Risk Of Traffic Crashes Research Articles

Risks of seizure with fatal traffic crash at wheel in people with epilepsy

PurposeThe Japanese authorities require a 2-year seizure-free period for a driver’s license in people with epilepsy. To evaluate the stringency of the criteria, we calculated the risk of fatal traffic crashes by epileptic seizure and compared that to the risk of fatal traffic crashes among the general population. MethodsNation-wide questionnaire surveys to physicians and their patients with epilepsy were conducted to determine the rate of seizure recurrence after given seizure-free periods, average driving time and the rate of traffic crashes by epileptic seizures. The risk of fatal traffic crashes by epileptic seizures was calculated using the method proposed by the Driving License Committee of the EU. The risk of fatal traffic crashes among subgroups of the general population was calculated using the national statistics available. ResultsValid answers were obtained from a total of 548 patients of 138 epilepsy-specialists and 102 non epilepsy-specialist physicians. The relative risks of fatal traffic crashes in people with epilepsy with 1-year and 2-year seizure-free periods were 1.22 and 1.15, compared to the general population, while the ones in males in their twenties, people aged 60 and over, people aged 65 and over, and people aged 75 and over among the general population were 1.71, 1.31, 1.52 and 2.69, respectively. ConclusionThe risk of fatal traffic crashes in people with epilepsy for 1-year and 2-year seizure-free periods was estimated to be lower than that of some age groups in the general population. The increased risk in 1-year seizure freedom from that in 2-year seizure freedom was relatively small.

Longitudinal jerk and celeration as measures of safety in bus rapid transit drivers in Tehran

Traditionally, analysis of individual differences in road traffic crash risk has relied on after the fact crash data. Nowadays with the help of technologies like GPS, new measures are developed to assess driving risk, inferred from naturalistic driving behaviour of drivers. In this study, two main ways of modelling driver behaviour in naturalistic driving research were discussed and compared to each other. For this purpose, 176 Bus Rapid Transit (BRT) drivers were investigated during their normal driving on Tehran BRT routes. Their speed was continuously recorded by a smart phone app from which was derived deceleration, jerk and celeration measures. Analysis showed that all of the proposed measures had positive correlations with culpable crashes and that one of the jerk variables yielded the highest correlation. Measurements of speed derivatives like jerk and celeration can help to identify dangerous driving styles in public transportation and reduce the number of crashes. Although the results of this study are encouraging, further studies for longer periods are needed to improve the reliability of the measures.

Short-term prediction of safety and operation impacts of lane changes in oscillations with empirical vehicle trajectories

Lane changes made during traffic oscillations on freeways largely affect traffic safety and could increase collision potentials. Predicting the impacts of lane change can help to develop optimal lane change strategies of autonomous vehicles for safety improvement. The study aims at proposing a machine learning method for the short-term prediction of lane-changing impacts (LCI) during the propagation of traffic oscillations. The empirical lane-changing trajectory records were obtained from the Next Generation Simulation (NGSIM) platform. A support vector regression (SVR) model was trained in this study to predict the LCI on the crash risks and flow change using microscopic traffic variables such as individual speed, gap and acceleration on both original lanes and target lanes. Sensitivity analyses were conducted in the SVR to quantify the contributions of correlative lane changing factors. The results showed that the trained SVR model achieved an accuracy of 72.81 % for the risk of crashes and 95.34 % in predicting the flow change. The sensitivity analysis explored the optimal speed and acceleration for the lane changer to achieve the lowest time integrated time-to-collision (TIT) value for safety maximization. Finally, we compared the LCI for motorcycles, automobiles and trucks as well as the LCI for both lane-changing directions (from left to right and from right to left). It was found that motorcycles conducted lane changes with smaller gaps and larger speed differences, which brings the highest crash risks. Passenger cars were found to be the safest when they conduct lane changes. Lane changes to the right had more negative impacts on traffic flow and crash risks.

