Characteristics of Crashes With Farm Equipment That Increase Potential for Injury

CONTEXT: Crash fatality and injury rates are higher on rural roadways than other roadway types. Although slow-moving farm vehicles and equipment are risk factors on rural roads, little is known about the characteristics of crashes with farm vehicles/equipment. PURPOSE: To describe crashes and injuries for the drivers of farm vehicles/equipment and non-farm vehicles involved in an injury crash. Passengers are not included in this analysis. METHODS: Injury crashes were included that involved a farm vehicle/equipment and at least one non-farm vehicle reported in Iowa Department of Transportation crash data from 1995 to 2004. Odds ratios were calculated through logistic regression to identify increased odds for injury among drivers of non-farm vehicles and farm vehicles/equipment. We examined frequently occurring crash characteristics to identify crash scenarios leading to the highest odds for injury. FINDINGS: Non-farm vehicle drivers were 5.23 times more likely to be injured than farm vehicle/equipment drivers (95% CI = 4.12-6.46). The absence of restraint use was a significant predictor of injury for both farm vehicle/equipment drivers (OR = 2.85; 95% CI = 1.14-7.13) and non-farm vehicle drivers (OR = 2.53; 95% CI = 1.54-4.15). Crash characteristics increasing the odds of injury for non-farm vehicle drivers included speeding, passing the farm vehicle/equipment, driving on a county road, having a frontal impact collision, and crashing in darkness. Ejection was the strongest predictor of injury for the farm vehicle/equipment driver. CONCLUSION: Non-farm vehicle drivers were much more likely to be injured than farm vehicle/equipment drivers, suggesting that farm vehicle/equipment crash prevention should be a priority for all rural road users. Prevention strategies that reduce motor vehicle speed, assist in safe passing, increase seat belt use, and increase conspicuousness of the farm vehicle/equipment are suggested.     

State motor vehicle laws and older drivers

After teenage males, elderly individuals have the highest per capita motor vehicle fatality rate in the United States. Surprisingly, there has been only limited work examining the effect of state motor vehicle laws on older driver fatalities. This paper uses state-level data from the 1985-2000 Fatality Analysis Reporting System to examine the effects of changes in state laws dealing with license renewal, seatbelt use, speed limits, and driving while intoxicated on fatalities among drivers and others aged 65 and over. Negative binomial regressions are estimated using alternatively state and year fixed effects, or age and year fixed effects. In-person license renewal reduced fatalities among the oldest drivers, but vision tests, road tests and the length of the license renewal cycle generally did not. In terms of policies that apply to all drivers, seatbelt laws, particularly with primary enforcement, were generally the only policies that reduced older driver fatalities. These results are noteworthy because a number of policies that have been effective towards increasing younger driver safety are not relevant for older drivers, implying that policymakers must think broadly about using state laws to improve older driver safety.     

The driver's role in fatal two-car crashes: a paired "case-control" study.

This population-based study examines drivers' characteristics associated with driving errors that resulted in fatal motor vehicle crashes. Routinely collected data from the Fatal Accident Reporting System were used to assess whether a driver initiated the crash (case) or was passively involved (control) in 6,506 two-car collisions (81% of 7,993 eligible events). A paired comparison of cases and controls avoided confounding by environmental factors, exposure to traffic, and differences in case fatality. The strongest predictor of crash initiation is alcohol (odds ratio (OR) = 11.5; 95% confidence interval (CI) 9.57-13.9). Odds ratios are elevated even at the lowest blood alcohol concentration levels and increase dramatically as alcohol levels rise. Drivers aged 40-49 years are least likely to initiate crashes; odds ratios rise in a U-shaped manner to 3.35 in teenagers (95% CI 2.72-4.13) and to 22.1 in drivers over 80 years (95% CI 14.2-34.5). Other risk factors for initiating a fatal crash are the following: not wearing a seat belt (OR = 1.54; 95% CI 1.35-1.75), driving without a valid driver's license (OR = 2.16; 95% CI 1.72-2.73), and having had a crash within the last year (OR = 1.21; 95% CI 1.07-1.38). Driving errors leading to fatal crashes do not occur at random, but are associated with specific driver characteristics. The risk factors for crash initiation among crash-involved drivers are similar to risk factors for crash involvement found in other studies. These findings suggest that driving errors often explain high rates of crash involvement, invite further use of crash initiation in traffic injury research, and underscore the value of population-based registries for analytic epidemiology.     

