Herbert Chan

Cell phone use and traffic crash risk: a culpability analysis

BACKGROUND The use of a cell phone or communication device while driving is illegal in many jurisdictions, yet evidence evaluating the crash risk associated with cell phone use in naturalistic settings is limited. This article aims to determine whether cell phone use while driving increases motor vehicle crash culpability. Method Drivers involved in crashes where police reported cell phone use (n = 312) and propensity matched drivers (age, sex, suspect alcohol/drug impairment, crash type, date, time of day, geographical location) without cell phone use (n = 936) were drawn from Insurance Corporation of British Columbia Traffic Accident System data. A standardized scoring tool, modified to account for Canadian driving conditions, was used to determine crash culpability from police reports on all drivers from the crashes. The association between crash culpability and cell phone use was determined, with additional subgroup analyses based on crash severity, driver characteristics and type of licence. RESULTS A comparison of crashes with vs without cell phones revealed an odds ratio of 1.70 (95% confidence interval 1.22-2.36; P = 0.002). This association was consistent after adjustment for matching variables and other covariates. Subgroup analyses demonstrated an association for male drivers, unimpaired drivers, injured and non-injured drivers, and for drivers aged between 26 and 65 years. CONCLUSIONS Crash culpability was found to be significantly associated with cell phone use by drivers, increasing the odds of a culpable crash by 70% compared with drivers who did not use a cell phone. This increased risk was particularly high for middle-aged drivers.

Reduction in Fatalities, Ambulance Calls, and Hospital Admissions for Road Trauma After Implementation of New Traffic Laws

OBJECTIVES We evaluated the public health benefits of traffic laws targeting speeding and drunk drivers (British Columbia, Canada, September 2010). METHODS We studied fatal crashes and ambulance dispatches and hospital admissions for road trauma, using interrupted time series with multiple nonequivalent comparison series. We determined estimates of effect using linear regression models incorporating an autoregressive integrated moving average error term. We used neighboring jurisdictions (Alberta, Saskatchewan, Washington State) as external controls. RESULTS In the 2 years after implementation of the new laws, significant decreases occurred in fatal crashes (21.0%; 95% confidence interval [CI]=15.3, 26.4) and in hospital admissions (8.0%; 95% CI=0.6, 14.9) and ambulance calls (7.2%; 95% CI=1.1, 13.0) for road trauma. We found a very large reduction in alcohol-related fatal crashes (52.0%; 95% CI=34.5, 69.5), and the benefits of the new laws are likely primarily the result of a reduction in drinking and driving. CONCLUSIONS These findings suggest that laws calling for immediate sanctions for dangerous drivers can reduce road trauma and should be supported.

The impact on alcohol-related collisions of the partial decriminalization of impaired driving in British Columbia, Canada

INTRODUCTION The purpose of this paper is to assess the impact of administrative sanctions introduced as part of a new law for drinking drivers in British Columbia, Canada. The new law, known as immediate roadside prohibitions (IRP), aimed to increase the efficiency of police and courts for processing drinking drivers, thereby increasing the certainty of their being apprehended and punished. However, in order to maintain these efficiencies, sanctions under this new law largely replaced laws under the Criminal Code of Canada for Driving While Impaired (DWI) by alcohol, which had more severe penalties but lower certainty of punishment. We examined whether the intervention was related to abrupt significant declines in three types of alcohol-related collisions (i.e. fatalities, injuries or property damage only) compared to the same type of collisions without alcohol involvement. METHODS An interrupted time series design, with a non-equivalent control was used, testing for an intervention effect. Monthly rates of the three types of collisions with and without alcohol involvement were calculated for the 15-year period before and the 1-year period after implementation of the new law. ARIMA time series analysis was conducted controlling for trend effects, seasonality, autocorrelation, and collisions without alcohol. RESULTS Significant average declines (p<0.05) in alcohol-related collisions were found as follows: 40.4% for fatal collisions, 23.4% for injury collisions and 19.5% for property damage only collisions. No significant effects were found for any of the three comparable non-alcohol-related types of collisions. CONCLUSIONS These results suggest that provincial law of administrative sanctions for drinking drivers and associated publicity was more effective for minimizing alcohol-related collisions than laws under the Canadian Criminal Code.

