Factors affecting the severity of work related traffic crashes in drivers receiving a worker's compensation claim

Aim

To examine factors that contribute to the severity of work related crashes in New South Wales, Australia.

Methods

Workers’ Compensation data was linked to police crash records for the period 1998-2002. Multivariate analysis was carried out to assess the relationship between relevant risk factors and the severity of injury (permanent disability or death) in drivers who had received a claim for a work related crash.

Results

Age, gender, occupation, duty status, vehicle type, licence status, fatigue, speeding and location of the crash were independently associated with the severity of the crash. Drivers aged 65 years and older were nearly twice (OR: 1.824, 95% CI: 1.106-3.007) as likely to be permanently injured or die as a result of a work related crash compared to the younger age group (15-24 years old). The risk to older drivers was even higher in crashes occurring while on duty. Drivers involved in traffic crashes while commuting were more likely to be severely injured (OR: 1.28, CI: 1.15-1.42) than those on duty. Compared to car drivers, taxi drivers were more than twice (OR: 2.38, CI: 1.726-3.296) as likely to be severely injured.

Conclusions

The findings contribute to bridging the gap in knowledge in the area of work related crashes and highlight the higher risk of permanent disability and death in older drivers, taxi drivers and commuters.     

Risk and type of crash among young drivers by rurality of residence: Findings from the DRIVE Study

Background

Most previous literature on urban/rural differences in road crashes has a primary focus on severe injuries or deaths, which may be largely explained by variations of medical resources. Little has been reported on police-reported crashes by geographical location, or crash type and severity, especially among young drivers.

Methods

DRIVE is a prospective cohort study of 20,822 drivers aged 17-24 in NSW, Australia. Information on risk factors was collected via online questionnaire and subsequently linked to police-reported crashes. Poisson regression was used to analyse risk of various crash types by three levels of rurality of residence: urban, regional (country towns and surrounds) and rural.

Results

Compared to urban drivers, risk of crash decreased with increasing rurality (regional adjusted RR: 0.7, 95% CI 0.6-0.9; rural adjusted RR: 0.5, 95% CI 0.3-0.7). Among those who crashed, risk of injurious crash did not differ by geographic location; however, regional and rural drivers had significantly higher risk of a single versus multiple vehicle crash (regional adjusted RR 1.8, 95% CI 1.3-2.5; rural adjusted RR: 2.0, 95% CI 1.1-3.6), which was explained by speeding involvement and road alignment at the time or site of crash.

Conclusions

Although young urban drivers have a higher crash risk overall, rural and regional residents have increased risk of a single vehicle crash. Interventions to reduce single vehicle crashes should aim to address key issues affecting such crashes, including speeding and specific aspects of road geometry.     

The effect of helmet use on injury severity and crash circumstances in skiers and snowboarders

The aim of this study was to examine the effect of helmet use on non-head-neck injury severity and crash circumstances in skiers and snowboarders. We used a matched case-control study over the November 2001 to April 2002 winter season. 3295 of 4667 injured skiers and snowboarders reporting to the ski patrol at 19 areas in Quebec with non-head, non-neck injuries agreed to participate. Cases included those evacuated by ambulance, admitted to hospital, with restriction of normal daily activities (NDAs) >6 days, with non-helmet equipment damage, fast self-reported speed, participating on a more difficult run than usual, and jumping-related injury. Controls were injured participants without severe injuries or high-energy crash circumstances and were matched to cases on ski area, activity, day, age, and sex. Conditional logistic regression was used to relate each outcome to helmet use. There was no evidence that helmet use increased the risk of severe injury or high-energy crash circumstances. The results suggest that helmet use in skiing and snowboarding is not associated with riskier activities that lead to non-head-neck injuries.     

Do bicycle safety helmets reduce severity of head injury in real crashes?

