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

Prevalence of Substance Abuse Among Trauma Patients in Rural West Virginia

BACKGROUND

 Substance abuse poses considerable clinical, economic, and social challenges. West Virginia is hailed as the epicenter of the substance abuse in the United States, the prevalence and pattern of different trauma mechanisms in a rural context or in patients with different forms of substance abuse remain unclear.

OBJECTIVE

 We performed the following analysis to understand the prevalence of substance abuse in patients with different trauma mechanisms in the rural setting with high substance abuse in the West Virginia.

METHODS

 We performed a cross-sectional retrospective analysis of adult trauma patients (motor vehicle, fall, assault, firearm suicide, brawl/rape and machinery) hospitalized in two tertiary care hospitals in West Virginia between 2006 and 2016. We identified all patients who had a urine drug screen (UDS) test and extracted the data related to the substance and trauma.

RESULTS

 Among 8734 patients screened using UDS, 5940 (68.1%) patients were tested positive for the substance. Opiates, alcohol, benzodiazepines, and cannabis were the four most common substances identified in trauma victims. In all instances, the prescribed drug was less than 20%. Fatal outcome was observed in 366 patients in the sample, with 44% (n=162) testing positive for UDS, 12% (n=45) testing positive for only alcohol, and 15% (n=56) testing positive for both alcohol and UDS. Regarding the trauma mechanism, the motor vehicle accident (MVA) was the most prominent with a clear association of substance abuse with fatal outcome.

CONCLUSION

 The most prevalent trauma mechanism was a MVA, with a strong link between drug usage and mortality. Due to the high incidence of positive substance abuse screens, UDS tests may need to be more widely implemented in trauma in the West Virginia region. The findings of this study might help in establishing regional or national policies to reduce acute substance abuse.

The prevalence of alcohol use and risky driving practises among individuals who consume sedatives nonmedically: findings from the NESARC-III

Background: Worldwide, 1.3 million people die because of a road traffic collision each year, with over half (57.7%) of such deaths in the United States involving a psychoactive substance. The prevalence of drink-drivers is slowly declining; however, the number of drivers under the influence of other drugs, such as sedatives, continues to rise.Objectives: This study aimed to examine alcohol use and risky driving practices among individuals who consume sedatives nonmedically.Methods: A total of 36,309 US adults (48.1% male) who participated in wave 3 (2012) of the National Epidemiologic Survey on Alcohol and Related Conditions were included for analysis.Results: Overall, 827 respondents reported past-year nonmedical sedative use. Almost two-third (64.9%) of these individuals exceeded recommended drinking guidelines and 42.5% met the criteria for a past-year DSM-5 alcohol use disorder. When controlling for demographic, lifestyle, and health factors, they were 1.84 times as likely to drink-drive (95% confidence interval = 1.46-2.33, p < .001) compared to those not using sedatives or using them as prescribed. Among those who reported both drink-driving and driving under the influence of sedatives in the last 12 months, 68.1% met the criteria for a past-year DSM-5 sedative use disorder.Conclusion: Several driving outcomes relevant to road safety, such as driving under the influence of alcohol or sedatives, are impacted by sedative consumption. Given that individuals who consume sedatives nonmedically may be unaware or misperceive the impacts of substance use on safe driving, interventions to reduce such behavior should be targeted among this high-risk group.

The role of alcohol and drug intoxication in fatal drowning and other deaths that occur on the Australian coast

INTRODUCTION

Alcohol and drug (illicit or prescription) intoxication impairs motor skills, coordination, decision making abilities, hazard perception, and is known to increase the risk of death in coastal environments. Prior coastal safety research has focused largely on the impact of alcohol on drowning, with less research on the influence of drugs and leaving a significant number of other non-drowning fatalities largely excluded, despite being preventable with mitigation of injuries or medical factors.

METHOD

This retrospective cross-sectional study explored the impact of alcohol and drugs on unintentional Australian drowning deaths and other coastal fatalities over a 16-year period to identify higher-risk populations and coastal activity groups for which alcohol/drug use is increased.

RESULTS

It was found that alcohol, benzodiazepines/sedatives, and amphetamine usage was prevalent in coastal deaths. Of the 2,884 coastal deaths, 80.6% of decedents had known toxicological data. Alcohol and/or drug intoxication contributed to 23% of coastal drowning deaths and 19% of fatalities. For drowning and other fatalities combined, 8.7% were due to alcohol, 8.7% due to drugs, and 4.1% due to both alcohol and drugs. Australian-born decedents were more likely to involve alcohol (RR = 1.7, 95%CI = 1.26-2.3, p &lt; 0.001), drugs (RR = 2.62, 95%CI = 1.85-3.7, p &lt; 0.001), or both alcohol and drugs (RR = 4.43, 95%CI = 2.51-7.82, p &lt; 0.001) with an increased risk identified in Indigenous Australian populations (RR = 2.17, 95%CI = 1.12-4.24, p = 0.04). The impact of alcohol and drug intoxication varied by activity, with Personal Watercraft users more likely to die due to alcohol intoxication (RR = 2.67, 95%CI = 1.23-5.78, p = 0.035), while scuba divers (RR = 0, p &lt; 0.001), snorkelers (RR = 0.14, 95%CI = 0.036-0.57, p &lt; 0.001), and rock fishers (RR = 0.46, 95%CI = 0.22-0.96, p = 0.03) were less likely. Recreational jumping and fall-related coastal deaths were more likely to involve alcohol and alcohol/drugs combined.

PRACTICAL APPLICATIONS

This study identifies factors to further investigate or target with prevention strategies to decrease the holistic burden of mortality due to alcohol and/or drug usage on the Australian coast.

Cannabinoids, Insomnia, and Other Sleep Disorders

Sleep disturbances are often cited as a primary reason for medicinal cannabis use, and there is increasing clinical interest in the therapeutic potential of cannabinoids in treating sleep disorders. Burgeoning evidence suggests a role of the endocannabinoid system in regulating the circadian sleep-wake cycle, highlighting a potential avenue for developing novel therapeutics. Despite widespread use of cannabis products as sleep aids globally, robustly designed studies verifying efficacy in sleep-disordered populations are limited. Although some study outcomes have suggested cannabinoid utility in insomnia disorder and sleep apnea, most studies to date are limited by small sample sizes, lack of rigorously controlled study designs, and high risk of bias. This critical review summarizes the current evidence for the use of cannabinoids as a treatment for sleep disorders and provides an overview of endocannabinoid modulation of sleep-wake cycles, as well as the sleep-modulating effects of plant-derived cannabinoids such as delta-9-tetrahydrocannbinol, cannabidiol, and cannabinol. The review also discusses practical considerations for clinicians regarding cannabinoid formulations, routes of administration, respiratory concerns, dosing, potential side effects, drug interactions, and effects relevant to driving, tolerance, and withdrawal. Although current interest in, and uptake of, medicinal cannabis use for sleep disorders may have surpassed the evidence base, there is a strong rationale for continued investigation into the therapeutic potential of cannabinoids.

Versatile, but not focused, traffic offenders are more likely to be at fault for a fatal crash

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.