Automobile driver fatalities in frontal impacts: air bags compared with manual belts.

OBJECTIVES. The effectiveness of air bags was estimated in this study by comparing driver fatalities in frontal crashes with driver fatalities in nonfrontal crashes, for cars with air bags and manual belts and cars with manual belts only. METHODS. Fatal Accident Reporting System data for drivers fatally injured during 1985 to 1991 in 1985 to 1991 model year cars that were equipped with air bags in or before model year 1991 were analyzed. RESULTS. Driver fatalities in frontal crashes in air bag cars were 28% lower than those in comparable cars with manual belts only. This percentage was used for estimating the overall fatality reduction in air bag cars. The reduction was greater in large cars (50%) than in midsize cars (19%) or in small cars (14%). Air bags reduced driver fatalities in frontal crashes involving ejection by about 9%. Fatalities in frontal crashes among drivers who were reportedly using manual belts at the time of the crash were reduced by about 15%. The comparable reduction among drivers who were reportedly not using manual belts was 31%. CONCLUSION. It was estimated that air bags reduced the total number of all driver fatalities by about 19%.     

Causal influence of car mass and size on driver fatality risk

OBJECTIVES: This study estimated how adding mass, in the form of a passenger, to a car crashing head-on into another car affects fatality risks to both drivers. The study distinguished the causal roles of mass and size. METHODS: Head-on crashes between 2 cars, one with a right-front passenger and the other with only a driver, were examined with Fatality Analysis Reporting System data. RESULTS: Adding a passenger to a car led to a 14.5% reduction in driver risk ratio (risk to one driver divided by risk to the other). To divide this effect between the individual drivers, the author developed equations that express each driver's risk as a function of causal contributions from the mass and size of both involved cars. Adding a passenger reduced a driver's frontal crash fatality risk by 7.5% but increased the risk to the other driver by 8.1%. CONCLUSIONS: The presence of a passenger reduces a driver's frontal crash fatality risk but increases the risk to the driver of the other car. The findings are applicable to some single-car crashes, in which the driver risk decrease is not offset by any increase in harm to others. When all cars carry the same additional cargo, total population risk is reduced.     

Drivers aged 16 or 17 years involved in fatal crashes --- United States, 2004-2008

Motor vehicle crashes are the leading cause of death among teens in the United States, accounting for approximately one third of deaths in this age group. Crash risk is highest during the first years of independent driving. To characterize trends in fatal crashes involving drivers aged 16 or 17 years, CDC analyzed data from the Fatality Analysis Report System (FARS) for 2004-2008. This report summarizes the results of that analysis, which indicated that, during 2004-2008, a total of 9,644 passenger vehicle drivers aged 16 or 17 years were involved in fatal crashes. During that period, the annual population-based rate for drivers aged 16 or 17 years involved in fatal crashes declined 38%, from 27.1 per 100,000 population in 2004 to 16.7 in 2008. By state, 5-year annualized rates for drivers aged 16 or 17 years involved in fatal crashes ranged from 9.7 per 100,000 population in New Jersey and New York to 59.6 in Wyoming. To further reduce fatal crashes involving young drivers, states should periodically reexamine and update graduated driver licensing (GDL) programs, and communities should vigorously enforce laws on minimum legal drinking age, blood alcohol concentration (BAC), and safety belt use, all of which can reduce the number of fatal crashes among young drivers.     

High Ambient Temperatures and Risk of Motor Vehicle Crashes in Catalonia,Spain (2000–2011): A Time-Series Analysis

Background

Experimental studies have shown a decrease in driving performance at high temperatures. The epidemiological evidence for the relationship between heat and motor vehicle crashes is not consistent.

Objectives

We estimated the impact of high ambient temperatures on the daily number of motor vehicle crashes and, in particular, on crashes involving driver performance factors (namely distractions, driver error, fatigue, or sleepiness).