In the past, evaluation of helmet efficacy has been based on laboratory tests of limited relevance to real crashes. In the present study 894 South Australian bicycling enthusiasts returned mail questionnaires about their most recent bicycle crash and their helmet use at the time. 197 bicyclists reported a crash within the past five years in which they had struck their head or helmet. Helmet status at the time of the crash was reported as: no helmet used (n = 75), hairnet-style helmet (n = 69), hard-shell with soft or no liner (n = 37), or hard-shell helmet with stiff liner (n = 16). Analysis of the crude, unadjusted data showed a statistically significant association between helmet use and reduced severity of head injury. The association persisted after adjustment for age and sex of rider, and severity of crash forces. Using an unpublished method developed by Somers, it was estimated that the risk of death from head injury was considerably reduced for helmeted relative to unhelmeted bicyclists, depending on helmet type.     

Incidence and characteristics of school bus crashes and injuries

Objective

Studies of school bus crashes have focused on the biomechanics of catastrophic collisions, with very few examining crash incidence.

Methods

Crashes in the state of Iowa were examined from January 2002 through December 2005. School bus crashes were identified through the Iowa Crash Data, a comprehensive database of all reported crashes in the State of Iowa. School bus mileage data were provided by the Iowa Department of Education. School bus crash, fatality, and injury rates were calculated and differences in crash and injury characteristics between school buses and other vehicles were examined.

Results

The school bus crash, fatality and non-fatal injury rates were 320.7, 0.4 and 13.6 per 100 million bus miles travelled, respectively. School bus crash fatality and injury rates were 3.5 and 5.4 times lower than overall all vehicle crash fatality and injury rates, respectively. Drivers of other vehicles were more likely to have caused the crash than the bus driver (P < 0.001).

Conclusions

School buses experience low crash rates, and the majority of crashes do not lead to injury. Buses are among the safest forms of road transportation, and efforts to educate drivers of other vehicles may help reduce crashes with buses.     

Investigation of pulmonary contusion extent and its correlation to crash,occupant, and injury characteristics in motor vehicle crashes

Background

Pulmonary contusion (PC) is a leading injury in blunt chest trauma and is most commonly caused by motor vehicle crashes (MVC). To improve understanding of the relationship between insult and outcome, this study relates PC severity to crash, occupant, and injury parameters in MVCs.

Methods

Twenty-nine subjects with PC were selected from the Crash Injury Research and Engineering Network (CIREN) database, which contains detailed crash and medical information on MVC occupants. Computed tomography scans of these subjects were segmented using a semi-automated protocol to quantify the volumetric percentage of injured tissue in each lung. Techniques were used to quantify the geometry and location of PC, as well as the location of rib fractures. Injury extent including percent PC volume and the number of rib fractures was analyzed and its relation to crash and occupant characteristics was explored.

Results

Frontal and near-side crashes composed 72% of the dataset and the near-side door was the component most often associated with PC causation. The number of rib fractures increased with age and fracture patterns varied with crash type. In near-side crashes, occupant weight and BMI were positively correlated with percent PC volume and the number of rib fractures, and the impact severity was positively correlated with percent PC volume in the lung nearest the impact.

Conclusions

This study quantified PC morphology in 29 MVC occupants and examined the relationship between injury severity and crash and occupant parameters to better characterize the mechanism of injury. The results of this study may contribute to the prevention, mitigation, and treatment of PC.     

Comparing the effects of age,BMI and gender on severe injury (AIS 3+) in motor-vehicle crashes

Background

The effects of age, body mass index (BMI) and gender on motor vehicle crash (MVC) injuries are not well understood and current prevention efforts do not effectively address variability in occupant characteristics.

Objectives

(1) Characterize the effects of age, BMI and gender on serious-to-fatal MVC injury. (2) Identify the crash modes and body regions where the effects of occupant characteristics on the numbers of occupants with injury is largest, and thereby aid in prioritizing the need for human surrogates that represent different types of occupant characteristics and adaptive restraint systems that consider these characteristics.

Methods

Multivariate logistic regression was used to model the effects of occupant characteristics (age, BMI, gender), vehicle and crash characteristics on serious-to-fatal injuries (AIS 3+) by body region and crash mode using the 2000–2010 National Automotive Sampling System (NASS-CDS) dataset. Logistic regression models were applied to weighted crash data to estimate the change in the number of annual injured occupants with AIS 3+ injury that would occur if occupant characteristics were limited to their 5th percentiles (age ≤ 17 years old, BMI ≤ 19 kg/m²) or male gender.