Prevalence and concentrations of sedative-hypnotic drugs in blood of drivers involved in road traffic crashes in the Padova region of Italy - not so easy to interpret

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 4066 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 Wales 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. Besides the concentrations of drugs in blood, 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.

The who, what and when of drug driving in Queensland: Analysing the results of roadside drug testing, 2015-2020

Roadside Drug Testing (RDT) is the primary strategy utilised in Australia to detect and deter drug driving. RDT operations have been expanding and evolving in Queensland since their introduction in 2007, with the number of tests increasing by 5.63 times between 2009 and 2019. The objective of this paper was to explore trends and characteristics of the 60,551 positive results detected in Queensland's RDT program (from January 2015 to June 2020), which focuses on the detection of Delta-9-tetrahydrocannabinol (THC), Methylenedioxymethylamphetamine (MDMA) and methamphetamine (MA). The analysis indicated that (over the entire testing period) MA was the most common drug detected in isolation (39.4%), followed by THC (34%) and the combination of MA and THC (21.9%). When considering detections with two or more drugs, MA was present in 64% of detections, THC in 59% and MDMA in 1.8%. THC was most commonly detected among younger drivers (e.g., aged 16 to 24), while MA was most commonly detected with drivers aged 25 and 59 years. Analysis of sociodemographic and contextual factors revealed that positive roadside tests were most commonly associated with males who had consumed methamphetamines, aged between 30 and 39 who were driving a car on a Friday or Saturday between 2:00 pm and 6:00 pm. The findings provide some indication as to the extent of drug driving within Queensland (and growing use of MA) and have clear implications for enforcement activities, not least, directing sufficient resources to address the burgeoning problem.

An Update to Aircrew Grounding Periods After Ketamine Use

INTRODUCTION: Ketamine is a rapidly acting general anesthetic which is globally used in surgical analgesia, as well as in the management of pain. It is also used as a recreational drug. Because of its widespread use in surgical settings, the use of this drug presents an aeromedical problemin addition, of course, to the underlying condition for which it has been used. The literature around the mechanisms and side effects of ketamine is reasonably mature, and it is possible to make fairly dependable risk management decisions about return to flying based on the information available. Accordingly, following ketamine use it is recommended that aviators be grounded for 48 h following Aviation Medical Examiner review. If review is unavailable, the aviator should be grounded for 1 wk to allow sufficient time to identify the existence of prolonged side effects, such as psychomimetic effects or cognitive changes.Boyd NL, Navathe PD. An update to aircrew grounding periods after ketamine use. Aerosp Med Hum Perform. 2021; 92(8):670-675.

Screening major trauma patients for prevalence of illicit drugs

INTRODUCTION

Australasian emergency departments (ED) routinely test patient alcohol levels following major trauma, but assessment for illicit drugs is uncommon.

METHODS

A prospective cross-sectional study of major motor-vehicle-related trauma patients attending both adult major trauma centres in Victoria, Australia. All eligible patients had point-of-care saliva testing to determine the prevalence of common illicit drugs.

RESULTS

Over 12 months, 1411 patients were screened, 36 refused (2.6%) and 63 were excluded. Of the final 1312 cases included, 173 (13.2%; 95% confidence interval 11.5, 15.1) tested positive to at least one illicit substance, with 133 (76.9%; 69.7, 82.8) positive for meth/amphetamines. One in five had more than one illicit substance detected. Patients testing positive were most frequently in motor vehicles (91.9% vs. 85.6%) and least frequently cyclists (2.3% vs. 4.2%) or pedestrians (5.2% vs. 10.3%), compared to those testing negative. They were younger (mean age 35.4 vs. 43.1 years), more likely to arrive overnight (27.2% vs. 12.1%) or after single vehicle crashes (54.3% vs. 42.3%). Although the initial disposition from ED did not differ, those testing positive were more likely to re-present within 28 days (13.9% vs. 5.4%).

DISCUSSION AND CONCLUSIONS

A high prevalence of potentially illicit substances among patients presenting with suspected major trauma supports the need for urgent preventive strategies. The low rate of patient refusal and large numbers screened by ED staff suggests that point-of care testing for illicit substances in major trauma is acceptable and feasible. This study and ongoing surveillance may be used to inform driver education strategies.

Roadside Drug Testing Approaches

The purpose of this review is to present an overview of roadside drug testing, driving enforcement, and drunk/drug driving detection around the world. Drunk and drug driving is a severe problem, not only in the UAE, but also around the world. This has important implications for road safety as drunk or drug driving may increase the chances of a driver’s involvement in a road crash when compared to a drug-free driver. Recently, due to increases in drug-impaired drivers’ crash involvement, many mobile roadside drug testing devices have been introduced to the market. These devices use oral fluid, urine or blood matrices. These are on-the-spot tests, which are easy to use and are applied by law enforcement agencies and the public. Law enforcement agencies most commonly use oral fluid to detect the presence of illicit drugs in drivers. This review discusses all the available devices in the market used by the authorities. It also describes the type of drugs widely abused by drivers along with behavioral testing methods. The different types of matrices used for roadside drug testing are also evaluated. Sample collection, storage, and pre-treatment methods are discussed, followed by the confirmatory analysis of positive samples. This article will significantly help law enforcement agencies compare and evaluate all the reliable roadside testing devices and new emerging confirmatory devices available to them in the market. This will help them make an informed decision on which device to adapt to their individual needs.

Current state of hypnotic use disorders: Results of a survey using the Japanese version of Benzodiazepine Dependence Self-Report Questionnaire

Aims

Benzodiazepine receptor agonists (BZ‐RAs) are frequently prescribed to treat insomnia; however, their long‐term use is not recommended. To introduce an appropriate pharmaco‐therapy, the current state and background factors of BZ‐RAs' dependence must be elucidated. In this study, we developed a Japanese version of the Benzodiazepine Dependence Self‐Report Questionnaire (Bendep‐SRQ‐J) and conducted a study of BZ‐RAs' use disorder.

Methods

The Bendep‐SRQ‐J was created with permission from the original developer. Subjects were inpatients and outpatients receiving BZ‐RAs between 2012 and 2013. Clinical data collected were Bendep‐SRQ‐J scores, sleep disorders for which BZ‐RAs were prescribed, physical comorbidities, psychotropic drugs, and lifestyle factors. Logistic analysis was performed to extract factors associated with severe symptoms.

Results

Of the 707 patients prescribed BZ‐RAs, 324 had voluntarily tapered or discontinued their drugs. Logistic analysis showed that the total number of drugs administered in the last 6 months correlated with both worsening of symptoms or conditions. This was more notable among younger patients, and the proportion of patients with severe symptoms or conditions increased with the increasing number of drugs.

Conclusion

Using the Bendep‐SRQ‐J, we elucidated the current state of BZ‐RA dependence. Nearly half of the patients were non‐compliant. The proportion of patients with severe symptoms or disease conditions increased with the increase in the number of drugs administered. These findings highlight the need for clinicians to be aware of the likelihood of benzodiazepine dependence, especially in young patients and patients prescribed multiple hypnotics.

Using the Bendep‐SRQ‐J, we elucidated the current state of BZ‐RA dependence. Nearly half of the patients were non‐compliant.