Exploring the Effect of Driving Factors on Traffic Crash Risk among Intoxicated Drivers: A case Study in Wujiang.

Intoxicated driving is a threat to both drivers and other road users. Exploring the association between intoxicated driving factors and traffic crashes is essential for taking effective countermeasures. Most previous works have studied the relation between intoxicated driving and traffic crash based on some large-sized cities. The current study aims to evaluate the effect of driving factors on traffic crashes among intoxicated drivers in a small-sized city in China. Descriptive statistics and binary logistic regression analysis are performed to guide the study, and the data (N = 1010) for the period 2016–2017 in Wujiang (i.e., a small-sized city in China) are employed as the target samples. The results demonstrate age, years of driving experience, road position, week, hour and blood alcohol concentration (BAC) are associated with traffic crashes in Wujiang. Specifically, the age of “18–25”, the years of driving experience of “≤2”, the “road intersection”, the “weekend”, the period of “0:00–6:59” and the BAC of “above 150 mg/100 mL” are more likely to cause traffic crashes among intoxicated drivers. The findings can be referred to make some targeted policies or measures to relieve Wujiang’s intoxicated driving situation and reduce the number of crashes caused by intoxicated driving.

Trends in benzodiazepine anxiolytics and z-hypnotics use among French drivers involved in road traffic crashes from 2005 to 2015: a responsibility case-control study

BackgroundIn France, benzodiazepine anxiolytics and z-hypnotics (zolpidem and zopiclone) account for the largest share of road traffic crash risk attributable to exposure to prescription drugs. The aim of this study was to monitor the evolution of the use of these prescription drugs and their association with crash risk over a period that began before the implementation of a color-graded pictogram system printed on prescription drug boxes.MethodsData from three French national databases were extracted and linked: the national health care insurance database, police reports, and the national police database of injurious crashes. Drivers involved in an injurious crash in France, from July 2005 to December 2015, and identified by their national identifier were included. The association with crash risk was estimated using a responsibility analysis comparing the use of benzodiazepines and z-hypnotics among drivers responsible or not for the crash.ResultsA total of 97,936 responsible and 103,522 non-responsible drivers involved in an injurious crash were included. The proportion of drivers exposed to benzodiazepine anxiolytics or z-hypnotics remained stable among responsible and non-responsible drivers. Among controls from the general population, the proportion of exposed individuals tended to increase. The association with crash risk remained almost constant over the study period. The odds-ratio for benzodiazepines ranged between 1.42 [1.24–1.62] at the beginning of the study period and 1.27 [1.09–1.47] at the end.ConclusionGiven the increase in exposure in the control group from the general population, the stability of exposure for responsible and non-responsible drivers can be interpreted as a relative effectiveness of the pictogram on driver exposure levels. On the other hand, while the intrinsic effect of a prescription drug cannot be modified, a decrease in risk could have been expected if drivers adapted their behavior as promoted by the pictogram. Our results therefore suggest that no significant change occurred in driving behaviors or consumption patterns.

Speeding Violation Type Prediction Based on Decision Tree Method: A Case Study in Wujiang, China

The speeding violation has become a key concern in the traffic safety management, as it increases the risk of traffic crashes, as well as the severity of these crashes. This uncivilized phenomenon is prominent and presents an increasing trend in Wujiang in recent years, which severely endangers the road traffic safety. This study is approved by the Traffic Police Brigade of Wujiang Public Security Bureau and aims to explore the characteristic of the speeding violation behaviour and attempt to make an effective prediction about it. This study proposes a speeding violation type (including type 1 and type 2) prediction method using electronic law enforcement data obtained from the public security administration of Wujiang. Before the prediction, a speeding violation influence factor analysis based on the binary logical regression model is proposed. The binary logical regression analysis identifies that the license plate, season, speeding area, position, and rainfall are the influence factors of Wujiang’s speeding violation. Then a decision tree method is used to predict the speeding violation type according to the influence factors, and from which the speeding violation situations can be determined. The prediction results demonstrate that under the hypothetical conditions, the high speeding violation level (i.e., type 2) tends to occur under high rainfall environment, and the foreign license plate and autumn present a larger probability of high speeding violation level than the local license plate and other seasons (i.e., spring, summer, and winter), respectively. Finally, a model comparison between the proposed method and other tree-based approaches is conducted. The comparison results show that the decision tree method outperforms other methods in prediction performance (including accuracy, precision, recall, and classification error), runtime, and ROC curve, which indicates that the decision tree method is feasible in predicting the speeding violation type of Wujiang. Based on the findings, the traffic managers can macroscopically grasp the speeding violation situation of the whole road networks, which can be referred for making the related polices and taking intervention measures.