Results

Limiting age was associated with a decrease in the total number of occupants with head [8396, 95% CI 6871–9070] and thorax injuries [17,961, 95% CI 15,960–18,859] across all crash modes, decreased occupants with spine [3843, 95% CI 3065–4242] and upper extremity [3578, 95% CI 1402–4439] injuries in frontal and rollover crashes and decreased abdominal [1368, 95% CI 1062–1417] and lower extremity [4584, 95% CI 4012–4995] injuries in frontal impacts. The age effect was modulated by gender with older females more likely to have thorax and upper extremity injuries than older males. Limiting BMI was associated with 2069 [95% CI 1107–2775] fewer thorax injuries in nearside crashes, and 5304 [95% CI 4279–5688] fewer lower extremity injuries in frontal crashes. Setting gender to male resulted in fewer occupants with head injuries in farside crashes [1999, 95% CI 844–2685] and fewer thorax [5618, 95% CI 4212–6272], upper [3804, 95% CI 1781–4803] and lower extremity [2791, 95% CI 2216–3256] injuries in frontal crashes. Results indicate that age provides the greater relative contribution to injury when compared to gender and BMI, especially for thorax and head injuries.

Conclusions

Restraint systems that account for the differential injury risks associated with age, BMI and gender could have a meaningful effect on injury in motor-vehicle crashes. Computational models of humans that represent older, high BMI, and female occupants are needed for use in simulations of particular types of crashes to develop these restraint systems.     

Risk factors for causing road crashes involving cyclists: An application of a quasi-induced exposure method

A quasi-induced exposure approach was applied to the Spanish Register of Traffic Crashes to identify driver- and vehicle-related factors associated with the risk of causing a road crash involving a cyclist in Spain from 1993 to 2009. We analyzed 19,007 collisions between a bicycle and another vehicle in which only one of the drivers committed an infraction, and 13,540 records that included the group of non-infractor cyclists in the above collisions plus cyclists involved in single-bicycle crashes. Adjusted odds ratios were calculated for being responsible for each type of crash for each factor considered. Age from 10 to 19 years, male sex, alcohol or drug consumption and non-helmet use were cyclist-related variables associated with a higher risk of crash, whereas cycling more than 1 h increased only the risk of single crashes. Bicycles with brake defects and ridden by two occupants were also at higher risk of involvement in a crash, whereas light defects were associated only with collisions with another vehicle. For drivers of the other vehicle, age more than 60 years, alcohol, not using safety devices and nonprofessional drivers were at higher risk. The risk of colliding with a bicycle was higher for mopeds than for passenger cars.     

The relationship between body weight and risk of death and serious injury in motor vehicle crashes

We sought to investigate the effect of increased body weight on the risk of death and serious injury to occupants in motor vehicle crashes. We employed a retrospective cohort study design utilizing data from the National Automotive Sampling System, Crashworthiness Data System (CDS), 1993-1996. Subjects in the study included occupants involved in tow-away crashes of passenger cars, light trucks, vans and sport utility vehicles. Two outcomes were analyzed: death within 30 days of the crash and injury severity score (ISS). Two exposures were considered: occupant body weight and body mass index (BMI; kg/m2). Occupant weight was available on 27263 subjects (76%) in the CDS database. Mortality was 0.67%. Increased body weight was associated with increased risk of mortality and increased risk of severe injury. The odds ratio for death was 1.013 (95% CI: 1.007, 1.018) for each kilogram increase in body weight. The odds ratio for sustaining an injury with ISS > or = 9 was 1.008 (95% CI: 1.004, 1.011) for each kilogram increase in body weight. After adjustment for potentially confounding variables (age, gender, seatbelt use, seat position and vehicle curbweight), the significant relationship between occupant weight and mortality persisted. After adjustment, the relationship between occupant weight and ISS was present, although less marked. Similar trends were found when BMI was analyzed as the exposure. In conclusion, increased occupant body weight is associated with increased mortality in automobile crashes. This is probably due in part to increased co-morbid factors in the more overweight occupants. However, it is possibly also due to an increased severity of injury in these occupants. These findings may have implications for vehicle safety design, as well as for transport safety policy.     

