28)(29)(30)(31). ...
Article
Objective: Narcotic and alcohol use are recognized as the two important underlying factors in all types of trauma. In this study, the prevalence of opium consumption was investigated in traumatic patients who referred to Shahid Rahnemoon hospital in Yazd in 2018. Methods: In this descriptive cross-sectional study, 252 patients with trauma admitted to Shahid Rahnemoon Hospital from October to December 2018 were studied. In order to collect the data, a checklist was administered including the patients’ demographic information (age and gender), opium consumption, location of trauma, day of occurrence of trauma and cause of trauma. Results: The mean of patients’ age was 31.33 ± 19.46 years ranging from 2 to 90 years and 71.4% of them were males. The most common causes of trauma included accidents with motor vehicles (56%), falls from height (19.8%), and intimate partner violence (6%), respectively. Regarding opium consumption, 87.3% of patients did not use it, while 10.3% consumed opium. Narcotic abuse was significantly different with regard to the patients’ gender (P = 0.000) and age (P = 0.000). Conclusion: Opium consumption increases the risk of error and accident while driving. People on methadone treatment also show high-risk behaviors and are at greater risk of accidents.
Article
Introduction: Driving after cannabis use is associated with a number of risks. Examination of driving after cannabis use among young adults is particularly important, as young adults have the highest rates of cannabis use and among the highest rates of traffic crashes. The current study examines rates and correlates of driving after cannabis use among young adults (aged 18–25) who reported past month cannabis use. Methods: Participants were from Michigan and recruited through paid Facebook and Instagram advertisements between February and March 2018 (n=461). Results: Nearly a third (31.9%) of the sample reported driving after cannabis use in the past month. Young adults who were employed (aOR=1.872, p=0.045), had medical cannabis cards (aOR=2.877, p<0.001), endorsed coping reasons for use (aOR=2.992, p=0.007), and endorsed social/recreational reasons for use (aOR=1.861, p=0.034) had greater odds of driving after cannabis use. Students had lower odds of driving after use (aOR=0.573, p=0.011). Conclusions: Employment and having a medical cannabis card may be important risk markers for identifying individuals more likely to drive after use of cannabis. Prevention efforts could provide psychoeducation at dispensaries to individuals with medical cannabis cards about the risks of driving after use. Coping motives for cannabis use may also be useful in identifying young adults at the greatest risk of driving after use of cannabis.
Article
Background Opioids increase the risk of traffic crash by limiting coordination, slowing reflexes, impairing concentration and producing drowsiness. The epidemiology of prescription opioid use among drivers remains uncertain. We aimed to examine population-based trends and geographical variation in drivers’ prescription opioid consumption. Methods We linked 20 years of province-wide driving records to comprehensive population-based prescription data for all drivers in British Columbia (Canada). We calculated age- and sex-standardised rates of prescription opioid consumption. We assessed temporal trends using segmented linear regression and examined regional variation in prescription opioid use using maps and graphical techniques. Results A total of 46 million opioid prescriptions were filled by 3.0 million licensed drivers between 1997 and 2016. In 2016 alone, 14.7% of all drivers filled at least one opioid prescription. Prescription opioid use increased from 238 morphine milligram equivalents per driver year (MMEs/DY) in 1997 to a peak of 834 MMEs/DY in 2011. Increases in MMEs/DY were greatest for higher potency and long-acting prescription opioids. The interquartile range of prescription opioid dispensation by geographical region increased from 97 (Q1=220, Q3=317) to 416 (Q1=591, Q3=1007) MMEs/DY over the study interval. Implications Patterns of prescription opioid consumption among drivers demonstrate substantial temporal and geographical variation, suggesting they may be modified by clinical and policy interventions. Interventions to curtail use of potentially impairing prescription medications might prevent impaired driving.
Article
Traffic crashes are a significant public health concern killing more than 37,000 people each year in the U.S. Poly-drug impaired driving is a growing factor in many fatal crashes. Research has shown that cannabis and alcohol (separately and combined) impair driving ability and increase crash risk. Washington State legalized recreational cannabis in 2014 and has since seen a steady increase in adult use of cannabis, and relatedly, drivers testing positive for compounds associated with cannabis. This study examined the behaviors and culture (e.g., shared values and beliefs) associated with driving under the influence of cannabis and alcohol of a representative sample of adults in Washington State. Most adults (91%) reported they did not drive within 2 hr of consuming cannabis and alcohol, had a negative attitude about that behavior (81%), and believed it was unacceptable (83%). Those drivers who reported they did drive within 2 hr of consuming cannabis and alcohol had different beliefs, for example that using cannabis after having too much to drink would calm them down and sober them up. This study examined the relationship between attitudes, behavioral beliefs, perceived injunctive and descriptive norms, perceived control beliefs, values, and assumptions and driving within 2 hr of consuming cannabis and alcohol.
Article
One reality of transportation systems is that vehicular accidents can happen practically anywhere and at any time. An increasing body of research suggests though that spatial and/or temporal dependencies (i.e., clusters or hot spots) among accidents likely exist. Along with understanding where and when such spatiotemporal dependencies may occur, another important facet to consider is the geographic extent or area associated with the hot spots. For example, an accident hot spot may involve a small, isolated portion of the transportation system or a much more expansive geographic area. Better delineation and quantification of the morphological characteristics of accident hotspots can provide valuable decision support for planning for accident hot spot mitigation and prevention. As the size and shape of accident hot spots may evolve over time, the capability to track such dynamics is vital, especially with respect to the identification of processes effecting hot spot occurrence as well as assessments of the efficacy of efforts to mitigate factors underlying hot spot development. To this end, a Geographical Information Systems (GIS) based framework is outlined to facilitate the analysis of the morphological characteristics of hot spots over time. The analysis framework is applied to a case study of vehicular accidents reported over a two-year period to demonstrate its practical utility. The application results indicate that patterns of change in hot spot morphology can be effectively quantified and a variety of informative spatial and temporal patterns can be detected.