Methods

We performed a time-series analysis linking daily counts of motor vehicle crashes and daily temperature or occurrence of heat waves while controlling for temporal trends. All motor vehicle crashes with victims that occurred during the warm period of the years 2000–2011 in Catalonia (Spain) were included. Temperature data were obtained from 66 weather stations covering the region. Poisson regression models adjusted for precipitation, day of the week, month, year, and holiday periods were fitted to quantify the associations.

Results

The study included 118,489 motor vehicle crashes (an average of 64.1 per day). The estimated risk of crashes significantly increased by 2.9% [95% confidence interval (CI): 0.7%, 5.1%] during heat wave days, and this association was stronger (7.7%, 95% CI: 1.2%, 14.6%) when restricted to crashes with driver performance–associated factors. The estimated risk of crashes with driver performance factors significantly increased by 1.1% (95% CI: 0.1%, 2.1%) for each 1°C increase in maximum temperature.

Conclusions

Motor vehicle crashes involving driver performance–associated factors were increased in association with heat waves and increasing temperature. These findings are relevant for designing preventive plans in a context of global warming.

Citation

Basagaña X, Escalera-Antezana JP, Dadvand P, Llatje Ò, Barrera-Gómez J, Cunillera J, Medina-Ramón M, Pérez K. 2015. High ambient temperatures and risk of motor vehicle crashes in Catalonia, Spain (2000–2011): a time-series analysis. Environ Health Perspect 123:1309–1316; http://dx.doi.org/10.1289/ehp.1409223     

Vulnerability of female drivers involved in motor vehicle crashes: an analysis of US population at risk

Objectives. Motor vehicle trauma has been effectively reduced over the past decades; however, it is unclear whether the benefits are equally realized by the vehicle users of either sex. With increases in the number of female drivers involved in fatal crashes and similarity in driving patterns and risk behavior, we sought to evaluate if advances in occupant safety technology provide equal injury protection for drivers of either sex involved in a serious or fatal crash.Methods. We performed a retrospective cohort study with national crash data between 1998 and 2008 to determine the role of driver sex as a predictor of injury outcome when involved in a crash.Results. The odds for a belt-restrained female driver to sustain severe injuries were 47% (95% confidence interval = 28%, 70%) higher than those for a belt-restrained male driver involved in a comparable crash.Conclusions. To address the sex-specific disparity demonstrated in this study, health policies and vehicle regulations must focus on effective safety designs specifically tailored toward the female population for equity in injury reduction.Motor vehicle–related trauma is the leading cause of unintentional injuries resulting in the highest number of fatalities among those aged 5 to 34 years in the United States.¹ The overall consequence of motor vehicle trauma on the health of the US population, as measured by the disability-adjusted life-years metric, indicates that approximately 449 healthy life-years per 100 000 population were lost as a result of premature mortality and disability attributable to the health condition.² To address this public health concern, the Healthy People 2020 project initiated by US Department of Health and Human Services targets reducing motor vehicle–related mortality and injury rates by 10% in the current decade (compared with figures estimated in 2007).³ Specifically among the injuries, the project focuses on reducing fatal and nonfatal traumatic brain injuries and spinal cord injuries. To realize these objectives, the framework of the Healthy People 2020 project prioritizes certain vision-based goals, one of which specifically aims at eliminating health disparities among demographic segments including differences that occur by gender or sex. To identify steps targeted toward reducing motor vehicle–related injuries within this framework, it is of interest to evaluate whether sex-specific disparity plays a role in the effectiveness of prevalent motor vehicle safety systems.Traffic data over the past decades have consistently demonstrated that female drivers are underrepresented in fatal or serious injury motor vehicle crashes; female drivers exhibit approximately one third the rate of fatal crash involvement per driver compared with male drivers (Figure 1).⁴ Subsequently, the burden on health caused by motor vehicle trauma is 2-fold higher for males (age-adjusted disability-adjusted life-years for male and female road traffic victims were 600 and 296 life-years per 100 000 population, respectively).² The trends in the fatality rates between the 2 sexes is better understood by analyzing the related individual factors: crash fatality rate (proportion of fatal crashes among all crashes), crash incidence density (number of crashes per annual vehicle miles traveled), and driving exposure (annual vehicle miles traveled per licensed driver).Open in a separate windowFIGURE 1Fatal crash involvement rate and crash involvement rate in the US population by sex.Data indicate that although the driving exposure among male drivers has been consistently higher (33% more annual vehicle miles traveled per driver in 2009),⁵ the crash incidence density is in fact higher for female drivers (1.52 vs 1.26 injurious crashes per million vehicle miles traveled for female and male drivers, respectively, in 2009).^4,5 As studies confirm, the trend for the decreasing difference in the crash involvement rate (per licensed driver) for the 2 sexes is indicative of increasing exposure—both licensing and travel miles—and socioeconomic changes in driving behavior among female drivers.^6–8 Therefore, despite a higher fatality involvement rate for male drivers, traffic trends indicate that future female drivers may be equally as likely to be involved in a crash.Becauses male and female drivers are expected to have comparable exposure to traffic crashes, it is necessary that motor vehicle safety systems provide equitable injury protection to occupants of either sex involved in moderate to serious crashes. Owing to the relatively high exposure and fatal crash involvement rate, standard adult occupant safety systems (seatbelt, airbags, and other passive safety devices) have been designed and evaluated with a focus on the occupant characteristics typically representing the male population. It should be noted that the effectiveness and the performance of such safety devices is, however, sensitive to biological and biomechanical considerations including occupant age, anthropometric size, injury tolerance, and the mechanical response of the affected body region. Because sex is expected to be highly correlated with these variables (except age), it is hypothesized that current advances in safety technology optimized for male characteristics may not be equally effective in protecting female occupants.Our objective was to evaluate whether a female driver restrained by the safety belt sustains a similar risk of moderate to serious injuries compared with a belt-restrained male driver when involved in a comparable crash. The results would highlight the importance of future advances in occupant safety technology to specifically focus on reducing the sex-specific disparity, if any, as an important step toward the mitigation of overall traffic injury–related health burden.     