Exploring the prevalence and factors associated with self-reported traffic crashes among app-based motorcycle taxis in Vietnam

Motorcycle taxis play an important role in many developing countries, particularly in servicing areas where conventional public transport is not available. This form of transport has become more popular in recent years since online ride-hailing companies launched motorcycle taxi services. However, little is known about traffic crash risks among app-based motorcycle taxi riders. This study therefore aimed to investigate the prevalence and factors associated with road traffic crashes among app-based motorcycle taxi riders. A field survey and online survey were undertaken to obtain information about riders’ socio-demographics, work patterns, travel behaviour and crash involvement. A total of 602 valid survey responses from riders were obtained across three cities in Vietnam, including 571 males and 31 females. The overall reported prevalence of road traffic crashes among app-based motorcycle taxi riders over a one-year period was 30%. Binary logistic regression modelling showed that traffic crashes were associated with non-students, low education levels, high daily travel distances, regular smoking, and using a mobile phone while driving. Despite regulation of online ride-hailing motorcycle taxi services in Vietnam, the reported prevalence of crashes among riders is considered to be relatively high. Targeted interventions to reduce the risk of being involved in a crash should be considered, such as increasing road safety education for non-student riders and imposing a daily travel distance limit for riders.

Motorcycle taxi programme is associated with reduced risk of road traffic crash among motorcycle taxi drivers in Kampala, Uganda

SafeBoda is a transportation company that provides road safety training and helmets to its motorcycle taxi drivers in Kampala. We sought to determine whether risk of road traffic crash (RTC) was lower in SafeBoda compared to regular (non-SafeBoda) motorcycle taxi drivers during a 6-month follow-up period. We collected participant demographic and behavioural data at baseline using computer-assisted personal interview, and occurrence of RTC every 2 months using text messaging and telephone interview from a cohort of 342 drivers. There were 85 crashes (31 in SafeBoda and 54 in regular drivers) during follow-up. Over the 6-month follow-up period, SafeBoda drivers were 39% less likely to be involved in a RTC than regular drivers after adjusting for age, possession of a driver’s license, and education (RR: 0.61, 95% CI: 0.39–0.97, p = .04). These findings suggest that the SafeBoda programme results in safer driving and fewer RTCs among motorcycle taxi drivers in Kampala.

The effect of aggressive driver behaviour, violation and error on vehicle crashes involvement in Jordan