Association of cyclists’ age and sex with risk of involvement in a crash before and after adjustment for cycling exposure

This study aimed to estimate the association of cyclists’ age and sex with the risk of being involved in a crash with and without adjustment for their amount of exposure. We used the distribution of the entire population and cyclists (total and non-responsible) involved in road crashes in Spain between 1993 and 2009 held by the Spanish National Institute of Statistics and the Spanish General Traffic Directorate to calculate rates of exposure and involvement in a crash. Males aged 45–49 years were used as the reference category to obtain exposure rate ratios (ERR) and unadjusted crash rate ratios (URR). We then used these values in decomposition analysis to calculate crash rate ratios adjusted for exposure (ARR). The pattern of ARR was substantially different from URR. In both sexes the highest values were observed in the youngest age groups, and the values decreased as age increased except for a slight increase in the oldest age groups. In males, a slight increase in the lowest and highest age categories was observed for crashes resulting in severe injury or death, and a decrease was observed for the youngest cyclists who were wearing a helmet. The large differences between age and sex groups in the risk of involvement in a cycling crash are strongly dependent on differences in their exposure rates. Taking exposure rates into account, cyclists younger than 30 years and older than 65 years of age had the highest risk of being involved in a crash.     

Comparison of roadside crash injury metrics using event data recorders

The occupant impact velocity (OIV) and acceleration severity index (ASI) are competing measures of crash severity used to assess occupant injury risk in full-scale crash tests involving roadside safety hardware, e.g. guardrail. Delta-V, or the maximum change in vehicle velocity, is the traditional metric of crash severity for real world crashes. This study compares the ability of the OIV, ASI, and delta-V to discriminate between serious and non-serious occupant injury in real world frontal collisions. Vehicle kinematics data from event data recorders (EDRs) were matched with detailed occupant injury information for 180 real world crashes. Cumulative probability of injury risk curves were generated using binary logistic regression for belted and unbelted data subsets. By comparing the available fit statistics and performing a separate ROC curve analysis, the more computationally intensive OIV and ASI were found to offer no significant predictive advantage over the simpler delta-V.     

Rear seat safety: Variation in protection by occupant,crash and vehicle characteristics

Objectives

Current information on the safety of rear row occupants of all ages is needed to inform further advances in rear seat restraint system design and testing. The objectives of this study were to describe characteristics of occupants in the front and rear rows of model year 2000 and newer vehicles involved in crashes and determine the risk of serious injury for restrained crash-involved rear row occupants and the relative risk of fatal injury for restrained rear row vs. front passenger seat occupants by age group, impact direction, and vehicle model year.

Method

Data from the National Automotive Sampling System Crashworthiness Data System (NASS-CDS) and Fatality Analysis Reporting System (FARS) were queried for all crashes during 2007–2012 involving model year 2000 and newer passenger vehicles. Data from NASS-CDS were used to describe characteristics of occupants in the front and rear rows and to determine the risk of serious injury (AIS 3+) for restrained rear row occupants by occupant age, vehicle model year, and impact direction. Using a combined data set containing data on fatalities from FARS and estimates of the total population of occupants in crashes from NASS-CDS, logistic regression modeling was used to compute the relative risk (RR) of death for restrained occupants in the rear vs. front passenger seat by occupant age, impact direction, and vehicle model year.

Results

Among all vehicle occupants in tow-away crashes during 2007–2012, 12.3% were in the rear row where the overall risk of serious injury was 1.3%. Among restrained rear row occupants, the risk of serious injury varied by occupant age, with older adults at the highest risk of serious injury (2.9%); by impact direction, with rollover crashes associated with the highest risk (1.5%); and by vehicle model year, with model year 2007 and newer vehicles having the lowest risk of serious injury (0.3%). Relative risk of death was lower for restrained children up to age 8 in the rear compared with passengers in the right front seat (RR = 0.27, 95% CI 0.12–0.58 for 0–3 years, RR = 0.55, 95% CI 0.30–0.98 for 4–8 years) but was higher for restrained 9–12-year-old children (RR = 1.83, 95% CI 1.18–2.84). There was no evidence for a difference in risk of death in the rear vs. front seat for occupants ages 13-54, but there was some evidence for an increased relative risk of death for adults age 55 and older in the rear vs. passengers in the right front seat (RR = 1.41, 95% CI 0.94–2.13), though we could not exclude the possibility of no difference. After controlling for occupant age and gender, the relative risk of death for restrained rear row occupants was significantly higher than that of front seat occupants in model year 2007 and newer vehicles and significantly higher in rear and right side impact crashes.