Using head-on collisions to compare risk of driver death by frontal air bag generation: a matched-pair cohort study

US air bag regulations were changed in 1997 to allow tests of unbelted male dummies in vehicles mounted and accelerated on sleds, resulting in longer crash pulses than rigid-barrier crashes. This change facilitated depowering of frontal air bags and was intended to reduce air bag-induced deaths. Controversy ensued as to whether sled-certified air bags could increase adult fatality risk. A matched-pair cohort study of two-vehicle, head-on, fatal collisions between drivers involving first-generation versus sled-certified air bags during 1998-2005 was conducted by using Fatality Analysis Reporting System data. Sled certification was ascertained from public information and a survey of automakers. Conditional Poisson regression for matched-pair cohorts was used to estimate risk ratios adjusted for age, seat belt status, vehicle type, passenger car size, and model year for driver deaths in vehicles with sled-certified air bags versus first-generation air bags. For all passenger-vehicle pairs, the adjusted risk ratio was 0.87 (95% confidence interval: 0.77, 0.98). In head-on collisions involving only passenger cars, the adjusted risk ratio was 1.04 (95% confidence interval: 0.85, 1.29). Increased fatality risk for drivers with sled-certified air bags was not observed. A borderline significant interaction between vehicle type and air bag generation suggested that sled-certified air bags may have reduced the risk of dying in head-on collisions among drivers of pickup trucks.     

Impact of an educational program on the safety of high-risk, visually impaired, older drivers