Prescription medication use as a risk factor for motor vehicle collisions: a responsibility study

INTRODUCTION

Previous studies on the effect of prescription medications on MVCs are sparse, not readily applicable to real-world driving and/or subject to strong selection bias. This study examines whether the presence of prescription medication in drivers' blood is associated with being responsible for MVC.

METHODS

This modified case-control study with responsibility analysis compares MVC responsibility rates among drivers with detectable levels of six classes of prescription medications (anticonvulsants, antidepressants, antihistamines, antipsychotics, benzodiazepines, opioids) versus those without. Data were collected between January 2010 and July 2016 from emergency departments in British Columbia, Canada. Collision responsibility was assessed using a validated and automated scoring of police collision reports. Multivariable logistic regression was used to determine OR of responsibility (analysed in 2018-2019).

RESULTS

Unadjusted regression models show a significant association between anticonvulsants (OR 1.92; 95% CI 1.20 to 3.09; p=0.007), antipsychotics (OR 5.00; 95% CI 1.16 to 21.63; p=0.03) and benzodiazepines (OR 2.99; 95% CI 1.56 to 5.75; p=0.001) with collision responsibility. Fully adjusted models show a significant association between benzodiazepines with collision responsibility (aOR 2.29; 95% CI 1.16 to 4.53; p=0.02) after controlling for driver characteristics, blood alcohol and Δ-9-tetrahydrocannabinol concentrations, and the presence of other prescription medications. Antidepressants, antihistamines and opioids exhibited no significant associations.

CONCLUSION

There is a moderate increase in the risk of a responsible collision among drivers with detectable levels of benzodiazepines in blood. Physicians and pharmacists should consider collision risk when prescribing or dispensing benzodiazepines. Public education about benzodiazepine use and driving and change to traffic policy and enforcement measures are warranted.

Factors associated with serious vehicular accidents: A cross-sectional study in hospital emergency rooms

AIMS

Pictograms on medicine boxes warn of potential drug-related driving hazard; we studied their association with serious accidents.

METHODS

Prospective study in emergency departments of the hospitals in Bordeaux and Périgueux (France), of drivers with serious (admitted at least 24 hours) or nonserious vehicular accidents. Minors, passengers, pedestrians or subjects incapable of answering an interview were excluded. Interviews ascertained driver and accident characteristics, use of drugs with or without pictograms, use of alcohol and abuse substances, sleepiness, distractions, and mind wandering at the time of the accident, RESULTS: Between 18 October 2016 and 26 December 2018, 1200 of the 6212 drivers admitted to the hospital emergency rooms, 741 nonserious, 459 serious, were interviewed. Serious accidents were associated with male sex (odds ratio 1.89, 95% confidence interval [1.36-2.64]), age above 60 years (3.64 [2.21-6.00]), driving on local roads (3.34 [2.34-4.76]), driving a motorcycle (3.39 [2.29-5.00]), having drunk alcohol within 6 hours (2.89 [1.85-4.51]) and using a drug with a pictogram during the 24 hours previous to the accident (1.57 [1.06-2.32]). From 207 police reports, 101 drivers were not responsible, and 106 were responsible, associated with age below 40 years, driving in overcast or rainy weather (2.62 [1.29-5.33]), on local roads (3.89 [1.90-7.95]), and use of at least 1 pictogram drug in the previous week (3.12 [1.31-7.41]).

CONCLUSION

The known risks of alcohol and pictogram drugs, of riding motorcycles and using local roads were confirmed. As measured, behavioural sleepiness did not predict accidents.

Risk of 30-day mortality and its association with alcohol concentration level among driver victims of motor vehicle crashes: comparison of population- and hospital-based designs

BACKGROUND

Although blood alcohol concentration (BAC) is undoubtedly associated with increased risk of injury among driver victims involved in motor vehicle crashes (MVCs), some studies noted that high BAC was associated with reduced risk of mortality after injury. In addition, most of the previous studies included only injured patients admitted, which may lead to potential selection bias arising from exclusion of those with minor injury and those who died at the accident scene of MVC.

METHOD

The population-based design included 2586 driver victims with BAC equivalent >0 and 10 307 matched controls (BAC equivalent =0) selected from the Police-reported Traffic Accident Registry from 1 July to 31 December 2016 in Taiwan. The hospital-based design comprised a subset sample, which included 517 driver victims with BAC equivalent >0 and 662 with BAC equivalent =0 hospitalised on the same day the MVCs occurred. Conditional logistic regression models with adjustment for potential confounders were used to estimate the ORs and 95% CIs of 30-day mortality associated with BAC equivalent level.

RESULTS

In the population-based design, a positive dose-gradient relationship was observed between BAC equivalent level and 30-day mortality, with a covariate-adjusted OR of 3.77 (95% CI 1.84 to 7.72), 6.19 (95% CI 3.13 to 12.26) and 7.75 (95% CI 4.51 to 13.32) for low, moderate and high BAC equivalent levels, respectively. By contrast, the hospital-based design revealed no significant association between 30-day mortality and alcohol concentration regardless of the BAC equivalent level.

CONCLUSION

The association between BAC equivalent level and short-term mortality could have been overlooked in hospital-based studies that excluded MVC-related deaths outside hospital settings.

Cannabis-impaired driving and Canadian youth

Acute cannabis use results in inattention, delayed information processing, impaired coordination, and slowed reaction time. Driving simulator studies and epidemiologic analyses suggest that cannabis use increases motor vehicle crash risk. How much concern should we have regarding cannabis associated motor vehicle collision risks among younger drivers? This article summarizes why young, inexperienced drivers may be at a particularly high risk of crashing after using cannabis. We describe the epidemiology of cannabis use among younger drivers, why combining cannabis with alcohol causes significant impairment and why cannabis edibles may pose a heightened risk to traffic safety. We provide recommendations for clinicians counselling younger drivers about cannabis use and driving.

Odds of culpability associated with use of impairing drugs in injured drivers in Victoria, Australia

Culpability analysis was conducted on 5000 drivers injured as a result of a vehicular collision and in whom comprehensive toxicology testing in blood was conducted. The sample included 1000 drivers for each of 5 years from approximately 5000-6000 drivers injured and taken to hospital in the State of Victoria. Logistic regression was used to investigate differences in the odds of culpability associated with alcohol and drug use and other selected crash attributes using the drug-free driver as the reference group. Adjusted odds ratios were obtained from multivariable logistic regression models in which other potentially explanatory driver and crash attributes were included. Drivers with alcohol present showed large increases in the odds of culpability similar to that seen in other studies investigating associations between blood alcohol concentration and crash risk. Methylamphetamine also showed a large increase in the odds of culpability (OR 19) compared to the reference group at both below and above 0.1 mg/L, whereas those drivers with Δ⁹-tetrahydrocannabinol (THC) present showed only modest increase in odds when all concentrations were assessed (OR 1.9, 95 %CI 1.2-3.1). Benzodiazepines in drivers also gave an increase in odds (3.2, 95 %CI 1.6-6.1), but not other medicinal drugs such as antidepressants, antipsychotics and opioids. Drivers that had combinations of impairing drugs generally gave a large increase in odds, particularly combinations of alcohol with THC or benzodiazepines, and those drivers using both THC and methamphetamine.