Article
Introduction As cannabis use rises among adults in the U.S., driving under the influence of cannabis represents a public health concern. Methods In 2020, public-use data from the National Survey on Drug Use and Health were examined, using an analytic sample of 128,205 adults interviewed between 2016 and 2018. The annual prevalence of driving under the influence of cannabis was computed overall, by state, by demographic group, and among cannabis users. Demographic, psychosocial, and behavioral correlates of driving under the influence were tested by multivariate logistic regression. Results The self-reported annual prevalence of driving under the influence of cannabis was 4.5% (95% CI=4.3, 4.6) among U.S. adults, ranging from 3.0% (Texas) to 8.4% (Oregon) in individual U.S. states. Among cannabis users, 29.5% (95% CI=28.6, 30.3) reported driving under the influence of cannabis; the predicted probabilities of driving under the influence of cannabis were highest for those with more frequent use, with daily cannabis users evidencing a 57% predicted probability. Among individuals with symptoms suggestive of a cannabis use disorder, the prevalence of driving under the influence of cannabis was 63.8% (95% CI=60.8, 66.6). Among cannabis users, those reporting driving under the influence of cannabis had higher odds of driving under the influence of other illicit substances, using other illicit drugs, taking part in illegal behavior, and suffering from mental distress, after adjusting for demographic characteristics and psychosocial/behavioral correlates. Conclusions Findings suggest that prevention efforts should focus on frequent and problem cannabis users and should include content related to other illicit drug use and other drug-impaired driving.
Article
Objective: Since 2012, 19 states and the District of Columbia have legalized the recreational use of marijuana for adults ages 21 and older. Marijuana use at any level can impair driving performance. Prior research on enforcement of the minimum legal marijuana use age of 21 (MLMU-21) laws is limited. The objective of the current study was to assess the ease of access to marijuana by underage patrons at recreational marijuana outlets in California, where recreational marijuana was legalized in 2016. Method: Pseudo-underage patrons were sent to 50 randomly selected licensed recreational marijuana outlets in the state to see if they could enter the outlet without showing a valid identification of their age. Results: Pseudo-underage patrons were required to show age identification to enter in 100% of the licensed recreational marijuana outlets visited. Conclusions: It appears that licensed California recreational marijuana outlets avoid selling marijuana to underage customers. One reason could be a strong incentive for recreational marijuana outlet owners and managers to avoid being shut down for an illegal activity. Practical Application: Underage youth are not obtaining marijuana at licensed recreational outlets. Future studies and cannabis enforcement agencies should investigate whether underage patrons attempt to use fake IDs at licensed marijuana outlets and whether youth are obtaining marijuana from illicit dispensaries or from social sources.
Article
Objective In response to the opioid crisis, health practitioners and patients are seeking effective non-opioid analgesic alternatives for treatment of non-cancer pain. Cannabis is being considered as an alternative to opioids for this purpose. This shift may result in an increase in combined use of these drugs, which may have important health implications, including those related to road safety. This study was designed to provide a population-based estimate of the prevalence of cannabis and/or prescription opioid use and their impact on collision risk. Method Based on data from a regionally stratified cross-sectional general population telephone survey of adults (18+ years) in Ontario, Canada conducted from 2010 through 2018 (N = 13,552), a binary logistic regression was conducted of self-reported past-year collision involvement, assessing demographic characteristics, year of interview, driving exposure, hazardous drinking, perceived general and mental health, and past-year use of cannabis and/or prescription opioids. Results Approximately 29.5 percent of respondents reported using either cannabis (11.1 percent) or prescription opioids (18.4 percent), whereas 3.8 percent reported using both cannabis and prescription opioids. Adjusting for potential covariates, relative to those who reported using either cannabis or prescription opioids, drivers who reported being users of both drugs faced more than a two-fold increase in their odds of past-year collision involvement (AdjOR = 2.29, 95% CI = 1.46–3.58, p < 0.001). Conclusions The identified increase in the odds of a crash among drivers who report use of both cannabis and of prescription opioids has important implications. Further research examining the impact of combined use on driver skills and behaviours is needed.
Article
Background Recent shifting attitudes towards the medical use of cannabis has seen legal access pathways established in many jurisdictions in North America, Europe and Australasia. However, the positioning of cannabis as a legitimate medical product produces some tensions with other regulatory frameworks. A notable example of this is the so-called ‘zero tolerance’ drug driving legal frameworks, which criminalise the presence of THC (tetrahydrocannabinol) in a driver's bodily fluids irrespective of impairment. Here we undertake an analysis of this policy issue based on a case study of the introduction of medicinal cannabis in Australia. Methods We examine the regulatory approaches used for managing road safety risks associated with potentially impairing prescription medicines and illicit drugs in Australian jurisdictions, as well as providing an overview of evidence relating to cannabis and road safety risk, unintended impacts of the ‘zero-tolerance’ approach on patients, and the regulation of medicinal cannabis and driving in comparable jurisdictions. Results Road safety risks associated with medicinal cannabis appear similar or lower than numerous other potentially impairing prescription medications. The application of presence-based offences to medicinal cannabis patients appears to derive from the historical status of cannabis as a prohibited drug with no legitimate medical application. This approach is resulting in patient harms including criminal sanctions when not impaired and using the drug as directed by their doctor, or the forfeiting of car use and related mobility. Others who need to drive are excluded from accessing a needed medication and associated therapeutic benefit. ‘Medical exemptions’ for medicinal cannabis in comparable jurisdictions and other drugs included in presence offences in Australia (e.g. methadone) demonstrate a feasible alternative approach. Conclusion We conclude that in medical-only access models there is little evidence to justify the differential treatment of medicinal cannabis patients, compared with those taking other prescription medications with potentially impairing effects.