Police Documentation of Alcohol Involvement in Hospitalized Injured Drivers

Objective: Injured drivers with blood alcohol concentration (BAC) above the legal limit are rarely convicted of impaired driving. One explanation is that police may have difficulty recognizing alcohol intoxication in injured drivers. In this study, we compare police documentation of alcohol involvement with BAC measured on arrival at a hospital. Our objectives were to determine how often police document alcohol involvement in injured drivers with BAC ≥ 0.05 percent and identify factors that influence police documentation of alcohol involvement. Methods: We included injured drivers (1999–2003) who were admitted to a British Columbia trauma center or treated in the Vancouver General Hospital emergency department. We used probabilistic linkage to obtain police collision reports. Police were considered to have indicated alcohol involvement if (1) police documented that alcohol contributed to the crash, (2) the driver received an administrative sanction for impaired driving, or (3) the driver was criminally convicted of impaired driving. The proportion of drivers for whom police indicated alcohol involvement was determined relative to age, gender, BAC levels, crash severity, and crash characteristics. Multivariate logistic regression was used to identify factors independently associated with police indication of alcohol involvement. Results: Two thousand four hundred and ten injured drivers (73.5% male) were matched to a police report. Overall, 857 (35.6%) drivers tested positive for alcohol (BAC ≥ 0) and 736/857 (85.9%) of alcohol-positive drivers had a BAC ≥ 0.05 percent (the legal limit in British Columbia). Of the 736 drivers with a BAC > 0.05 percent at time of admission, police indicated alcohol involvement in 530 (72.0%). The criminal code conviction rate for impaired driving was 4.7 percent for drivers with 0.08 percent ≤ BAC < 0.16 percent and 13.6 percent for drivers with BAC > 0.16 percent. The following factors were associated with higher odds of police indicating alcohol involvement: (1) increasing blood alcohol levels, (2) a prior record of impaired driving, (3) involvement in a single-vehicle crash, (4) involvement in a nighttime crash, and (5) traffic violations or unsafe driving actions recorded by police. Conclusions: Police recognized and documented alcohol involvement in 72 percent of injured drivers with BAC ≥ 0.05 percent. Police documentation of alcohol involvement was more common at higher BAC levels, in nighttime or single-vehicle crashes, for drivers who committed traffic violations or drove unsafely, and for drivers with a prior record of impaired driving. The low conviction rate of injured impaired drivers does not appear to be due to police inability to recognize alcohol involvement.

Prevalence of alcohol and drug use in injured British Columbia drivers

Objectives Determine the prevalence of drug use in injured drivers and identify associated demographic factors and crash characteristics. Design Prospective cross-sectional study. Setting Seven trauma centres in British Columbia, Canada (2010–2012). Participants Automobile drivers who had blood obtained within 6 h of a crash. Main outcome measures We analysed blood for cannabis, alcohol and other impairing drugs using liquid chromatography/mass spectrometry (LCMS). Results 1097 drivers met inclusion criteria. 60% were aged 20–50 years, 63.2% were male and 29.0% were admitted to hospital. We found alcohol in 17.8% (15.6% to 20.1%) of drivers. Cannabis was the second most common recreational drug: cannabis metabolites were present in 12.6% (10.7% to 14.7%) of drivers and we detected Δ-9-tetrahydrocannabinol (Δ-9-THC) in 7.3% (5.9% to 9.0%), indicating recent use. Males and drivers aged under 30 years were most likely to use cannabis. We detected cocaine in 2.8% (2.0% to 4.0%) of drivers and amphetamines in 1.2% (0.7% to 2.0%). We also found medications including benzodiazepines (4.0% (2.9% to 5.3%)), antidepressants (6.5% (5.2% to 8.1%)) and diphenhydramine (4.7% (3.5% to 6.2%)). Drivers aged over 50 years and those requiring hospital admission were most likely to have used medications. Overall, 40.1% (37.2% to 43.0%) of drivers tested positive for alcohol or at least one impairing drug and 12.7% (10.7% to 14.7%) tested positive for more than one substance. Conclusions Alcohol, cannabis and a broad range of other impairing drugs are commonly detected in injured drivers. Alcohol is well known to cause crashes, but further research is needed to determine the impact of other drug use, including drug–alcohol and drug–drug combinations, on crash risk. In particular, more work is needed to understand the role of medications in causing crashes to guide driver education programmes and improve public safety.