Cannabis use as a risk factor for causing motor vehicle crashes: a prospective study

AIM

We conducted a responsibility analysis to determine whether drivers injured in motor vehicle collisions who test positive for Δ-9-tetrahydrocannabinol (THC) or other drugs are more likely to have contributed to the crash than those who test negative.

DESIGN

Prospective case-control study.

SETTING

Trauma centres in British Columbia, Canada.

PARTICIPANTS

Injured drivers who required blood tests for clinical purposes following a motor vehicle collision.

MEASUREMENTS

Excess whole blood remaining after clinical use was obtained and broad-spectrum toxicology testing performed. The analysis quantified alcohol and THC and gave semiquantitative levels of other impairing drugs and medications. Police crash reports were analysed to determine which drivers contributed to the crash (responsible) and which were 'innocently involved' (non-responsible). We used unconditional logistic regression to determine the likelihood (odds ratio: OR) of crash responsibility in drivers with 0 < THC < 2 ng/ml, 2 ng/ml ≤ THC < 5 ng/ml and THC ≥ 5 ng/ml (all versus THC = 0 ng/ml). Risk estimates were adjusted for age, sex and presence of other impairing substances.

FINDINGS

We obtained toxicology results on 3005 injured drivers and police reports on 2318. Alcohol was detected in 14.4% of drivers, THC in 8.3%, other drugs in 8.9% and sedating medications in 19.8%. There was no increased risk of crash responsibility in drivers with THC < 2 ng/ml or 2 ≤ THC < 5 ng/ml. In drivers with THC ≥ 5 ng/ml, the adjusted OR was 1.74 [95% confidence interval (CI) = 0.59-6.36; P = 0.35]. There was significantly increased risk of crash responsibility in drivers with blood alcohol concentration (BAC) ≥ 0.08% (OR = 6.00;95% CI = 3.87-9.75; P < 0.01), other recreational drugs detected (OR = 1.82;95% CI = 1.21-2.80; P < 0.01) or sedating medications detected (OR = 1.45; 95%CI = 1.11-1.91; P < 0.01).

CONCLUSIONS

In this sample of non-fatally injured motor vehicle drivers in British Columbia, Canada, there was no evidence of increased crash risk in drivers with Δ-9-tetrahydrocannabinol < 5 ng/ml and a statistically non-significant increased risk of crash responsibility (odds ratio = 1.74) in drivers with Δ-9-tetrahydrocannabinol ≥ 5 ng/ml.

High levels of alcohol intoxication and strong support for restrictive alcohol policies among music festival visitors

Background

Alcohol intoxication is associated with problems such as violence, injuries, drunk driving and sexual risk-taking, and music festivals are considered a high-risk setting for high levels of alcohol consumption. This study investigates intoxication levels, drinking habits, and opinions on alcohol use and alcohol policies among visitors at one of the largest music festivals in Sweden in 2017.

Methods

A cross-sectional study assessing alcohol intoxication levels was conducted at a music festival (~ 50,000 attendees). Two research teams collected data at the two festival entrances during two nights, from approximately 6:00 pm to 01:30 am. Blood alcohol concentration (BAC) levels were measured using breath analyzers. A face-to-face questionnaire was used to interview attendees about their alcohol use in the past 12 months using the Alcohol Use Disorder Identification Test-Consumption (AUDIT-C), as well as about their personal opinions on alcohol use and alcohol policies (statement). BAC levels were compared between categories of various factors using Mann-Whitney U test and Kruskal-Wallis test. The distributions of BAC, AUDIT-C and statement category across gender was analyzed using Pearson’s Chi-square tests. Associations of BAC levels with different factors were analyzed using Spearman rank correlation and multinomial logistic regression.

Results

A total of 1663 attendees were randomly selected and invited to participate, and 1410 consented (63.7% men, 34.9% women, age 16–64 years). The proportion of drinkers was 81%. Among the drinkers, the median BAC level was 0.082%. Thirty-one percent of the participants had a BAC level above 0.10%. Forty-two percent of the participants reported binge drinking monthly, and 20% said that they binge drank weekly. Sixty-three percent of participants reported risky drinking habits. A self-reported risky alcohol habit increased the risk of a high alcohol intoxication level at the festival. Respondents were supportive of restrictive alcohol policies. Men had significantly higher BAC levels, reported more often risky alcohol habits and were less supportive of restrictive alcohol policies than women.

Conclusions

The results indicate that participants at music festivals in Sweden have high levels of alcohol intoxication and largely support restrictive alcohol policies. Thus, there is both a need and support for the implementation of alcohol prevention strategies at festivals.

A meta-analysis of the crash risk of cannabis-positive drivers in culpability studies-Avoiding interpretational bias

BACKGROUND

Culpability studies, a common study design in the cannabis crash risk literature, typically report odds-ratios (OR) indicating the raised risks of a culpable accident. This parameter is of unclear policy relevance, and is frequently misinterpreted as an estimate of the increased crash risk, a practice that introduces a substantial "interpretational bias".

METHODS

A Bayesian statistical model for culpability study counts is developed to provide inference for both culpable and total crash risks, with a hierarchical effect specification to allow for meta-analysis across studies with potentially heterogeneous risk parameter values. The model is assessed in a bootstrap study and applied to data from 13 published culpability studies.

RESULTS

The model outperforms the culpability OR in bootstrap analyses. Used on actual study data, the average increase in crash risk is estimated at 1.28 (1.16-1.40). The pooled increased risk of a culpable crash is estimated as 1.42 (95% credibility interval 1.11-1.75), which is similar to pooled estimates using traditional ORs (1.46, 95% CI: 1.24-1.72). The attributable risk fraction of cannabis impaired driving is estimated to lie below 2% for all but two of the included studies.

CONCLUSIONS

Culpability ORs exaggerate risk increases and parameter uncertainty when misinterpreted as total crash ORs. The increased crash risk associated with THC-positive drivers in culpability studies is low.

Driving under the influence of drugs: Prevalence in road traffic accidents in Italy and considerations on per se limits legislation

OBJECTIVE

The objective of this study was to present the prevalence and concentrations of drugs in blood samples of drivers involved in road traffic accidents (RTAs) and to discuss the effects of adopting different concentration cutoff values proposed or applied in other European countries on the number of driving under the influence of drugs (DUID) offenses.

METHODS

Blood samples from drivers involved in RTAs in Padova province from 2014 to 2017 were analyzed for the presence of alcohol and drugs. The prevalence of positive subjects was reported for each substance adopting the limits of quantification (LOQs) of our laboratory and the concentration cutoff values proposed and/or used in other European countries. The reduction of cases of driving under the influence of illicit drugs in applying different cutoffs was calculated.