The current study aims at examining the effect of aggressive driver behaviour, violation and error on motor vehicle crashes and investigating the factor structure of the Driver Behaviour Questionnaire (DBQ) factors on the crash involvement in Jordan. This is a cross-sectional study design conducted during September, 2016 to May 2017 in Amman, the capital of Jordan. The study included a representative sample of aged 22-65 years old 1450 drivers of which 1084 drivers agreed to participate (74.7%). The Manchester DBQ instrument was used to measure the aggressive, aberrant driving behaviours leading to crashes. Univariate and Multivariate logistic regression statistical analysis were performed. Out of a total 1084 responding drivers, 778 (71.7%) were males and 306 (28.3%) were females. The study revealed a statistically significant difference between males and females drivers in terms of age (p < 0.001), education (p < 0.001), occupation (p = 046), marital status (p < 0.001), income (p < 0.001), driving experience (p < 0.001) and seat belts use (p < 0.001). Most of drivers admitted to ever had crashes (p < 0.001), careless driving (p < 0.001), having excessive speed (p < 0.001), smoking while driving (p < 0.001), crossing red traffic light (p < 0.001), using mobile phone (p < 0.001) and using SMS while driving (p = 0.041). The DBQ mean scores of males were significantly higher in violations, error and frequently reported lapses whereas the mean driving skills score was similar between male and female divers. The factor included nine items of violations, six items of errors and five items of lapses in the Jordanian driver sample. Further, multivariate logistic regression analysis revealed violations, mobile phone use, excessive speed, driving skills, errors, lapses and type and size of vehicle significantly increased the risk of crash involvement. The results of the study demonstrated the increased risk of road traffic crashes among young Jordanian driverswhich had history of injuries at the time of crash (37.8%). Excessive speeding and mobile phone were the strongest predictors for the crash occurrence.

Life-threatening alcohol-related traffic crashes in adverse weather: a double-matched case–control analysis from Canada

ImportanceDrunk driving is a major cause of death in North America, yet physicians rarely counsel patients on the risks of drinking and driving.ObjectiveTo test whether the risks of a life-threatening...

Crashes when It Splashes: Link between Precipitation Type and Fatal Accidents in the United States

Introduction: We conduct a comprehensive national assessment of the risk of fatal traffic crashes by examining the association of precipitation intensity with fatal accidents, specifically investig...

Freeway crash risks evaluation by variable speed limit strategy using real-world traffic flow data

The primary objective of this study is to evaluate the real-time crash risk of freeways by using real-world traffic flow data. The crash risk expressed as the potential crash likelihood is assessed under variable speed limit (VSL) and without VSL, in which both spatial correlation between different sites and temporal similarity are contained. Traffic flow data of Whitemud Drive network (WMD) in Canada is used to perform the relevant analysis, including VSL implementation analysis, traffic flow similarity analysis, crash risk and congestion analysis. Analytical results demonstrate that the average traffic flow under VSL schemes 1, 2, 3 and 4 are highly correlated from spatial-temporal perspective. The crash likelihoods and congestions under these VSL schemes are greatly improved. The best VSL control scheme, the most dangerous area and time, together with the most congested station of WMD are eventually determined. Subsequently, a t-test is employed to examine the significance of these results. t-Test results suggest that the improvement degree between crash risk and congestion under the best VSL control scheme show a difference, i.e., the best VSL control scheme can reduce the crash risk of moderate risk area more than high risk area, while it may have a larger melioration on the most congested area than the relatively uncongested area. Finally, these results are considered to have the potential reference in the mitigation of WMD traffic issues.