BACKGROUND: Older drivers (licensed drivers aged 60 years and older) have among the highest rates of motor vehicle collision involvement per mile driven of all age groups. Educational programs that promote safe driving strategies among seniors are a popular approach for addressing this problem, but their safety benefit has yet to be demonstrated. The objective of this study was to determine whether an individualized educational program that promoted strategies to enhance driver safety reduces the crash rate of high-risk older drivers. DESIGN/ SETTING: Randomized, controlled, single-masked intervention evaluation at an ophthalmology clinic. PARTICIPANTS: A total of 403 older drivers with visual acuity deficit or slowed visual processing speed or both who were crash-involved in the previous year, drove at least 5 days or 100 miles per week or both, and were at least 60 years old. INTERVENTION: Patients were randomly assigned to usual care (comprehensive eye examination) or usual care plus an individually tailored and administered educational intervention promoting safe-driving strategies. MAIN OUTCOME MEASURE: Police-reported vehicle collision rate, expressed both in terms of person-years of follow-up and person-miles of travel for 2 years postintervention. RESULTS: The intervention group did not differ significantly from the usual care only group in crash rate per 100 person-years of driving (relative risk [RR], 1.08; 95% confidence interval [CI], 0.71-1.64) and per 1 million person-miles of travel (RR, 1.40; 95% CI, 0.92-2.12). The intervention group reported more avoidance of challenging driving maneuvers and self-regulatory behaviors during follow-up than did the usual care only group (p<0.0001). CONCLUSIONS: An educational intervention that promoted safe-driving strategies among visually impaired, high-risk older drivers did not enhance driver safety, although it was associated with increased self-regulation and avoidance of challenging driving situations and decreased driving exposure by self-report.     

Efficacy of side air bags in reducing driver deaths in driver-side collisions

Side air bags, a relatively new technology designed to protect the head and/or torso in side-impact collisions, are becoming increasingly common in automobiles. Their efficacy in preventing US driver deaths among cars struck on the near (driver's) side was examined using data from the Fatality Analysis Reporting System and the General Estimates System. Risk ratios for driver death per nearside collision during 1999-2001 were computed for head/torso and torso-only side air bags in cars from model years 1997-2002, relative to cars without side air bags. Confounding was addressed by adjusting nearside risk ratios for front- and rear-impact mortality, which is unaffected by side air bags. Risk ratios were 0.55 (95% confidence interval: 0.43, 0.71) for head/torso air bags and 0.89 (95% confidence interval: 0.79, 1.01) for torso-only air bags. Risk was reduced when cars with head/torso air bags were struck by cars/minivans (significant) or pickup trucks/sport utility vehicles (nonsignificant). Risk was reduced in two-vehicle collisions and among male drivers and drivers aged 16-64 years. Protective effects associated with torso-only air bags were observed in single-vehicle crashes and among male and 16- to 64-year-old drivers. Head/torso side air bags appear to be very effective in reducing nearside driver deaths, whereas torso-only air bags appear less protective.     

Sleep, sleepiness and motor vehicle accidents: a national survey

OBJECTIVE: To assess the role of sleep-related factors, ethnicity and socioeconomic deprivation in self-reported motor vehicle accidents while driving, after controlling for gender, age and driving exposure. METHODS: Mail survey to a random electoral roll sample of 10,000 people aged 30-60 years, stratified by age decades and ethnicity (71% response rate). The analytical sample included 5,534 current drivers (21.6% Maori men, 21.2% Maori women, 30% non-Maori men, 27.2% non-Maori women). RESULTS: Multiple logistic regression analyses revealed the following independent risk factors for accident involvement while driving (last three years): being younger; higher average weekly driving hours; never/rarely getting enough sleep (OR=1.26, 95% CI 1.06-1.49); reporting any chance of dozing in a car while stopped in traffic (Epworth Sleepiness Scale question 8, OR=1.52, 95% CI 1.15-2.02); and among women, being non-Maori. Total Epworth score was not significantly related to reported accident involvement. CONCLUSIONS: Chronic sleep restriction, and any likelihood of dozing off at the wheel of a motor vehicle, were significant independent predictors of self-reported involvement in all types of motor vehicle accidents, not only those identified as fatigue-related. The Epworth Sleepiness Scale alone is not a reliable clinical tool for identifying individuals at higher risk of crashes. IMPLICATIONS: Factors relating to chronic sleepiness were as important as established demographic risk factors for self-reported motor vehicle accident involvement among 30-60 year-old drivers. The findings reinforce the need for multi-faceted campaigns to reduce sleepy driving.     