RESULTS

Four thousand four hundred forty-three blood samples were analyzed: 23.7% were positive for alcohol and 19.9% for psychoactive drugs, with prevalences of polydrug and alcohol-drug abuse of 4.5 and 6%, respectively. The most frequently detected drugs were cannabinoids (9.7%) and cocaine (7.2%), followed by benzodiazepines (4.1%), opiates (1.9%), and other opioids (1.7%). Barbiturates, amphetamines, and ketamine were identified in a much smaller number of cases. The overall decrease in DUID cases when adopting different cutoffs with respect to cases above the LOQs was between 8 and 84%. The adoption of high LOQs such as those used in the European Union's research project on Driving Under the Influence of Drugs, Alcohol and Medicines (DRUID) decreases the hypothetical number of DUID offenses by a quarter, and per se limits proposed as broadly equivalent to a blood alcohol concentration (BAC) between 0.2 and 0.8 g/L dramatically reduce the cases of DUID (cocaine -81%, cannabis -79%, opioids -97%, opiates -96%, and amphetamines -77%); no ketamine-positive samples were above the cutoff.

CONCLUSIONS

The implementation of high analytical limits or per se limits based on impairing concentrations in the Italian legislation could result in the prosecution of a much lower number of drugged drivers involved in RTAs, with a decrease from 25% to more than 80% depending on the limits.

Occupational health and safety of road haulage company employees

Background:

This paper follows up on a project that was launched in 2008 and contributed to the development of the new Italian Society of Occupational Medicine (SIML) guidelines for the road haulage industry.

Objective:

To reach a better understanding of occupational illness amongst truck drivers, in order to define appropriate health monitoring protocols and promote a healthy life-style.

Methods:

We assessed 673 male drivers (mean age 43.85 years, SD 9.56; mean working seniority 27.28 years, SD 10.59), employed by 46 different companies. The drivers, who were gradually recruited in the study over the years, had a maximum of 8 re-assessments each, for a total of 2608 examinations. We applied a survey protocol consisting in a medical examination, questionnaires for the most common risks and instrumental and laboratory tests in compliance with SIML guidelines.

Results:

We identified a total of 44 work-related diseases: 22 cases of noise-induced hearing loss (NIHL) and 22 cases of lumbar degenerative disc disease. As regards metabolic disorders, we observed 28 cases of diabetes mellitus, in most cases (71.4%) as a first diagnosis or under poor therapeutic control. We observed poorly-controlled hypertension in 103 drivers, the majority of whom (54%) were diagnosed for the first time. Over 30% of the workers in our study were obese and approximately 40% were tobacco smokers. We identified just 9 individuals (1.3%) with a positive toxicological screening for use of recreational drugs. Our data confirm a high prevalence of occupational illness amongst truck drivers. Cardiovascular and metabolic conditions require close monitoring.

The Association of Unfavorable Traffic Events and Cannabis Usage: A Meta-Analysis

Background: In the last years were published many epidemiological articles aiming to link driving under the influence of cannabis (DUIC) with the risk of various unfavorable traffic events (UTEs), with sometimes contradictory results.

Aim: The primary objective of this study was to analyze whether there is a significant association between DUIC and UTEs.

Materials and Methods: We used two meta-analytical methods to assess the statistical significance of the effect size: random-effects model and inverse variance heterogeneity model.

Results: Twenty-four studies were included in the meta-analysis. We obtained significant increases in the effect size for DUIC tested through blood analysis, with an odds ratio (OR) of 1.97 and a confidence interval (CI) between 1.35 and 2.87; death as an outcome, with an OR of 1.56 and a CI between 1.16 and 2.09; and case–control as the type of study, with an OR of 1.99 and a CI between 1.05 and 3.80. Publication bias was very high.

Conclusion: Our analysis suggests that the overall effect size for DUIC on UTEs is not statistically significant, but there are significant differences obtained through subgroup analysis. This result might be caused by either methodological flaws (which are often encountered in articles on this topic), the indiscriminate employment of the term “cannabis use,” or an actual absence of an adverse effect. When a driver is found, in traffic, with a positive reaction suggesting cannabis use, the result should be corroborated by either objective data regarding marijuana usage (like blood analyses, with clear cut-off values), or a clinical assessment of the impairment, before establishing his/her fitness to drive.

Cannabis, alcohol and fatal road accidents

Introduction

This research aims to estimate the relative risks of responsibility for a fatal accident linked to driving under the influence of cannabis or alcohol, the prevalence of these influences among drivers and the corresponding attributable risk ratios. A secondary goal is to estimate the same items for three other groups of illicit drugs (amphetamines, cocaine and opiates), and to compare the results to a similar study carried out in France between 2001 and 2003.

Methodology

Police procedures for fatal accidents in Metropolitan France during 2011 were analyzed and 300 characteristics encoded to provide a database of 4,059 drivers. Information on alcohol and four groups of illicit drugs derived from tests for positivity and potential confirmation through blood analysis. The study compares drivers responsible for causing the accident, that is to say having directly contributed to its occurrence, to drivers involved in an accident for which they were not responsible, and who can be assimilated to drivers in general.

Results

The proportion of persons driving under the influence of alcohol is estimated at 2.1% (95% CI: 1.4–2.8) and under the influence of cannabis at 3.4% (2.9%-3.9%). Drivers under the influence of alcohol are 17.8 times (12.1–26.1) more likely to be responsible for a fatal accident, and the proportion of fatal accidents which would be prevented if no drivers ever exceeded the legal limit for alcohol is estimated at 27.7% (26.0%-29.4%). Drivers under the influence of cannabis multiply their risk of being responsible for causing a fatal accident by 1.65 (1.16–2.34), and the proportion of fatal accidents which would be prevented if no drivers ever drove under the influence of cannabis is estimated at 4.2% (3.7%-4.8%). An increased risk linked to opiate use has also been found to be significant, but with low prevalence, requiring caution in interpreting this finding. Other groups of narcotics have even lower prevalence, and the associated extra risks cannot be assessed.

Conclusion

Almost a decade separates the present study from a similar one previously conducted in France, and there have been numerous developments in the intervening years. Even so, the prevalence of drivers responsible for causing fatal accidents under the influence of alcohol or narcotics has stayed remarkably stable, as have the proportion of fatal accidents which could in theory be prevented if no drivers ever exceeded the legal limits. The overall number of deaths from traffic accidents has dropped sharply during this period, and the number of victims attributable to alcohol and/or cannabis declined proportionally. Alcohol remains the main problem in France. It is just as important to note that one in two drivers considered to be under the influence of cannabis was also under the influence of alcohol. With risks cumulating between the two, it is particularly important to point out the danger of consuming them together.

Patterns of facial trauma before and after legalization of marijuana in Denver, Colorado: A joint study between two Denver hospitals

INTRODUCTION

The effect of marijuana on human health has been studied extensively. Marijuana intoxication has been shown to affect performance, attention span, and reaction time. The public health relationship between trauma and cannabis use has also been studied, with mixed conclusions. In this report, the effect of marijuana legalization on many aspects of facial trauma at two hospitals in Denver, Colorado is examined.

METHODS

A retrospective review of the electronic medical records was undertaken. Mann-Whitney U tests were used to compare age of patients before and after legalization, and chi squared analyses were used to compare mechanism of injury, and fracture types before and after recreational marijuana legalization in Denver, Colorado. Geographical location of patients was also considered.