Association of Cataract Surgery With Traffic Crashes

Cataracts are the most common cause of impaired vision worldwide and may increase a driver's risk of a serious traffic crash. The potential benefits of cataract surgery for reducing a patient's subsequent risk of traffic crash are uncertain. To conduct a comprehensive longitudinal analysis testing whether cataract surgery is associated with a reduction in serious traffic crashes where the patient was the driver. Population-based individual-patient self-matching exposure-crossover design in Ontario, Canada, between April 1, 2006, and March 31, 2016. Consecutive patients 65 years and older undergoing cataract surgery (n = 559 546). First eye cataract extraction surgery (most patients received second eye soon after). Emergency department visit for a traffic crash as a driver. Of the 559 546 patients, mean (SD) age was 76 (6) years, 58% were women (n = 326 065), and 86% lived in a city (n = 481 847). A total of 4680 traffic crashes (2.36 per 1000 patient-years) accrued during the 3.5-year baseline interval and 1200 traffic crashes (2.14 per 1000 patient-years) during the 1-year subsequent interval, representing 0.22 fewer crashes per 1000 patient-years following cataract surgery (odds ratio [OR], 0.91; 95% CI, 0.84-0.97; P = .004). The relative reduction included patients with diverse characteristics. No significant reduction was observed in other outcomes, such as traffic crashes where the patient was a passenger (OR, 1.03; 95% CI, 0.96-1.12) or pedestrian (OR, 1.02; 95% CI, 0.88-1.17), nor in other unrelated serious medical emergencies. Patients with younger age (OR, 1.27; 95% CI, 1.13-1.14), male sex (OR, 1.64; 95% CI, 1.46-1.85), a history of crash (baseline OR, 2.79; 95% CI, 1.94-4.02; induction OR, 4.26; 95% CI, 2.01-9.03), more emergency visits (OR, 1.34; 95% CI, 1.19-1.52), and frequent outpatient physician visits (OR, 1.17; 95% CI, 1.01-1.36) had higher risk of subsequent traffic crashes (multivariable model). This study suggests that cataract surgery is associated with a modest decrease in a patient's subsequent risk of a serious traffic crash as a driver, which has potential implications for mortality, morbidity, and costs to society.

Optical illusions and life-threatening traffic crashes: A perspective on aerial perspective

Aerial perspective illusion is a feature of visual perception where landscapes appear relatively close in clear light and distant in dim light. We hypothesized that bright sunlight might cause drivers to perceive distant terrain as relatively close and misinterpret the approach speed of surrounding landscape as unduly slow. This hypothesis would mean, in turn, that drivers in bright sunlight may underestimate their progress on the road, compensate by traveling at a faster baseline speed, and ultimately increase the prevailing risk of a life-threatening traffic crash.We conducted three pilot studies to illustrate how the illusion might contribute to a life- threatening traffic crash. The first illustration used a questionnaire to demonstrate that most respondents were mistaken when judging the distance between simple balls in different positions. The second illustration involved an experimental manipulation to assess whether aerial perspective influenced judgments about the relative positions of vehicles in traffic. The third illustration analyzed a segment of high-volume fast-speed traffic and found an increased frequency of speeding under bright sunlight.Together with past work based on the visual arts, these examples illustrate how an aerial perspective illusion can affect distance perception, may appear in realistic traffic situations, and could potentially contribute to the risk of a life-threatening traffic crash. An awareness of this hypothesis might lead to applications on how optical illusions could extend to everyday traffic and might potentially inform safety warnings to prevent life- threatening crashes.

“Positive” urine testing for Cannabis is associated with increased risk of traffic crashes

Although recent Cannabis use is widely reported to be associated with drug-related traffic accidents, the evidence that Cannabis users show an increased risk of being involved in road crashes is still not unequivocally proved. The purpose of the present work is to provide an objective assessment of this hypothesis, by comparing the frequency of occurrence of positive urine analyses in drivers involved in traffic accidents (n = 1406) with that observed in a control population undergoing mandatory urine drug testing (n = 1953). Urine analyses for drugs of abuse were performed by screening immunometric techniques followed by confirmation with UHPLC-QQQ MS, adopting a cut-off concentration for THC-COOH of 15 ng/mL. A case was classified as “positive” when a driver admitted to hospital for road traffic injuries showed urine concentrations of THC-COOH higher than the cut-off. All samples showing positive results for any other controlled drug in urine or blood alcohol concentrations >0.5 mg/mL were excluded from the study. Subjects positive to THC-COOH, and negative to all the other tested substances were 116 in Group 1 (8.2%) and 16 in Group 2 (0.8%). Subjects resulting negative to any tested substances were 1290 in Group 1 and 1937 in Group 2. The frequency of THC-COOH detection in the two groups was compared by using the “chi square” test, which resulted = 119.57, i.e. highly significant (P <<< 0.01). The Odds Ratio of the two groups was =10.88, showing a high degree of association between the presence of THC-COOH in urine and the occurrence of traffic accidents (P < 0.0001). The presented data, proving a high degree of association between Cannabis use and the occurrence of traffic accidents with injuries of the driver, support the use of urine testing for Cannabis in the procedures for the issuing of the driving licence, particularly in the case of subjects formerly or presently using Cannabis. This finding looks even more relevant in the present times, because of the increasing success of the policies of legalization of Cannabis for medical and non-medical purposes.