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In addition to therapeutic benefits, cannabis also causes cognitive and psychomotor impairment in some individuals. Common acute adverse events can be cannabinoid-specific, such as those related to THC (e.g., dizziness, cognitive effects, anxiety, dry mouth) or specific to the route of administration (e.g., cough, phlegm, or bronchitis from smoking cannabis). The Diagnostic and Statistical Manual 5th Edition (DSM-5) has defined a cannabis intoxication syndrome and a cannabis intoxication delirium syndrome that may rarely result from medical cannabis use.
Article
Asleep/fatigued driving has proven to be a serious and persistent highway-safety problem. This study investigates aspects of this problem by studying the temporal changes in driver-injury severities in single-vehicle crashes that involve asleep/fatigued driving. To do this, random parameters logit models with unobserved heterogeneity in means and variances were estimated to compare injury-severities in asleep/fatigued crashes in Florida in 2014 and 2019. The estimated models are based on available police-reported crash data that include a wide variety of factors related to the spatial, temporal, and weather characteristics as well as vehicle characteristics, traffic information, harmful events, roadway attributes, and driver characteristics. The model estimates show that there were many statistically significant factors determining driver-injury severities resulting from asleep/fatigued driving, and that the effect of these factors on driver-injury severities has changed significantly over time, with many explanatory variables producing temporally shifting marginal effects. While asleep/fatigued driving crashes remain a serious safety concern, the empirical findings indicate (using model prediction simulations) that the resulting injury severities in crashes involving asleep/fatigued driving have declined between 2014 and 2019, likely reflecting the effectiveness of safety campaigns and ongoing improvements in vehicle safety technologies and highway safety features.
Article
Governments have been urged to adopt real‐time prescription monitoring in order to manage and reduce risks associated with the long‐term use of sleep and anti‐anxiety medications. Given this imperative, accessible psychological interventions for benzodiazepine (BZD) dependency and withdrawal are essential. The aim of this study was to understand how counsellors support clients assessed as suitable for community‐based drug withdrawal services to reduce their BZD use. Six BZD counsellors and two service coordinators were interviewed. Counsellors collaborated with their clients and prescribing doctors to develop individualised taper schedules that were in line with recommended clinical guidelines. Psychoeducation underscored a range of evidence‐based interventions, and a trauma‐informed approach was considered essential in working with clients to reduce their use of BZDs. Continuity in care was affected by the degree of prescribing doctor support for the taper. Counsellors reported that workforce sustainability was enhanced by quality clinical supervision and professional development opportunities. The role of counsellors in providing accessible, community‐based interventions for clients to reduce their use of BZDs was supported. Psychosocial support, combined with a medically supervised taper, has a strong evidence base and implications for client‐centred interventions are discussed.
Article
Motor vehicle driver fatalities (≥18 years) from the files at Forensic Science South Australia were reviewed from January 2008 to December 2018 for cases in which either positive blood sample for methamphetamine (MA) or an illegal blood alcohol concentration (BAC) >0.05g/100 ml were found. Three hundred driver deaths were found with MA detected in 28 cases (age range 21–62 years; ave. 37.8 years; M:F 23:5). Hundred and fifteen cases with a BAC > 0.05 g/100 ml were identified (age range 18–67 years; ave 35.7 years; M:F 95:20). No change was found in numbers of MA cases, although alcohol cases showed a significant decline (p < 0.001). Drunk driving‐related fatal crashes tended to occur in the evening (5 p.m. to 11 p.m.), while MA‐related fatal crashes had a longer peak extending from late evening until late morning (11 p.m. to 8 a.m.). This study has demonstrated that while roadside breath testing, legislative changes, and increased monitoring have resulted in reduced levels of drunk driving, similar safety countermeasures have had negligible effects on MA use in drivers. Continued monitoring of MA use by drivers will, therefore, be necessary to assess the possible effects, or not, of new countermeasures.
Article
Driving is a complicated process that demands coordination between a range of neurocognitive functions, including attention, visuo-perception, and appropriate judgment, as well as sensory and motor responses. Therefore, several factors may reduce the driving performance of an individual, such as sleepiness, distraction, overspeeding, alcohol consumption, and sedative drugs, all of which increase the hazard of motor vehicle accidents. Among them, drowsy driving is a major cause of traffic accidents, leading to more serious injuries as compared to other causes of major traffic accidents. Although sleep disorders have been highly associated among drowsy drivers, they are often untreated and unrecognized as a disease. In particular, obstructive sleep apnea and narcolepsy are some sleep disorders that are highly related to traffic accidents. Insomnia, which can cause inadequate sleep duration and promote sedative effects from sleeping pills, may also cause traffic accidents. These conditions are especially applicable to commercial bus or truck drivers, nocturnal workers, and shift workers, who are highly vulnerable to drowsy driving. Therefore, assertive screening and management of sleep disorders are necessary in general private drivers and relevant occupational drivers.