Culpability analysis is still a valuable technique

The February 2013 issue of the IJE included our study which used culpability analysis to examine the association of cellphone use with motor vehicle crashes. In a commentary in the same issue, Sanghavi stated that ‘culpability analysis won’t help us understand crash risk due to cellphones’. Sanghavi’s categorical rejection of culpability analysis is unfortunate and seems based on a misunderstanding of the method and perhaps aversion to the term ‘culpability’. Culpability analysis, also referred to as responsibility analysis, is a powerful technique with a long history in road safety research. The method was first used in 1951 by Smith and Popham to study the association of alcohol with crashes and has since been applied numerous times to the study of crash risk. A standard feature of the culpability design is that all drivers have been involved in a crash and are therefore subject to standard legal or medical investigations which may reveal the presence of potential risk factors for crashing. As such, culpability analysis is well suited to the study of transient exposures, as related to crash risk, that are typically difficult to determine in a valid control population of non-crash involved drivers. For example, when studying drug use in relation to driving, it is a challenge to measure the actual rate of drug use in non-crash involved drivers because the refusal rate for drug testing in roadside controls typically exceeds the proportion of drivers who test positive for drugs, severely limiting data interpretation. Culpability analysis can overcome this problem when there are legal or medical protocols in place to determine drug use of crash involved drivers. The study of cellphone use while driving is another situation where obtaining good data in comparable non-crash involved drivers (or during a comparable ‘control driving period’ if using the case-crossover methodology) is a particular challenge. Our study employed culpability analysis to study the risk of crashes associated with cellphones for this very reason. Our findings were consistent with those derived using alternative study designs and support the growing understanding of the risks of driving while using cellphones. The term ‘culpability’ when used in the assessmentof crashes is drawn from its historical application as a means for determining legal fault; however, modern applications of culpability analysis have moved beyond this perspective to assess responsibility based upon a comprehensive set of indicators observed from the crash. Modern culpability studies, as well as considering whether actions of the index driver contributed to the crash, also look for other contributory factors such as road type, driving conditions, vehicle condition, contribution from other parties, crash type and difficulty of the task being performed. When actions of the index driver did not contribute to the crash and other factors did contribute, then the index driver is deemed ‘non-culpable’. It is the non-culpable drivers that are of greatest interest in a culpability analysis. As summarized by Wahlberg, culpability analysis is based on the assumption that drivers found non-culpable after a car crash represent a random sample of the general driving population that was ‘selected’ to crash by circumstances beyond their control and therefore have the same risk factor profile of other drivers on the road at the same time [odds ratio (OR)1⁄4 1.00]. If this ‘randomness assumption’ is met, then the risk estimate derived from a culpability analysis would be expected to be similar to that from a standard case-control study. To explain the assertion that culpability studies cannot help us understand crash risk due to cellphone use, Sanghavi presents a hypothetical scenario whereby cellphones prevent crashes and have a stronger protective effect during bad driving conditions. The author claims that this scenario could account for our findings and explains this by speaking of ‘culpable conditions’. We would first like to point out that Sanghavi’s hypothetical scenario where cellphones prevent crashes is inconsistent with extensive experimental research that demonstrates that cellphones impair concentration, reaction time and other skills required for safe driving. Leaving this Published by Oxford University Press on behalf of the International Epidemiological Association

Development and validation of a crash culpability scoring tool.

Objective: Several traffic safety research techniques require researchers to separate crash-involved drivers into culpable and nonculpable. Nonculpable drivers are assumed to be randomly involved in crashes by external factors and to approximate a noncollision control population. If this is true, factors that increase crash risk should be found more often in culpable than in nonculpable drivers. Though a culpability scoring tool has been developed for research purposes, that tool does not adequately address winter driving conditions (Robertson and Drummer 1994). Moreover, traditional culpability scoring requires assessors to read and score individual collision reports. The purpose of this study is to develop and validate an automated, rule-based Canadian culpability scoring tool that is capable of rapidly scoring police crash reports from large administrative datasets. Methods: We used an iterative approach to develop and validate our tool. First, the Robertson-Drummer culpability scoring tool was modified to include the extensive police report data collected in the British Columbia Traffic Accident System (TAS) and to account for winter driving conditions. This was done in consultation with traffic safety experts. The scoring tool was automated, employing a rule-based decision model that avoids interpretation of free-text reports. The scoring tool was applied to 73 collisions (134 drivers). Two experts also reviewed these collisions and determined the culpability of each driver. Discrepant cases were discussed to understand why the scoring tool differed from the expert assessment and the scoring tool was modified accordingly. The final tool was compared with expert assessment on another sample of 96 crashes. The tool was also applied to a sample of 2086 crash-involved drivers with known blood alcohol concentrations (BACs) and the adjusted odds of culpability were calculated for several BAC ranges. Results: The final scoring tool included 7 factors and had content validity for traffic safety experts. It had excellent agreement with expert scoring on the first set of collisions (kappa = 0.83, 95% confidence interval [CI]: 0.75–0.91) and on the second set (kappa = 0.84, 95% CI: 0.77–0.92). When applied to crash-involved drivers with known BAC levels, the scoring tool exhibited predictive validity: the odds of culpability increased with higher BACs, consistent with the known dose effect of BAC on crash risk. Conclusions: We have developed an automated culpability scoring tool contextualized to Canadian driving conditions. This tool will allow road safety researchers to assess collision responsibility in large administrative data sets derived from police reports.