Utilizing Structural Equation Modeling and Segmentation Analysis in Real-time Crash Risk Assessment on Freeways

The study aimed to utilize Structural Equation Modeling (SEM) and K-means clustering for predicting real-time crash risks on freeways. The SEM was used to transform a number of correlated traffic variables into four independent latent traffic factors, and to establish the interrelationships among the traffic variables and crash risks. The segmentation analysis based on K-means clustering was then conducted to investigate the main traffic factors affecting crash risks in various traffic regimes. It was found that: (a) The measurement equations in SEM can effectively account for the correlations among traffic variables by transforming numerous correlated traffic variables into several latent traffic variables; (b) The SEM can both capture the direct and indirect effects of traffic flow variables on crash risks. This promotes a better understanding how traffic conditions affect crash risks; (c) The SEM produces more accurate estimates of crash risks than existing modeling technique. It can increase the crash prediction accuracy by an average of 7.6% compared with the commonly used logistic regression; and (d) Segmentation analysis results suggested that the traffic factors contributing to crash risks are various across different traffic regimes. The proactive crash prevention strategies for different traffic regimes were discussed based on the findings in the segmentation analysis.

The impact of vehicle moving violations and freeway traffic flow on crash risk: An application of plugin development for microsimulation.

This paper presents the use of the Aimsun microsimulation program to simulate vehicle violating behaviors and observe their impact on road traffic crash risk. Plugins for violations of speeding, slow driving, and abrupt stopping were developed using Aimsun’s API and SDK module. A safety analysis plugin for investigating probability of rear-end collisions was developed, and a method for analyzing collision risk is proposed. A Fuzzy C-mean Clustering algorithm was developed to identify high risk states in different road segments over time. Results of a simulation experiment based on the G15 Expressway in Shanghai showed that abrupt stopping had the greatest impact on increasing collision risk, and the impact of violations increased with traffic volume. The methodology allows for the evaluation and monitoring of risks, alerting of road hazards, and identification of hotspots, and could be applied to the operations of existing facilities or planning of future ones.

Prescription medicine use by pedestrians and the risk of injurious road traffic crashes: A case-crossover study.

BackgroundWhile some medicinal drugs have been found to affect driving ability, no study has investigated whether a relationship exists between these medicines and crashes involving pedestrians. The aim of this study was to explore the association between the use of medicinal drugs and the risk of being involved in a road traffic crash as a pedestrian.Methods and findingsData from 3 French nationwide databases were matched. We used the case-crossover design to control for time-invariant factors by using each case as its own control. To perform multivariable analysis and limit false-positive results, we implemented a bootstrap version of Lasso. To avoid the effect of unmeasured time-varying factors, we varied the length of the washout period from 30 to 119 days before the crash. The matching procedure led to the inclusion of 16,458 pedestrians involved in an injurious road traffic crash from 1 July 2005 to 31 December 2011. We found 48 medicine classes with a positive association with the risk of crash, with median odds ratios ranging from 1.12 to 2.98. Among these, benzodiazepines and benzodiazepine-related drugs, antihistamines, and anti-inflammatory and antirheumatic drugs were among the 10 medicines most consumed by the 16,458 pedestrians. Study limitations included slight overrepresentation of pedestrians injured in more severe crashes, lack of information about self-medication and the use of over-the-counter drugs, and lack of data on amount of walking.ConclusionsTherapeutic classes already identified as impacting the ability to drive, such as benzodiazepines and antihistamines, are also associated with an increased risk of pedestrians being involved in a road traffic crash. This study on pedestrians highlights the necessity of improving awareness of the effect of these medicines on this category of road user.