Conclusions

Results of this study extend prior research on the relative safety of the rear seat compared with the front by examining a more contemporary fleet of vehicles. The rear row is primarily occupied by children and adolescents, but the variable relative risk of death in the rear compared with the front seat for occupants of different age groups highlights the challenges in providing optimal protection to a wide range of rear seat occupants. Findings of an elevated risk of death for rear row occupants, as compared with front row passengers, in the newest model year vehicles provides further evidence that rear seat safety is not keeping pace with advances in the front seat.     

Relative risk of death from ejection by crash type and crash mode

In virtually all circumstances, the chance of survival in a crash is much greater if the occupant is not ejected from the vehicle. Several estimates of the increased risk of death as a result of ejection (ranging from 2.5 to 25) have been made, but none were specific to the crash mode and most did not control for crash severity. The current study examined the relative risk of fatality due to ejection, by crash type and crash mode, using the Fatal Accident Reporting System data from the years 1982 through 1986. Crash type was defined as either single vehicle or multivehicle and crash mode included rollover, nonrollover, and/or direction of impact. Crash severity was controlled for using a paired comparison method of analysis. Both crash type and crash mode were found to have substantial effects on the relative risk of death due to ejection. In addition, risk differences across seating position exist. Depending on crash mode or type, the risks ranged from about 1.5 to 8. Single-vehicle rollover crashes have the highest increased risk of death due to ejection: about eightfold for the driver and sevenfold for the right front passenger.     

Injury thresholds after motor vehicle crash—Important factors for patient triage and vehicle design

Introduction

The Committee on Trauma recommends that older motor vehicle crash (MVC) victims or victims of crashes with significant vehicle intrusion of more than 12 in. be transferred to a trauma center since those older than 55 have an increased risk of death after injury. Yet, the precise injury thresholds as they relate to age, gender and velocity remain ill-defined. To maintain a low rate of under triage, reliable methods to identify patients at moderate injury risk are needed. We therefore characterized the likelihood of moderate to severe injury in MVC victims to determine the influence of age, gender and velocity.

Methods

An analysis of drivers from the National Automotive Sampling System (1993-2001) was performed. Weighted logistic regression models were developed to predict the probability of head, leg, and torso injuries as a function of vehicle speed, age, and gender while controlling for confounders. A 10% probability of injury threshold was set and differences in velocity, gender and age were identified in terms of reaching this probability of injury threshold.

Results

The analysis yielded 56,459 drivers which is equivalent to a population of 28,877,696 drivers nationwide. Restraint use, steering away prior to impact, breaking maneuver, gender, delta velocity, driver height and age were independent predictors of injury. Women had a higher velocity injury threshold than men for the 10% probability of injury cut-off to the torso or head which disappeared with increasing age. Conversely, men had a higher velocity injury threshold than women for the 10% probability of injury cut-off to the extremity which persisted even in older victims.

Conclusions

Our data indicate that age and gender must be considered in addition to crash velocity when making triage decisions. Furthermore, Federal Motor Vehicle Safety Standards may need to be modified to address the increased risk of injury among older adults at lower velocities given the increasing number of elderly drivers in the US.     

Comparing the cost of alcohol-related traffic crashes in rural and urban environments

Context

Existing studies have identified that, although to a lesser extent than individual factors such as males and young people, rural (compared to urban) communities represent a disproportionately high-risk of alcohol-related traffic crashes (ARTCs). To date, however, few studies have attempted to apply different costs to alcohol crashes of different severity, to provide more precise, and practically useful, data on which to base public health policy and intervention decisions.

Objective

The aim of this study is to quantify the per capita prevalence and differential costs of alcohol crashes of different levels of severity to determine the extent to which urban and rural geographical areas may differ in the costs attributable to ARTCs.

Design

A cross-sectional analysis of alcohol-related traffic crash and costs data from 2001 to 2007.

Setting and participants

Data from New South Wales, Australia.