Article
Background & Objectives This study reports the prevalence and concentrations of sedative-hypnotic drugs as exemplified by benzodiazepines (BZD) and zolpidem (Z-hypnotic) in blood samples from drivers involved in road traffic accidents (RTA) in the Padova region of Italy. Another aim of the study was to estimate the prevalence of these drugs with concentrations in blood above the therapeutic intervals and above specific per se limits. Methods A total of 4,066 blood samples collected from drivers involved in RTA were analysed for the presence of alcohol, drugs of abuse and medicinal drugs with sedative-hypnotic properties. Prevalence of drivers positive for BZDs and zolpidem were reported according to the reporting limit of our laboratory (1 ng/mL) in a sort of zero tolerance approach and compared with the prevalence according to analytical cut-offs used in the “European Union’s research project on Driving Under the Influence of Drugs, Alcohol and Medicines” (DRUID). The impairment-based, per se limits adopted in Norway and in England and the values used to define “therapeutic ranges” in blood and in plasma/serum were also applied to the case study. Results 175 blood samples were positive for sedative-hypnotics above 1 ng/mL, with the following prevalence: diazepam 44%, nordazepam 41.8%, lorazepam 32.6%, zolpidem 28%, oxazepam 25.6%, alprazolam 16%, delorazepam 11,6%, lormetazepam 11,6%, temazepam 11.6%, clonazepam 11.6%, triazolam 6.9%, N-desalkylflurazepam 4.6%, bromazepam 2.3%. When applying DRUID analytical cut-offs, the prevalence of BZDs and zolpidem sharply decreases. Applying the impairing cut-offs used in Norway, 56% of positive samples were above the limits equivalent to a BAC of 0.2 g/L, 39% above the limits corresponding to 0.5 g/L, and 23% above the cut-off corresponding to 1.2 g/L. Only 1% of the drivers had drug concentrations above the per se concentration limits adopted in England and Wales [26].When comparing blood levels with therapeutic ranges in plasma, bromazepam, lormetazepam and delorazepam were often found above the highest limits. The adjustment of the concentrations with the plasma-to-blood ratios causes a significant increase of cases above the therapeutic ranges in plasma. Conclusions Sedative-hypnotic drugs are medicinal substances frequently identified in drivers involved in RTA, commonly in concentrations associated with driving impairment. Beside blood drug concentration, several factors have to be considered to conclude that a driver was impaired. The frequent association with alcohol, cocaine and other BZDs, confirms the abuse potential of these medications.
Article
Introduction: The aim of this study was to determine whether drivers who had received more traffic infringements were more likely to be at fault for the crash in which they were killed. Method: The current dataset was derived from the crash and traffic history records provided by the Queensland Department of Transport and Main Roads and Coroner's Court for every driver, with available records, who was killed in a crash in Queensland, Australia, between 2011 and 2019 (N = 1,136). The most common traffic offenses in the current sample were speeding, disobeying road rules, driving under the influence of drugs and alcohol, and unlicensed driving. Logistic regression models were used to compute odds ratios for the number of overall offenses, the number of specific offense types, and for specific offending profiles that were derived from the literature. Age, gender, and crash type were each controlled for by entering them into the initial blocks of the regression models. Results: After accounting for the variance associated with age, gender, and crash type, only the overall number of offenses and the number of unlicensed driving offenses predicted a significant change in a drivers' likelihood of being at fault for the crash that killed them. Furthermore, drivers who were identified as having versatile (i.e., multiple offenses from different categories) or criminal-type offense profiles (i.e., offenses that were considered to approximate criminal offenses) were each significantly more likely to be at fault for a fatal crash. Practical applications: This study provided an important contribution by demonstrating how a more nuanced approach to understanding how a driver's traffic history might be used to identify drivers who are more at risk of being involved in a crash (i.e., for which they were at fault). The implications of these findings are discussed with recommendations and consideration for future research.
Article
Price elasticities are widely used in transport planning, forecasting and appraisal. This paper presents the largest ever meta-analysis of price elasticities of travel demand based on 2023 elasticities drawn from 204 British studies published between 1968 and 2020. A large number of credible variations in elasticities emerge that add to the evidence base, challenge some official recommendations and are useful to practitioners. The paper also presents an original meta-analysis of the length of time until the long run is achieved, based on 386 observations obtained from 47 studies. This is an important complement to the price elasticity meta-analysis and it also challenges official recommendations. Whilst the research is based on British evidence, the insights of a methodological nature at the least are transferable to other contexts.
Article
Objective: The aim of the study is to identify and report the epidemiological patterns of substance use on fatal and non-fatal road traffic injuries (RTIs) in Latin America. Methods: A systematic review identified all published studies from January 2010 through October 2020. Twenty-eight studies were included from PubMed and SciELO databases. The Newcastle-Ottawa scale was used to assess the methodological quality of the studies. Results: The prevalence of alcohol consumption in fatal RTIs in studies where 100% of the target population were tested varies from 15.3% up to 55% in Brazil; with respect to non-fatal RTIs, it varies from 9.1% in car drivers in Brazil to 24.1% in emergency patients in Argentina. The most studied drug other than alcohol was cannabis, present in 6.5% up to 20.8% of non-fatal RTIs cases, but lower rates of testing for drugs was reported. Few studies reported epidemiological association measures. Conclusions: This article shows that scientific production on substance use and RTIs in the region is limited and reports the prevalence of substance use, with few estimates of the relative risk of drug use and RTIs.