The Association between Regional Environmental Factors and Road Trauma Rates: A Geospatial Analysis of 10 Years of Road Traffic Crashes in British Columbia, Canada

Background British Columbia, Canada is a geographically large jurisdiction with varied environmental and socio-cultural contexts. This cross-sectional study examined variation in motor vehicle crash rates across 100 police patrols to investigate the association of crashes with key explanatory factors. Methods Eleven crash outcomes (total crashes, injury crashes, fatal crashes, speed related fatal crashes, total fatalities, single-vehicle night-time crashes, rear-end collisions, and collisions involving heavy vehicles, pedestrians, cyclists, or motorcyclists) were identified from police collision reports and insurance claims and mapped to police patrols. Six potential explanatory factors (intensity of traffic law enforcement, speed limits, climate, remoteness, socio-economic factors, and alcohol consumption) were also mapped to police patrols. We then studied the association between crashes and explanatory factors using negative binomial models with crash count per patrol as the response variable and explanatory factors as covariates. Results Between 2003 and 2012 there were 1,434,239 insurance claim collisions, 386,326 police reported crashes, and 3,404 fatal crashes. Across police patrols, there was marked variation in per capita crash rate and in potential explanatory factors. Several factors were associated with crash rates. Percent roads with speed limits ≤ 60 km/hr was positively associated with total crashes, injury crashes, rear end collisions, and collisions involving pedestrians, cyclists, and heavy vehicles; and negatively associated with single vehicle night-time crashes, fatal crashes, fatal speeding crashes, and total fatalities. Higher winter temperature was associated with lower rates of overall collisions, single vehicle night-time collisions, collisions involving heavy vehicles, and total fatalities. Lower socio-economic status was associated with higher rates of injury collisions, pedestrian collisions, fatal speeding collisions, and fatal collisions. Regions with dedicated traffic officers had fewer fatal crashes and fewer fatal speed related crashes but more rear end crashes and more crashes involving cyclists or pedestrians. The number of traffic citations per 1000 drivers was positively associated with total crashes, fatal crashes, total fatalities, fatal speeding crashes, injury crashes, single vehicle night-time crashes, and heavy vehicle crashes. Possible explanations for these associations are discussed. Conclusions There is wide variation in per capita rates of motor vehicle crashes across BC police patrols. Some variation is explained by factors such as climate, road type, remoteness, socioeconomic variables, and enforcement intensity. The ability of explanatory factors to predict crash rates would be improved if considered with local traffic volume by all travel modes.

Risk Factors for Subsequent Impaired Driving by Injured Passengers

Objectives: The purpose of this study was to evaluate the rate of, and risk factors for, subsequent impaired driving activity (IDA) in a cohort of injured passengers who were treated for injuries in a Canadian trauma center. Methods: We studied adult passengers who were occupants in vehicles involved in motor vehicle crashes (MVCs) and either included in the British Columbia (BC) trauma registry (January 1, 1992–December 31, 2004) or treated in the emergency department (ED) of Vancouver General Hospital (VGH; January 1, 1999–December 31, 2003). Passengers were linked to their drivers license and hence to their driving record using personal health number and demographic information. Injured passengers were stratified into 3 groups based on their blood alcohol concentration (BAC) at time of ED presentation: group 1: BAC = 0, group 2: 0 < BAC ≤ 17.3 mM (0.08%), group 3: BAC > 17.3 mM (0.08%). Two outcome variables were studied: involvement in a subsequent IDA and time to their first subsequent IDA. IDA was defined as a criminal code conviction for impaired driving, a 24-h or 90-day license suspension for impaired driving, and/or involvement in an MVC where police cited alcohol as a factor. Time to first IDA following the index event among passenger BAC groups was compared with Kaplan-Meier survival analysis. Cox proportional hazards models were employed to examine the effect of various potential risk factors on time to engage in first IDA. Results: Injured passengers with any BAC at the time of ED visit were more likely to engage in IDA and had their first IDA sooner after the index event than those with zero BAC. Among this cohort of injured passengers, 12.1 percent with BAC = 0, 29.9 percent with 0 < BAC ≤ 17.3 mM (0.08%), and 37.8 percent with a BAC > 17.3 mM (0.08%) engaged in IDA. Compared to passengers with BAC = 0, group 3 passengers and group 2 passengers were 2.06 times and 1.79 times more likely to engage in future IDA. Twenty-five percent of injured passengers engaged their first IDA by 57 and 38 months in groups 2 and 3, respectively. Previous IDA and being male were also significant risk factors for future IDA. Those with a history of IDA before the index event were 2.37 times more likely to engage in subsequent IDA. Conclusions: Injured alcohol-impaired passengers are at high risk for IDA and should be included in impaired driving prevention programs.