RESULTS

No significant increase was found in race before and after marijuana legalization (p=0.19). A significant increase in age was found before (M=39.54,SD=16.37), and after (M=41.38,SD=16.66) legalization (p<0.01). Maxillary and skull base fracture proportions significantly increased following legalization (p<0.001 and p<0.001respectively). No significant differences were seen in the proportion of patients who lived in urban and rural counties before and after legalization (p>0.05).

CONCLUSION

Public health efforts should be directed towards educating residents and visitors of Colorado on the effects and toxicology of marijuana. More epidemiologic studies are needed for further assessment of the long-term effects of the legalization of marijuana on the population.

Alcohol and Road Traffic Injuries in Latin America and the Caribbean: A Case-Crossover Study

BACKGROUND

This study reports dose-response estimates for the odds ratio (OR) and population attributable risk of acute alcohol use and road traffic injury (RTI).

METHODS

Data were analyzed on 1,119 RTI patients arriving at 16 emergency departments (EDs) in Argentina, Brazil, Costa Rica, Dominican Republic, Guatemala, Guyana, Mexico, Nicaragua, Panama, and Trinidad and Tobago. Case-crossover analysis, pair-matching the number of standard drinks consumed within the 6 hours prior to the RTI with 2 control periods (prior d/wk), was performed using fractional polynomial analysis for dose-response.

RESULTS

About 1 in 6 RTI patients in EDs were positive for self-reported alcohol 6 hours prior to the injury (country range 8.6 to 24.1%). The likelihood of an RTI with any drinking prior (compared to not drinking) was 5 times higher (country range OR 2.50 to 15.00) and the more a person drinks the higher the risk. Every drink (12.8 g alcohol) increased the risk of an RTI by 13%, even 1 to 2 drinks were associated with a sizable increase in risk of an RTI and a dose-response was found. Differences in ORs for drivers (OR = 3.51; 95% CI = 2.25 to 5.45), passengers (OR = 8.12; 95% CI = 4.22 to 15.61), and pedestrians (OR = 6.30; 95% CI = 3.14 to 12.64) and attributable fractions were noted. Acute use of alcohol was attributable to 14% of all RTIs, varying from 7% for females to 19% for being injured as a passenger.

CONCLUSIONS

The finding that the presence of alcohol increases risk among drivers and nondrivers alike may further help to urge interventions targeting passengers and pedestrians. Routine screening and brief interventions in all health services could also have a beneficial impact in decreasing rates of RTIs. Higher priority should be given to alcohol as a risk factor for RTIs, particularly in Latin America and the Caribbean.

The effect of central nervous system depressant, stimulant and hallucinogenic drugs on injury severity in patients admitted for trauma

OBJECTIVE

The effect of drugs other than alcohol on severity of trauma remains unclear. Pooled data analyses in previous studies that grouped substances with opposite effects on the central nervous system (CNS) may have masked the influence of substances on injury severity. The aim was to analyze the effect of stimulant, hallucinogenic and depressant drugs other than alcohol on injury severity in trauma patients.

METHODS

The presence of alcohol, stimulant drugs (cocaine, amphetamines and methamphetamines), depressant drugs (benzodiazepines, opiates, methadone and barbiturates) and hallucinogenic drugs (THC and PCP) was analyzed in 1187 patients between 16 and 70 years old admitted to a trauma hospital between November 2012 and June 2015. Injury severity was determined prospectively as the Injury Severity Score. A multivariate analysis was used to quantify the strength of association between exposure to substances and trauma severity, using the presence of alcohol as a stratification variable.

RESULTS

Drugs other than alcohol were found in 371 patients (31.3%): 32 (2.7%) stimulants, 186 (15.3%) depressants, 78 (6.6%) hallucinogenics and 75 (5.6%) polydrug use. The presence of CNS depressant substances was associated with increased injury severity only in patients also exposed to alcohol, with an adjusted odds ratio of 4.63 (1.37-15.60) for moderate injuries and 7.83 (2.53-24.21) for severe.

CONCLUSION

CNS depressant drugs had a strong influence on injury severity in patients who screened positive for alcohol consumption.

Alcohol use among fatally injured victims in São Paulo, Brazil: bridging the gap between research and health services in developing countries

BACKGROUND AND AIMS

Most studies reporting alcohol use among fatally injured victims are subject to bias, particularly those related to sample selection and to absence of injury context data. We developed a research method to estimate the prevalence of alcohol consumption and test correlates of alcohol use prior to fatal injuries.

DESIGN, SETTING AND PARTICIPANTS

Cross-sectional study based on a probability sample of fatally injured adult victims (n = 365) autopsied in São Paulo, Brazil. Victims were sampled within systematically selected 8-hour sampling blocks, generating a representative sample of fatal injuries occurring during all hours of the day for each day of the week between June 2014 and December 2015.

MEASUREMENTS

The presence of alcohol and blood alcohol concentration (BAC) were the primary outcomes evaluated according to victims' socio-demographic, injury context data (type, day, time and injury place) and criminal history characteristics.

FINDINGS

Alcohol was detected in 30.1% [95% confidence interval (CI) = 25.6-35.1)] of the victims, with a mean blood alcohol level (BAC) level of 0.11% w/v (95% CI = 0.09-0.13) among alcohol-positive cases. Black and mixed race victims presented a higher mean BAC than white victims (P = 0.03). Fewer than one in every six suicides tested positive for alcohol, while almost half of traffic-related casualties were alcohol-positive. Having suffered traffic-related injuries, particularly those involving vehicle crashes, and injuries occurring during weekends and at night were associated significantly with alcohol use before injury (P < 0.05).

CONCLUSIONS

Nearly one-third of fatal injuries in São Paulo between June 2014 and December 2015 were alcohol-related, with traffic accidents showing a greater association with alcohol use than other injuries. The sampling methodology tested here, including the possibility of adding injury context data to improve population-based estimates of alcohol use before fatal injury, appears to be a reliable and lower-cost strategy for avoiding biases common in death investigations.

The association between illicit drug use and infectious complications among trauma patients

Management of patients with traumatic injury is a complex endeavor requiring a concerted effort of multi-organ stabilization and prevention of septic shock. Given that traumatic injury is frequently mediated by illicit drug use, which has previously been associated with immune suppression, it is hypothesized that infectious complications may occur more prevalently in this patient population. In this study, we evaluate the incidence of infectious complications in trauma patients who screened positive for illicit drug abuse. The national trauma databank was queried for all patients who underwent laboratory evaluation for drug use between 2002 and 2009 and between 2013 and 2014. Patient demographics, clinical outcomes (injury severity score [ISS], intensive care unit length of stay [ILOS], hospital length of stay [HLOS], mortality, risk-adjusted ILOS [rILOS] or HLOS [rHLOS]) and infectious complications (pneumonia, superficial surgical site infection, organ space infection, deep space surgical site infection and urinary tract infection) were attained. Out of 5,564,821 incidents, 525,052 admissions met the inclusion criteria. Patients were 41 ± 19 years of age and 72 % were male. Patients positive for drug use were 1.1-fold more likely to develop pneumonia, 1.2-fold more likely to develop superficial site infection, and 1.3-fold more likely to develop organ space infection. No statistically significant variations in ILOS, HLOS, rILOS, rHLOS or mortality were noted. Traumatic patients who screen positive for illicit drug use are more likely to develop infectious complications. Therefore, vigilance and appropriate preventative measures should be considered in this unique group of patients.