Article
Background: Benzodiazepines, Z-drugs, pregabalin, and melatonin (BZPMs) have been associated with a higher risk of traffic accidents, but the evidence is inconsistent, and lacking for newer drugs. Aim: To examine the association of BZPMs with risk of traffic accidents. Methods: All Danish adults (n = 3,823,588) were followed for redeemed prescriptions of BZPM and for incident traffic accidents registered in Danish registers from 2002 through 2018. Associations were examined in cohort and case-crossover designs using Cox proportional hazard and conditional logistic regression with adjustment for co-variables. Results: A total of 19.3% (n = 738,019) of all participants initiated treatment with BZPMs. During the mean follow-up of 10.3 years, 595,173(15.5%) of participants were involved in a traffic accident. In the cohort analysis, all BZPMs besides pregabalin were associated with a higher risk of traffic accidents in adults below 70 years, with chlordiazepoxide showing the strongest association (hazard ratio (HR)age 18-49 = 1.76, 95% confidence interval (CI): 1.67-1.86 and HRage 50-69 = 1.84, 95% CI: 1.70-2.00). In the older age groups, the specific BZPM medications were associated with lower or no risk of traffic accidents. However, in case-time-crossover analysis with inherited control for confounders, no BZPM medication was positively associated with traffic accidents, except for chlordiazepoxide, which had a higher odds ratio in middle-aged group (1.62, 95% CI: 1.15-2.29). Conclusions: This study does not fully support that BZPM use is a risk factor for traffic accidents. However, a positive association was found for chlordiazepoxide, which is approved for treatment of acute alcohol withdrawal.
Article
Objective The purpose of this study was to determine the prevalence of cannabis, alcohol and other drug use in drivers of motor vehicles who died in crashes in the Canadian province of Ontario from January 2016 through December 2018 along with the characteristics of these drivers and some of the circumstances of the crash in which they were involved. Methods Toxicological tests were performed on blood samples obtained from 921 driver fatalities for whom postmortem blood samples were submitted to the Center of Forensic Sciences for analysis. The results were coded into a database along with basic demographic and crash characteristics and examined for prominent characteristics and patterns. Results Overall, among the 921 cases examined, 495 (53.7%) tested positive for alcohol, cannabis (tetrahydrocannabinol or THC), or another psychoactive drug. The number of cases that tested positive for THC (251) exceeded the number of cases that tested positive for alcohol (241) as well as the number that tested positive for a drug other than THC (235). In 38% of positive cases, more than one substance was detected. Alcohol and THC were most commonly detected among males; females most frequently tested positive for a drug other than THC, notably medications with depressant effects. Alcohol-involved driver fatalities were most common on weekends and most likely involved single vehicle crashes. Driver fatalities that tested positive for THC or another drug were more evenly distributed throughout the week and were more likely to have been in multi-vehicle crashes. Conclusions The present study highlights the use of cannabis and other drugs by drivers. The patterns of crashes and the characteristics of drivers involved indicate that the characteristics of driver fatalities involving cannabis and/or other drug use differ from those of alcohol and require new, innovative approaches targeting high-risk times, groups and behaviors. Continued monitoring of the toxicological findings from blood samples obtained from drivers killed in motor vehicle crashes will be a key element in efforts to reduce the impact of drug use by drivers on road safety.
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The case-control design is very suitable when dealing with rare diseases and when many factors for the disease under study need to be evaluated, as is the case in determining the risk of driving under the influence of drugs. However, the methodology is hard to implement and there are many sources of potential bias that could affect the validity of the study results. Case-control studies are therefore not commonly used as a method to assess the risk of driving under the influence of psychoactive substances other than alcohol. The few studies that have been conducted vary in study design, which makes it very hard to compare their outcomes. In 2006 a consensus meeting was organised by the International Council on Alcohol, Drugs and Traffic Safety (ICADTS) to develop standards for future research. These recommendations for standardized research include legal/ethical issues, subject and study design issues, and core data parameters.
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Meta-analysis collects and synthesizes results from individual studies to estimate an overall effect size. If published studies are chosen, say through a literature review, then an inherent selection bias may arise, because, for example, studies may tend to be published more readily if they are statistically significant, or deemed to be more “interesting” in terms of the impact of their outcomes. We develop a simple rank-based data augmentation technique, formalizing the use of funnel plots, to estimate and adjust for the numbers and outcomes of missing studies. Several nonparametric estimators are proposed for the number of missing studies, and their properties are developed analytically and through simulations. We apply the method to simulated and epidemiological datasets and show that it is both effective and consistent with other criteria in the literature.
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Objective: The purpose of this study was to determine the relationship between blood benzodiazepine concentration and crash risk. Methods: Blood samples from 2500 injured drivers were analyzed for benzodiazepines and the relationship between concentration and crash risk was assessed using culpability analysis. Benzodiazepine concentrations were expressed as a proportion of the peak concentration of the drug in blood or plasma for a standard therapeutic dose of the drug. Results: There were 68 drivers (2.7%) who tested positive for at least one benzodiazepine. Of these, 16 (23.5%) also tested positive for alcohol. Drivers who tested positive for benzodiazepines, either alone or in combination with alcohol, had a higher culpability rate than drug-free drivers. There was a significant linear relationship between benzodiazepine concentration and culpability for drivers who tested positive for benzodiazepines alone. Conclusion: The results here provide clear evidence of increased culpability associated with benzodiazepine use, which was marked at higher concentrations.