Main outcome measures

Modified routinely collected traffic accident data to which costs relevant to alcohol crashes of different severity are applied.

Results

Although the rate per 10,000 population of alcohol-related crashes is 1.5 times higher in rural, relative to urban, communities, the attributable cost is four times higher, which largely reflects that rural alcohol-fatalities are seven to eight times more prevalent and costly.

Conclusions

Given that per capita alcohol-related fatal crashes in rural areas account for a disproportionately large proportion of the harms and costs associated with alcohol-related traffic crashes, the cost-effectiveness of public health interventions and public policy initiatives should consider the relative extent of ARTC-harm in rural versus urban communities.     

Crash risk factors related to individuals sustaining and drivers following traumatic brain injuries

Objective

Some crashes result in drivers experiencing (or sustaining) a traumatic brain injury (TBI) while other crashes involve drivers that have already experienced a TBI. The objective of this study is to examine the factors that influence these two TBI crash groups.

Methods

Data from the Iowa Department of Public Health's Brain Injury Registry and Department of Transportation's crash records were linked together and used in logistic regression models to predict the likelihood of a driver sustaining a TBI in a crash and those who drive after a TBI.

Results

Between 2001 and 2006, there were 2382 crashes in which an individual sustained a TBI. As expected, a higher likelihood of sustaining a TBI was observed for motorcycle drivers who did not wear a helmet and in crashes that resulted in total or disabling vehicle damage. Focusing specifically on the post-TBI drivers (and not occupants), 1583 were involved in crashes. These post-TBI drivers were less likely to wear seatbelts or have passengers in the vehicle at the time of the crash, and were more likely to crash at night. Post-TBI drivers were also involved in significantly more multiple crashes (about 14%) when compared to drivers who have not experienced a TBI (about 10%) during the study period. When controlling for gender, date of injury, and severity of TBI (using Glasgow Coma Scale), individuals that sustained a TBI when they were younger were more likely to be involved in multiple crashes.

Conclusions

Different factors influence the crash likelihood for those that sustain a TBI in a crash and those that crash following a TBI. In general, post-TBI drivers have a higher occurrence of multiple crashes and this should be further explored to guide driver rehabilitation, evaluation, and training.     

Risk factors for severe injury in cyclists involved in traffic crashes in Victoria,Australia

This study examines the impact of cyclist, road and crash characteristics on the injury severity of cyclists involved in traffic crashes reported to the police in Victoria, Australia between 2004 and 2008. Logistic regression analysis was carried out to identify predictors of severe injury (serious injury and fatality) in cyclist crashes reported to the police. There were 6432 cyclist crashes reported to the police in Victoria between 2004 and 2008 with 2181 (33.9%) resulting in severe injury of the cyclist involved. The multivariate analysis found that factors that increase the risk of severe injury in cyclists involved in traffic crashes were age (50 years and older), not wearing a helmet, riding in the dark on unlit roads, riding on roads zoned 70 km/h or above, on curved sections of the road, in rural locations and being involved in head-on collisions as well as off path crashes, which include losing control of vehicle, and on path crashes which include striking the door of a parked vehicle. While this study did not test effectiveness of preventative measures, policy makers should consider implementation of programs that address these risk factors including helmet programs and environmental modifications such as speed reduction on roads that are frequented by cyclists.     

Double pair comparison--a new method to determine how occupant characteristics affect fatality risk in traffic crashes

A new method to determine how occupant characteristics affect fatality risk in traffic crashes is developed. The method, which uses data from the Fatal Accident Reporting System (FARS), focuses on two occupants, a "subject" occupant and an "other" occupant. The probabilities of a fatality to the subject occupant when that occupant has one of two characteristics are compared. The other occupant serves essentially a normalizing, or exposure estimating, role. The method uses only fatality frequency data--no external exposure information is required, and it is relatively free from uncertain assumptions. It has wide applicability; examples of potential applications include investigating car occupant fatality risk as a function of sex, age, alcohol use or motorcyclist fatality risk as a function of helmet use. The first application is to determining the effectiveness of safety belts in preventing car occupant fatalities, as described in the paper following this paper.     