Is body mass index a risk factor for motor vehicle driver injury? A cohort study with prospective and retrospective outcomes

OBJECTIVE: To investigate the association between risk of motor vehicle driver injury and body mass index (BMI). METHODS: In a cohort study of 10 525 New Zealand men and women, BMI was assessed in 1992-1993 (baseline), and data on deaths and hospitalizations for motor vehicle driver injury were obtained by record linkage to national health databases for the period 1988-1998. Hazard ratios (HR) and CI were estimated by Cox regression. RESULTS: During a mean 10.3 years of follow-up, 139 fatal and non-fatal driver injury cases occurred (85 before baseline and 54 after). A U-shaped association was observed between driver injury risk and BMI, both crudely and after adjustment for covariates, which included age, sex, driving exposure, and alcohol intake (P-values for quadratic trend /=28.7 kg/m(2); HR = 2.00, 95% CI: 1.18-3.39) and lowest (<23.5 kg/m(2); HR = 2.17, 95% CI: 1.27-3.73) quartiles of BMI were twice as likely to have experienced a driver injury during the follow-up period as participants in the reference quartile (25.9-28.6 kg/m(2); HR = 1.00). CONCLUSION: Further research is needed to corroborate or refute the hypothesis that BMI is a risk factor for serious motor vehicle driver injury.     

Risks older drivers face themselves and threats they pose to other road users

BACKGROUND: Although there is an ever increasing literature on older drivers, there is no comprehensive up-to-date presentation of how older drivers are impacted by traffic safety, and how they impact the road safety of others. METHODS: This paper uses 1994-1996 US data to determine how many rates related to traffic safety depend on the age and sex of road users (fatalities, fatalities per licensed driver, etc.) Threats drivers pose to other road users are estimated by driver involvement in pedestrian fatality crashes. RESULTS: It is found that renewing the licence of a 70-year-old male driver for another year poses, on average, 40% less threat to other road users than renewing the license of a 40-year-old male driver. The fatality risks drivers themselves face generally increase as they age, with the increased risk of death in the same severity crash being a major contributor. If this factor is removed, crash risks for 70-year-old male drivers are not materially higher than for 40-year-old male drivers; for female drivers they are. CONCLUSIONS: Most driver rates increase substantially by age 80, in many cases to values higher than those for 20-year-olds. Given that a death occurs, the probability that it is a traffic fatality declines steeply with age, from well over 20% for late teens through mid twenties, to under one per cent at age 65, and under half a per cent at age 80.     

Age-specific patterns of factors related to fatal motor vehicle traffic crashes: focus on young and elderly drivers

This population-based study examines patterns of fatal motor vehicle traffic crashes (MVTCs) by age group (16–24, 25–64, 65+) among Canadian drivers.The Canadian Traffic Accident Information Databank (TRAID) provided information about fatal MVTCs between 1984 and 1993. Distribution of risk factors was compared by age group. Crude odds ratios and 95% CIs were calculated for both young and elderly drivers compared with middle-aged drivers. The middle-age group was selected as reference population since it demonstrates the lowest risk of fatality.Compared to the middle-aged group, young drivers demonstrated excess risk for (1) risk-taking behaviours and conditions, specifically alcohol and illicit drug use, speeding, non use of seat belts, fatigue and falling asleep, and inexperience; (2) crashes during the summer, during weekends and at night; and (3) single-vehicle collisions and on performing overtaking manoeuvres. Excess risk among elderly drivers was noted for (1) medical and physical conditions, inattention and inexperience; (2) driver actions, for example, improper turning, failure to yield right-of-way; (3) occurrence on weekdays and during the day; and (4) collisions at intersection and vehicle–vehicle sideswipes.The results show notable differences in risk factors by age group and confirm the need for preventive efforts that incorporate age-specific strategies.     