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To determine whether the acute consumption of cannabis (cannabinoids) by drivers increases the risk of a motor vehicle collision. Systematic review of observational studies, with meta-analysis. 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. We selected nine studies in the review and meta-analysis. Driving under the influence of cannabis was associated with a significantly increased risk of motor vehicle collisions compared with unimpaired driving (odds ratio 1.92 (95% confidence interval 1.35 to 2.73); P=0.0003); we noted heterogeneity among the individual study effects (I(2)=81). Collision risk estimates were higher in case-control studies (2.79 (1.23 to 6.33); P=0.01) and studies of fatal collisions (2.10 (1.31 to 3.36); P=0.002) than in culpability studies (1.65 (1.11 to 2.46); P=0.07) and studies of non-fatal collisions (1.74 (0.88 to 3.46); P=0.11). Acute cannabis consumption is associated with an increased risk of a motor vehicle crash, especially for fatal collisions. This information could be used as the basis for campaigns against drug impaired driving, developing regional or national policies to control acute drug use while driving, and raising public awareness.
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It is known that many image enhancement methods have a tradeoff between noise suppression and edge enhancement. In this paper, we propose a new technique for image enhancement filtering and explain it in human visual perception theory. It combines kernel regression and local homogeneity and evaluates the restoration performance of smoothing method. First, image is filtered in kernel regression. Then image local homogeneity computation is introduced which offers adaptive selection about further smoothing. The overall effect of this algorithm is effective about noise reduction and edge enhancement. Experiment results show that this algorithm has better performance in image edge enhancement, contrast enhancement, and noise suppression.
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The aim of the study was to investigate the association between the use of benzodiazepine or benzodiazepine-like hypnotics and the risk of road traffic accidents. Data from three French national databases were matched: the health-care insurance database, police reports, and the police database of injury-related traffic accidents. A total of 72,685 drivers involved in injury-related road traffic accidents in France, from 2005 to 2008, were included in the study. The risk of being responsible for a traffic accident was higher in users of benzodiazepine hypnotics (odds ratio (OR) = 1.39 (1.08-1.79)) and in the 155 drivers to whom a dosage of more than one pill of zolpidem a day had been dispensed during the 5 months before the collision (OR = 2.46 (1.70-3.56)). No association was found between the use of zopiclone and risk of traffic accidents. Although this study did not find any association between the use of zolpidem as recommended and causation of traffic accidents, the potential risk related to possible abuse of the drug and risky driving behaviors should be further investigated. The results related to benzodiazepine hypnotics are consistent with those of previous studies.
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Many individuals in the community are prescribed psychoactive drugs with sedative effects. These drugs may affect their daily functions, of which automobile driving is a major component. To examine the association of three classes of commonly used psychoactive drugs (viz. benzodiazepines and newer non-benzodiazepine hypnotics, antidepressants and opioids) with (i) the risk of traffic accidents (as indexed by epidemiological indicators of risk); and (ii) driving performance (as indexed by experimental measures of driving performance). A literature search for material published in the English language between January 1966 and January 2010 in PubMed and EMBASE databases was combined with a search for other relevant material referenced in the retrieved articles. Retrieved articles were systematically reviewed, carrying out meta-analyses where possible. Twenty-one epidemiological studies (13 case-control and 8 cohort studies) fulfilled the inclusion criteria by estimating the accident risk associated with drug exposure (ascertained by blood/urine analysis or prescription records). Sixty-nine experimental studies fulfilled the inclusion criteria by testing actual or simulated driving performance after administering a single dose or multiple doses. Two meta-analyses showed that benzodiazepines are associated with a 60% (for case-control studies: pooled odds ratio [OR] 1.59; 95% CI 1.10, 2.31) to 80% (for cohort studies: pooled incidence rate ratio 1.81; 95% CI 1.35, 2.43) increase in the risk of traffic accidents and a 40% (pooled OR 1.41; 95% CI 1.03, 1.94) increase in 'accident responsibility'. Co-ingestion of benzodiazepines and alcohol was associated with a 7.7-fold increase in the accident risk (pooled OR 7.69; 95% CI 4.33, 13.65). Subgroup analysis of case-control studies showed a lower benzodiazepine-associated accident risk in elderly (>65 years of age) drivers (pooled OR 1.13; 95% CI 0.97, 1.31) than in drivers <65 years of age (pooled OR 2.21; 95% CI 1.31, 3.73), a result consistent with age-stratified risk differences reported in cohort studies. Anxiolytics, taken in single or multiple doses during the daytime, impaired driving performance independent of their half-lives. With hypnotics, converging evidence from experimental and epidemiological studies indicates that diazepam, flurazepam, flunitrazepam, nitrazepam and the short half-life non-benzodiazepine hypnotic zopiclone significantly impair driving, at least during the first 2-4 weeks of treatment. The accident risk was higher in the elderly (>65 years of age) who use tricyclic antidepressants (TCAs); however, the evidence for an association of antidepressants with accident risk in younger drivers was equivocal. Sedative but not non-sedative antidepressants were found to cause short-term impairment of several measures of driving performance. Limited epidemiological research reported that opioids may be associated with increased accident risk in the first few weeks of treatment. Benzodiazepine use was associated with a significant increase in the risk of traffic accidents and responsibility of drivers for accidents. The association was more pronounced in the younger drivers. The accident risk was markedly increased by co-ingestion of alcohol. Driving impairment was generally related to plasma half-lives of hypnotics, but with notable exceptions. Anxiolytics, with daytime dosing, impaired driving independent of their half-lives. TCAs appeared to be associated with increased accident risk, at least in the elderly, and caused short-term impairment in driving performance. Opioid users may be at a higher risk of traffic accidents; however, experimental evidence is limited on their effects on driving.