Road traffic crash risk associated with benzodiazepine and z-hypnotic use after implementation of a colour-graded pictogram: a responsibility study

AIMS

To assess potential change in medicine exposure and association with the risk of road traffic crash across a time period that started before the implementation of a grading system warning of the effect of medicine on driving performance.

METHODS

Data from three French national databases were extracted and matched: the national health care insurance database, police reports and the national police database of injurious crashes. Drivers involved in such crashes in France, from July 2005 to December 2011 and identified by their national identifier, were included. Association with the risk of crash was estimated using a case-control analysis comparing benzodiazepine and z-hypnotic use among drivers responsible or not responsible for the crash.

RESULTS

Totals of 69 353 responsible and 73 410 non-responsible drivers involved in an injurious crash were included. Exposure to benzodiazepine anxiolytics was associated with an increased risk of being responsible for a road traffic crash during the pre-intervention period (OR = 1.42 [1.24-1.62]). The association disappeared in the post-intervention period, but became significant again thereafter. The risk of being responsible for a crash increased in users of z-hypnotics across the study period.

CONCLUSIONS

Our results question the efficacy of the measures implemented to promote awareness about the effects of medicines on driving abilities. Prevention policies relating to the general driving population, but also to healthcare professionals, should be reviewed.

Risk of motor vehicle collisions associated with medical conditions and medications: rationale and study protocol

BACKGROUND

Medical conditions and medications may be associated with motor vehicle collisions (MVCs), which pose a major public health problem worldwide. Further epidemiological assessment is necessary for certain diseases and medications. Moreover, since disease aetiology and patterns of medication use may differ among ethnicities and healthcare systems, a population-specific approach is necessary. The present epidemiological study is designed to assess the medical conditions and medications associated with the risk of fatal MVCs among at-fault drivers in the Korean population.

METHOD AND DESIGN

A retrospective cohort will be constructed for individuals who died in MVCs between 2005 and 2014 in the Korean Traffic Accident Analysis System database, which is linked to the Korean National Health Insurance database between 2002 and 2014. In order to compare medical conditions and medication use among drivers who died in a fatal MVC with the general population, standardised prevalence ratios will be calculated. In the culpability study, we will identify conditions and drugs associated with MVCs, comparing drivers with higher levels of responsibility to those with lower levels of responsibility. In the case-crossover study, the transient effects of medical conditions and medications will be examined using a conditional logistic regression model that adjusts for confounders.

DISCUSSION

The results of this study will help to characterise the associations of diseases and medications with fatal MVCs in an Asian population, with the goal of informing regulatory and clinical decision-making regarding patients with the relevant conditions and the establishment of strategies for improving traffic safety.

The epidemiologic principles underlying traffic safety study designs

This article describes the epidemiological principles underlying four observational study designs commonly used to assess traffic safety: the case-control, case-crossover, culpability and quasi-induced exposure designs. We focus in particular on the specific challenges for preventing bias using each design. Whereas recruiting controls representative of the source population poses a special challenge in case-control traffic safety studies, case-crossover designs are prone to recall bias, and culpability and quasi-induced exposure studies can be undermined by difficulties assigning crash responsibility. Using causal diagrams and worked examples, we provide a simple way to teach traffic safety designs to epidemiologists and to encourage proper application of epidemiological principles among researchers designing traffic safety studies.

Research Note: Cannabis and Driving — Research Needs and Issues for Transportation Policy

This paper summarizes current knowledge regarding the effects of cannabis use on driving. Psychopharmacological evidence has shown that cannabis, unlike alcohol, can be detected several days after consumption. Prevalence data has revealed that cannabis use is increasing, and that as many as 90% of study participants were willing to drive after consuming a typical dose. A review of laboratory studies found that cannabis and alcohol affect different driving tasks. When cannabis and alcohol use were evaluated in simulated and on-road driving situations, drivers were more aware of being intoxicated after using cannabis and thus invoked greater compensatory effort to offset impairment in the driving task. The effect of cannabis use on crash risk has shown that recent use increases crash risk, but not as much as alcohol consumption. This paper concludes that further research is needed before specific transportation policy can be developed for cannabis.

The effects of cannabis intoxication on motor vehicle collision revisited and revised

AIMS

To determine whether and to what extent acute cannabis intoxication increases motor vehicle crash risk.

DESIGN

Study 1 replicates two published meta-analyses, correcting for methodological shortcomings. Study 2 is an updated meta-analysis using 28 estimates from 21 observational studies. These included studies from three earlier reviews, supplemented by results from a structured search in Web of Science and Google Scholar, and by the personal libraries of the research team. Risk estimates were combined using random-effects models and meta-regression techniques.

SETTING

Study 1 replicates the analysis of Asbridge et al., based on nine studies from five countries, published 1982-2007; and Li et al., based on nine studies from six countries, published 2001-10. Study 2 involves studies from 13 countries published in the period 1982-2015.

PARTICIPANTS

In study 1, total counts extracted totalled 50 877 (27 967 cases, 22 910 controls) for Asbridge et al. and 93 229 (4236 cases and 88 993 controls) for Li et al. Study 2 used confounder-adjusted estimates where available (combined sample size of 222 511) and crude counts from the remainder (17 228 total counts), giving a combined sample count of 239 739.

MEASUREMENTS

Odds ratios (OR) were used from case-control studies and adjusted OR analogues from culpability studies. The impact of the substantial variation in confounder adjustment was explored in subsample analyses.

FINDINGS

Study 1 substantially revises previous risk estimates downwards, with both the originally reported point estimates lying outside the revised confidence interval. Revised estimates were similar to those of study 2, which found cannabis-impaired driving associated with a statistically significant risk increase of low-to-moderate magnitude [random-effects model OR 1.36 (1.15-1.61), meta-regression OR 1.22 (1.1-1.36)]. Subsample analyses found higher OR estimates for case-control studies, low study quality, limited control of confounders, medium-quality use data and not controlling for alcohol intoxication.

CONCLUSIONS

Acute cannabis intoxication is associated with a statistically significant increase in motor vehicle crash risk. The increase is of low to medium magnitude. Remaining selection effects in the studies used may limit causal interpretation of the pooled estimates.

Alcohol and drug involvement in motorcycle driver injuries in the city of Sao Paulo, Brazil: Analysis of crash culpability and other associated factors

BACKGROUND

Earlier studies have already identified that a greater proportion of injured drivers are under the effects of illicit drugs than alcohol in Brazil, but the crash risk attributable to each substance is still unknown.

METHODS

Injured motorcycle drivers who were involved in traffic accidents in the West Zone of the city of Sao Paulo were recruited for a cross-sectional study based on crash culpability analysis. Alcohol and drug positivity among drivers was evaluated according to their responsibility for the crash. Culpability ratios were generated based on the proportion of drivers who were deemed culpable in relation to those considered not culpable according to the use of drugs and alcohol.