Declines in fatal crashes of older drivers: changes in crash risk and survivability

Objectives

Previous research has found that older driver fatal crash involvement rates per licensed driver declined substantially in the United States during 1997–2006 and declined much faster than the rate for middle-age drivers. The current study examined whether the larger-than-expected decline for older drivers extended to nonfatal crashes and whether the decline in fatal crash risk reflects lower likelihood of crashing or an improvement in survivability of the crashes that occur.

Methods

Trends in the rates of passenger vehicle crash involvements per 100,000 licensed drivers for drivers 70 and older (older drivers) were compared with trends for drivers ages 35–54 (middle-age drivers). Fatal crash information was obtained from the Fatality Analysis Reporting System for years 1997–2008, and nonfatal crash information was obtained from 13 states with good reporting information for years 1997–2005. Analysis of covariance models compared trends in annual crash rates for older drivers relative to rates for middle-age drivers. Differences in crash survivability were measured in terms of the odds of fatality given a crash each year, and the historical trends for older versus middle-age drivers were compared.

Results

Fatal crash involvement rates declined for older and middle-age drivers during 1997–2008 (1997–2005 for the 13 state subsample), but the decline for drivers 70 and older far exceeded the decline for drivers ages 35–54 (37 versus 23 percent, nationally; 22 versus 1 percent, 13 states). Nonfatal injury crash involvement rates showed similarly larger-than-expected declines for older drivers in the 13 state subsample, but the differences were smaller and not statistically significant (27 percent reduction for older drivers versus 16 percent for middle-age drivers). Property-damage-only crash involvement rates declined for older drivers (10 percent) but increased for middle-age drivers (1 percent). In 1997, older drivers were 3.5 times more likely than middle-age drivers to die in police-reported crashes (6.2 versus 1.8 deaths per 1000 crashes), but this difference was reduced during the 9-year study period to 2.9 times, as the rate of older drivers dying in a crash declined (5.5 deaths per 1000 crashes in 2005) and the death risk remained relatively stable for middle-age drivers.

Conclusions

Contrary to expectations based on increased licensure and travel by older drivers, their fatal crash risk has declined during the past decade and has declined at a faster rate than for middle-age drivers. The decreased risk for older drivers appears to extend not only to nonfatal injury crashes but also to property-damage-only crashes, at least as reported to police in the 13 states included in the nonfatal injury analysis. Although insurance collision data suggest that overall crash risk of older drivers may not be changing relative to middle-age drivers, the current analysis indicates that the reduced fatality risk of older drivers reflects both less likelihood of being involved in a police-reported crash and greater likelihood that they will survive when they do crash.     

Comparison of two methods to assess the effect of age and sex on the risk of car crashes

Background

This study was designed to compare two methods (direct measurement of exposure and quasi-induced exposure) for assessing the effect of age and sex on the risk of being involved in a car crash in Spain.

Methods

Spanish crash rates (per 10,000,000 driver-km) for age and sex groups of drivers aged 18–64 years old were obtained for 2004–2007, using information from the Spanish General Traffic Office (census of reported car crashes) and the Spanish Household Survey on Alcohol and Drugs (estimate of the mean km driven for each car driver). The rate ratios estimated by direct exposure estimates were compared to those obtained with the quasi-induced exposure method, which compares the age and sex of responsible and non-responsible drivers involved in the same clean collision (in which only one of the drivers committed a driving infraction).

Results

Both methods detected an increased risk of involvement in a crash for the youngest (18–20 years) and the oldest drivers (60–64 years), compared to middle-aged drivers (45–49 years). However, the rate ratios obtained with the quasi-induced method for the youngest group (2.0 for men, 1.6 for women) were much lower than those obtained with crash rates (13.4 for men, 5.7 for women). Both methods detected a similar increase in the risk of involvement of male drivers compared to women in the youngest age group. This excess risk for men was maintained with increasing age up to 45–49 years when the quasi-induced method was used. However, direct comparisons of crash rates revealed an increased risk of involvement in women compared to men of the same age from 25–29 years onward.

Conclusions

Both direct measurement of driving exposure and the quasi-induced exposure method detected some well-known patterns of risk associated with driver's age and sex. However, factors that could explain important differences between the two methods deserve attention, especially those related with the excess risk for the youngest drivers as well as sex-related risk.