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In recent decades, increased attention has been focused on the impact of disabilities and medicinal drug use on road safety. The aim of our study was to investigate the association between prescription medicines and the risk of road traffic crashes, and estimate the attributable fraction. We extracted and matched data from three French nationwide databases: the national health care insurance database, police reports, and the national police database of injurious crashes. Drivers identified by their national health care number involved in an injurious crash in France, between July 2005 and May 2008, were included in the study. Medicines were grouped according to the four risk levels of the French classification system (from 0 [no risk] to 3 [high risk]). We included 72,685 drivers involved in injurious crashes. Users of level 2 (odds ratio [OR]  = 1.31 [1.24-1.40]) and level 3 (OR  = 1.25 [1.12-1.40]) prescription medicines were at higher risk of being responsible for a crash. The association remained after adjustment for the presence of a long-term chronic disease. The fraction of road traffic crashes attributable to levels 2 and 3 medications was 3.3% [2.7%-3.9%]. A within-person case-crossover analysis showed that drivers were more likely to be exposed to level 3 medications on the crash day than on a control day, 30 days earlier (OR  = 1.15 [1.05-1.27]). The use of prescription medicines is associated with a substantial number of road traffic crashes in France. In light of the results, warning messages appear to be relevant for level 2 and 3 medications and questionable for level 1 medications. A follow-up study is needed to evaluate the impact of the warning labeling system on road traffic crash prevention.
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Several epidemiological and experimental studies have found a positive association between the risk of motor vehicle accidents (MVAs) and use of zopiclone and benzodiazepines. There is, however, little evidence of any risk of MVA attributable to the use of zolpidem 1 day before such accidents. We attempted to determine whether the use of zolpidem 1 day before is associated with an increased risk of an MVA. Using a 1-million-person randomly sampled cohort from the Taiwan National Health Insurance reimbursement database, 12 929 subjects were identified as having been hospitalized between 1998 and 2004 due to an MVA. Using a case-crossover design, we selected the day before an MVA as the case period for each subject, and the 91st, 182nd, and 273rd days before the case period as 3 retrospective control periods. Conditional logistical regression models were constructed to calculate the odds ratio (OR) of having an MVA and the exposure of zolpidem 1 day before. We calculated doses of benzodiazepines, zopiclone, and zolpidem based on their defined daily dose. The adjusted OR for involvement in an MVA after taking 1 defined daily dose of zolpidem was 1.74 (95% confidence interval: 1.25-2.43). There were also positive effects for different washout periods and cumulative doses at 7, 14, 21, and 28 days before the occurrence of an MVA. Use of zolpidem 1 day before might be associated with an increased risk of MVA. Thus, precautionary warnings should be provided when prescribing zolpidem.
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Chapter
IntroductionHistory and DevelopmentModelling Publication BiasAdjusting for Publication BiasFormal Tests for Publication BiasApplying ‘Trim and Fill’ in PracticeLimitations and Future ResearchExamplesConclusions References
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PurposeContradictory results were published from two studies in the late 1990s about the effects of long half-life benzodiazepine use on the risk of motor vehicle crashes (MVCs) in the elderly. The use of different study designs could explain the differences observed in these studies.Methods The results of an unmatched case-control study were compared to those of a case-crossover study using the same prescription claims database to determine whether the current use of benzodiazepines increased the risk of MVCs.ResultsThere were 5579 cases and 12 911 controls identified between the years 1990 and 1993 in the province of Quebec, Canada. The case-control approach demonstrated an increased rate of injurious MVC associated with the current use of long-acting benzodiazepines [odds ratio (OR) 1.45; 95% confidence interval (CI): 1.12–1.88]. The case-crossover approach applied to all cases did not show any association [OR 0.99; 95%CI: 0.83–1.19]. However, among the cases restricted to subjects with four or less prescriptions filled in the previous year, corresponding more to transient exposures, the OR was elevated [OR 1.53; 95%CI: 1.08–2.16].Conclusions Differences in study design and analysis may explain some of the discrepancies in previous results. Both study designs provide evidence that long-acting benzodiazepines appear to be associated with an increased risk of MVC. Copyright © 2007 John Wiley & Sons, Ltd.
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Anonymous random digit dialing telephone surveys of nearly 6000 16–19 year old respondents were conducted in Massachusetts and Upstate New York in 1979–1981. These surveys explored frequency of driving after using marijuana, driving after drinking, respondent accident involvement in the year prior to the interview, and a variety of other respondent characteristics. Frequency of driving after using marijuana and after drinking were each associated with greater accident involvement. To isolate the accident risk of driving after marijuana use, respondents who drove after drinking were excluded from a logistic regression analysis. This analysis also controlled for the distance respondents drove and several respondent demographic characteristics. Compared to respondents who did not drive after marijuana use, teenageers who drove after smoking marijuana on at least 6 occasions per month were 2.4 times more likely to be involved in traffic accidents. Those who drove after marijuana use on at least 15 occasions per month were 2.9 times more likely to have an accident.