RESULTS

Of the 273 drivers recruited, 10.6% tested positive for alcohol. Among those who were also tested for drugs (n=232), 20.3% had consumed either alcohol and/or other drugs, 15.5% of whom were positive only for drugs other than alcohol, specifically cannabis and cocaine. Drivers who tested positive for alcohol were significantly less likely to possess a valid driver's license and to report driving professionally, whereas those who had consumed only drugs were more likely to drive professionally. The culpability ratio estimated for alcohol-positive drivers was three times higher than that for alcohol-free drivers, showing a superior ratio than drivers who had consumed only drugs other than alcohol, who presented a 1.7 times higher culpability ratio than drug-free drivers.

CONCLUSION

Substance use was overrepresented among culpable motorcycle drivers, with alcohol showing a greater contribution to crash culpability than other drugs.

Restraint use and risky driving behaviors across drug types and drug and alcohol combinations for drivers involved in a fatal motor vehicle collision on U.S. roadways

Background

While driving impaired is a well-recognized risk factor for motor vehicle (MV) crash, recent trends in recreational drug use and abuse may pose increased threats to occupant safety. This study examines mechanisms through which drug and/or alcohol combinations contribute to fatal MV crash.

Methods

The Fatality Analysis Reporting System (FARS) for 2008–2013 was used to examine drugs, alcohol, driver restraint use, driver violations/errors and other behaviors of drivers of passenger vehicles who were tested for both alcohol and drugs (n = 79,932). Statistical analysis was based on Chi-square tests and multivariable logistic regression. Associations of restraint use and other outcomes with alcohol and drug use were measured by estimated odds ratios (ORs) and 95 % confidence intervals (95 % CIs).

Results

More than half (54.8 %) of the study population were positive for drugs or alcohol at the time of crash. Approximately half of drivers were belted, but this varied from 67.1 % (unimpaired) to 33.0 % (drugs plus alcohol). Compared to the unimpaired, the odds of a driver being unbelted varied: alcohol and cannabis (OR 3.70, 95 % CI 3.44–3.97), alcohol only (3.50,3.36–3.65), stimulants (2.13,1.91–2.38), depressants (2.09,1.89–2.31), narcotics (1.84,1.67–2.02) and cannabis only (1.55,1.43–1.67). Compared to belted drivers, unbelted drivers were over 4 times more likely to die. Driving violations varied across drug/drug alcohol combinations. Speed-related violations were higher for drivers positive for stimulants, alcohol, cannabis, and cannabis plus alcohol, with a more than two fold increase for alcohol and cannabis (2.36, 2.05, 2.71).

Conclusions

Mechanisms through which drugs, alcohol and substance combinations produce increased risks to occupant safety include lowered restraint use and increases in risky driving behaviors, including speeding, lane, passing, turning and signal/sign violations.

Prevalence of alcohol and drugs among motorcycle riders killed in road crashes in Norway during 2001-2010

The aim of the study was to examine the prevalence of alcohol and drugs in blood samples from motorcycle riders who died in road crashes in Norway from 2001 to 2010. An additional aim was to compare the prevalence of alcohol and drugs in blood samples from fatally injured motorcycle riders and car drivers who died during the same time period. Blood samples from motorcycle riders who died within 24h after the accident (n=207, 63% of all killed riders), were analysed for alcohol, psychoactive drugs (medicinal and illicit drugs). The cut-off concentrations for alcohol and drugs findings in blood samples (i.e., the drug concentrations above which a finding was regarded as positive) were set according to the legislative limits under the Norwegian Road Traffic Act. Results were assessed in relation to age, sex, time of the day and week, and single versus multiple-vehicle accidents. Alcohol or drugs were found in 27.1 percent of all investigated riders. For riders killed in single or multiple-vehicle accidents, alcohol or drugs were found in 44.6 and 15.3 percent, respectively. Alcohol was the most frequently found substance for all age groups and most prevalent in samples from riders below 25 years who died in single-vehicle accidents (45.8 percent). Drugs were most often found among riders between 25 and 34 years (19.6 percent in total and 25.9% for those killed in single-vehicle crashes). The prevalence of alcohol or drugs was highest among riders killed in single-vehicle accidents during weekend days and nights (60.9 and 65.2 percent). Alcohol and drugs were less often found in samples from killed motorcycles riders than in samples from car and van drivers (40.2 percent). For single-vehicle accidents, the total prevalence of alcohol or drugs among killed motorcycles riders and car drivers was 44.6 percent and 63.8 percent, respectively. The same pattern of alcohol and drugs was found among the two groups, except that the prevalence among motorcycle riders was lower compared to car drivers in all age groups and time periods, which may be related to the fact that they are more vulnerable for fatal injury compared to car drivers in similar accidents.

Drug use among drivers who drank on alcohol outlets from Porto Alegre, Brazil

BACKGROUND

Driving under the influence of multiple substances is a public health concern, but there is little epidemiological data about their combined use and putative impact on driving in low and middle-income countries where traffic crashes have been clustering in recent years. The aim of this study is to estimate the prevalence of alcohol and drug use - as well as their associated factors - among drivers in the context of alcohol outlets (AOs).

METHODS

A probability three-stage sample survey was conducted in Porto Alegre, Brazil. Individuals who were leaving AO were screened, with the selection of 683 drivers who met the inclusion criteria. Drivers answered a structured interview, were breathalyzed, and had their saliva collected for drug screening. Prevalences were assessed using domain estimation and logistic regression models assessed covariates associated with substance use.

FINDINGS

Benzodiazepines 3.9% (SE 2.13) and cocaine 3.8% (SE 1.3) were the most frequently detected drugs in saliva. Among drivers who were going to drive, 11% had at least one drug identified by the saliva drug screening, 0.4% two, and 0.1% three drugs in addition to alcohol. In multivariable analyses, having a blood alcohol concentration (BAC)>0.06% was found to be associated with a 3.64 times (CI 95% 1.79-7.39) higher chance of drug detection, compared with interviewees with lower BACs.

CONCLUSIONS

To drive under the influence of multiple substances is likely to be found in this setting, highlighting an association between harmful patterns of consume of alcohol and the misuse of other substances.

Commentary: why is the odds ratio for involvement in serious road traffic accident among drunk drivers in Norway and Finland higher than in other countries?

OBJECTIVE

Recent Norwegian and Finnish studies have found high odds ratios for serious or fatal injury in road traffic accidents among drivers after drinking alcohol. In this report we have compared the odds ratios with results from studies in other countries.

METHODS

A literature review was conducted.

RESULTS

The odds ratios were significantly higher than in countries where drunk driving is more common.

CONCLUSION

The calculated odds ratios are not only related to alcohol use or blood alcohol concentration per se but also related to the study design-for example, the inclusion of nonculpable drivers among cases-and confounding factors not included in statistical analysis; for example, risk-taking behavior. Those two issues may contribute to explaining why the reported odds ratios are higher for Norway and Finland.

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

This paper is a corrigendum to a previously published paper where errors were detected. The errors have been corrected in this paper. The paper is otherwise identical to the previously published paper. 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.