New, Occasional, and Frequent Use of Zolpidem or Zopiclone (Alone and in Combination) and the Risk of Injurious Road Traffic Crashes in Older Adult Drivers: A Population-Based Case-Control and Case-Crossover Study.

BackgroundPrevious studies on the effect of zolpidem or zopiclone use on the risk of road traffic crashes (RTCs) have shown mixed results.ObjectiveOur objective was to determine the association between zolpidem or zopiclone use (as separate drugs or combined) and the occurrence of injurious RTCs among older adult drivers.MethodsThis was a population-based matched case–control and case–crossover study based on secondary data linked together from Swedish national registers. Cases were drivers aged 50–80 years involved in a vehicle crash resulting in injuries between January 2006 and December 2009 for the case–control study (n = 27,096) and from February 2006 to December 2009 for the case–crossover study (n = 26,586). For the first design, four controls were matched to each case by sex, age, and residential area, and exposure was categorized into new, occasional, and frequent use of zolpidem only, zopiclone only, and combined zolpidem and zopiclone. For the case–crossover study, newly dispensed zolpidem or zopiclone users were assessed during the 28 days prior to the crash and compared with an equally long control period using a 12-week washout period. Matched adjusted odds ratios (OR) were computed using conditional logistic regression.ResultsIncreased ORs for all users were observed. In the case–control study, the highest odds were seen among newly initiated zolpidem-only users involved in single-vehicle crashes (adjusted OR 2.27; 95% confidence interval [CI] 1.21–4.24), followed by frequent combined zolpidem and zopiclone users [adjusted OR 2.20; CI 1.21–4.00]. In the case–crossover, newly initiated treatment with zolpidem or zopiclone showed an increased risk that was highest in the 2 weeks after the start of the treatment (OR 2.66; 95% CI 1.04–6.81).ConclusionsThese results provide more compelling evidence for the role of zolpidem or zopiclone in the occurrence of RTCs among older adults, not only in frequent users, but also at the beginning of treatment.Electronic supplementary materialThe online version of this article (doi:10.1007/s40263-017-0445-9) contains supplementary material, which is available to authorized users.

Road traffic crash risk associated with prescription of hydroxyzine and other sedating H1-antihistamines: A responsibility and case-crossover study

BackgroundH1 antihistamines differ from each other by their ability to cross the blood-brain barrier. The resulting sedating effect can be sought in therapy but may be a driving hazard. The aim of this study was to estimate the impact of sedating H1-antihistamines on the risk of road traffic crash, with a particular focus on hydroxyzine which is also indicated as an anxiolytic in France. MethodsThe study consisted in extracting and matching data from three French nationwide databases: the national healthcare insurance database, police reports and the police national database of injurious crashes. All sedating H1-antihistamines, including hydroxyzine, were considered in the study. A case-control analysis, in which responsible drivers were cases and non-responsible were controls was performed. A case-crossover analysis, comparing for the same subject exposure during a period immediately before the crash with exposure during an earlier period, was also conducted. ResultsThe extraction and matching procedures over the July 2005-December 2011 period led to the inclusion of 142,771 drivers involved in an injurious road traffic crash. The responsibility study found an increased risk of being responsible for an injurious road traffic crash in hydroxyzine users who were registered with a long-term chronic disease (mostly psychiatric disorders) on the day of the crash (OR=1.67 [1.22–2.30]). Among them, the risk was even higher in drivers with highest exposure levels (OR=2.60 [1.23–5.50]). There was no impact of sedating H1 antihistamine treatment initiation on the risk of crash. ConclusionEven if it is difficult to disentangle the part of the increased risk that would be causally related to hydroxyzine and the part related to behaviours of patients with a heavy psychiatric disorder, our study raises the alarm on the crash risk linked to hydroxyzine utilization in countries in which the anxiolytic indication is widespread.