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The role of Delta(9)-tetrahydrocannabinol (THC) in driver impairment and motor vehicle crashes has traditionally been established in experimental and epidemiological studies. Experimental studies have repeatedly shown that THC impairs cognition, psychomotor function and actual driving performance in a dose related manner. The degree of performance impairment observed in experimental studies after doses up to 300 microg/kg THC were equivalent to the impairing effect of an alcohol dose producing a blood alcohol concentration (BAC) >/=0.05 g/dl, the legal limit for driving under the influence in most European countries. Higher doses of THC, i.e. >300 microg/kg THC have not been systematically studied but can be predicted to produce even larger impairment. Detrimental effects of THC were more prominent in certain driving tasks than others. Highly automated behaviors, such as road tracking control, were more affected by THC as compared to more complex driving tasks requiring conscious control. Epidemiological findings on the role of THC in vehicle crashes have sometimes contrasted findings from experimental research. Case-control studies generally confirmed experimental data, but culpability surveys showed little evidence that crashed drivers who only used cannabis are more likely to cause accidents than drug free drivers. However, most culpability surveys have established cannabis use among crashed drivers by determining the presence of an inactive metabolite of THC in blood or urine that can be detected for days after smoking and can only be taken as evidence for past use of cannabis. Surveys that established recent use of cannabis by directly measuring THC in blood showed that THC positives, particularly at higher doses, are about three to seven times more likely to be responsible for their crash as compared to drivers that had not used drugs or alcohol. Together these epidemiological data suggests that recent use of cannabis may increase crash risk, whereas past use of cannabis does not. Experimental and epidemiological research provided similar findings concerning the combined use of THC and alcohol in traffic. Combined use of THC and alcohol produced severe impairment of cognitive, psychomotor, and actual driving performance in experimental studies and sharply increased the crash risk in epidemiological analyses.
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Replies to a question on the medication usage of a large population of drivers subjected to evidential breath analysis were examined, and related to the age, sex and BAC of the driver, and to whether or not he was breath analysed after a crash. In an initial analysis, medications were classified into 13 major groups (including a drug negative, or control, group) and a log-linear analysis carried out on the cross-tabulation of age (five categories) by BAC (five categories) by drug (13 categories) by crash/no crash. (Analysis was restricted to males, since the number of females was very small). A reduced model was obtained, and the ratio of the odds of a crash in each drug group to the odds of a crash in the appropriate drug negative group computed. In a second stage of analysis, the analgesic and CNS depressant categories were expanded to individual agents, and odds ratios again computed. A number of individual drugs and drug groups were associated with an elevated crash risk. These included CNS depressants (diazepam, oxazepam, antidepressants), analgesics (d-propoxyphene) and drugs for the treatment of diabetes. In general, effects were most marked at low BAC's.
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Examined the differences in risk of injurious traffic accidents after benzodiazepine (BZD) use in older adults (aged 60+ yrs) compared with those younger. Also the differences in effect of short acting and long acting BZD and, more tentatively, differences in effect of first-time and long-term will be considered. The study design is an epidemiologic cohort study for which data was received from 225,796 persons above 20 with a first BZD prescription and 97,862 controls from the Saskatchewan Health Data Bases. New users increased their risk of injurious traffic accidents within the first 4 wks of the BZD prescription. For individual BZD, flurazepam showed the largest increase in risk; stratified for age the odds ratio (OR) was 6.1 for the under 60 and 3.4 for the over 60 age groups. The number of traffic accidents in the repeat use population was very small, but they hint at the possibility that repeat users have a lower risk than new users. Results need to be confirmed and the recommendations are that further studies be done to ferret out relations among the various potential influences of age, type of BZD, and length of use. (PsycINFO Database Record (c) 2006 APA, all rights reserved) DOI: doi:10.1002/(SICI)1099-1077(1998110)13:2+ 3.3.CO;2-F
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A large number of studies have tried to assess how various aspects of driver health influence driver involvement in accidents. The objective of this paper is to provide a framework for a critical assessment of the quality these studies from a methodological point of view. Examples are given of how various sources of bias and confounding can produce study findings that are highly misleading. Ten potential sources of error and bias in epidemiological studies of the contribution of driver health impairments to road accidents are discussed: (1) Poor description of the medical conditions whose effects are studied (measurement error). (2) Inadequate control for the effects of exposure on accident rate. (3) Sampling endogeneity with respect to assessment for fitness to drive (outcome-based sampling; self-selection bias). (4) Combined exposure to several risk factors. (5) Poor control for potentially confounding factors. (6) Failure to specify potentially moderating factors (interaction effects). (7) Failure to consider a severity gradient with respect to the effect of health impairments. (8) Failure to specify the compliance of drivers with medical treatments or treatment effectiveness. (9) No data on the population prevalence of various health conditions. (10) The use of multiple study approaches and methods making the comparison and synthesis of findings difficult. Examples are given of how all these items may influence the findings of a single study or make synthesising findings from multiple studies difficult. A checklist for assessing study quality is provided.
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A case-control study was conducted on 204 drivers fatally injured in road traffic accidents in south-eastern Norway during the period 2003-2008. Cases from single vehicle accidents (N = 68) were assessed separately. As controls, 10540 drivers selected in a roadside survey in the same geographical area during 2005-2006 were used. Blood samples were collected from the cases and oral fluid (saliva) samples from the controls. Samples were analysed for alcohol, amphetamines, cannabis, cocaine, opioid analgesics, hypnotics, sedatives and a muscle relaxant; altogether 22 psychoactive substances. Equivalent cutoff concentrations for blood and oral fluid were used. The risk for fatal injury in a road traffic accident was estimated using logistic regression adjusting for gender, age, season of the year, and time of the week. The odds for involvement in fatal road traffic accidents for different substances or combination of substances were in increasing order: single drug < multiple drugs < alcohol only < alcohol+drugs. For single substance use: medicinal drug or THC < amphetamine/methamphetamine < alcohol. For most substances, higher ORs were found when studying drivers involved in single vehicle accidents than for those involved in multiple vehicle accidents, but confidence intervals were wider.