Slippery road conditions and fatal motor vehicle crashes in the northeastern United States, 1998-2002

OBJECTIVES: We investigated risk factors for fatal motor vehicle crashes on slippery roads in the Northeastern United States, 1998-2002. METHODS: We analyzed data from the Fatality Analysis Reporting System of the National Highway Traffic Safety Administration. RESULTS: Rates of crashes on slippery roads, and ratios of crashes on slippery roads to crashes on dry roads, were greatest among the youngest drivers. Among those aged 16 to 19 years, logistic regression analysis showed significant, independent risks associated with excessive speed for conditions (odds ratio [OR]=1.38), time of day (OR=1.80 for 5:00 to 9:00 am vs 10:00 am to 2:00 pm), time of year (OR=6.17 for January vs July), type of road (OR=1.27 for rural vs urban roads ), and age (OR=1.19 for those aged 16 to 17 years vs those aged 18 to 19 years). Licensure from states with graduated licensing programs was protective against crashes attributed to swerving on slippery roads (adjusted OR = 0.63). Risk factors among drivers older than 19 years were similar but peaked at different times of day and included increased risks for women compared with men. CONCLUSIONS: Driver training programs need to better address hazards presented by slippery roads.     

Mortality reduction with air bag and seat belt use in head-on passenger car collisions

To assess the efficacy of occupant protection systems, the authors measured the mortality reduction associated with air bag deployment and seat belt use for drivers involved in head-on passenger car collisions in the United States. They used a matched case-control design of all head-on collisions involving two passenger cars reported to the Fatality Analysis Reporting System in 1992-1997, and driver mortality differences between the paired crash vehicles for air bag deployment and seat belt use were measured with matched-pair odds ratios. Conditional logistic regression was used to adjust for multiple effects. There were 9,859 head-on collisions involving 19,718 passenger cars and drivers. Air bag deployment reduced mortality 63% (crude odds ratio (OR) = 0.37, 95% confidence interval (CI): 0.32, 0.42), while lap-shoulder belt use reduced mortality 72% (OR = 0.28, 95% CI: 0.25, 0.31). In a conditional logistic model that adjusted for vehicle (rollover, weight, age) and driver (age, sex) factors, air bags (OR = 0.71, 95% CI: 0.58, 0.87) and any combination of seat belts (OR = 0.25, 95% CI: 0.22, 0.29) were both associated with reduced mortality. Combined air bag and seat belt use reduced mortality by more than 80% (OR = 0.18, 95% CI: 0.13, 0.25). Thus, this study confirms the independent effect of air bags and seat belts in reducing mortality.     

The effects of mandatory seatbelt laws on seatbelt use, motor vehicle fatalities, and crash-related injuries among youths

We provide the first comprehensive assessment of the effects of mandatory seatbelt laws on self-reported seatbelt use, highway fatalities, and crash-related injuries among high school age youths using data from the Centers for Disease Control's (CDC) national, state, and local Youth Risk Behavior Surveys (YRBS) and the Fatality Analysis Reporting System (FARS) from 1991 to 2005, a period spanning over 20 changes in state seatbelt laws. Our quasi-experimental approaches isolate the independent effects of seatbelt laws net of demographic characteristics, area and year fixed effects, and smooth area-specific trends. Across all data sources, we find consistent evidence that state mandatory seatbelt laws - particularly those permitting primary enforcement - significantly increased seatbelt use among high school age youths by 45-80%, primarily at the extensive margin. Unlike previous research for adults, however, we find evidence against the selective recruitment hypothesis: seatbelt laws had consistently larger effects on those most likely to be involved in traffic accidents (drinkers, alcohol-involved drivers). We also find that mandatory seatbelt laws significantly reduced traffic fatalities and serious injuries resulting from fatal crashes by 8 and 9%, respectively. Our results suggest that if all states had primary enforcement seatbelt laws then regular youth seatbelt use would be nearly universal and youth fatalities would fall by about 120 per year.     

Driver and passenger seatbelt use among U.S. high school students

BACKGROUND: In 2005, 40% of motor-vehicle occupant deaths in the group aged 16-19 years involved passengers. Although seatbelts can reduce crash mortality by 50% or more, little is known about the differences in driver-versus-passenger seatbelt use among teens. METHODS: In 2007, data from the 2001 and 2003 Youth Risk Behavior Surveys were analyzed for 12,731 black, white, and Hispanic high school students aged >/=16 years reporting seatbelt use as both drivers and passengers. Seatbelt use was compared for driver- and passenger-seat positions, and stratified by age, gender, race/ethnicity, school grades, and histories of either drinking and driving or riding with a drinking driver. RESULTS: Overall, 59% of students always used seatbelts when driving, but only 42% always buckled up as passengers. Across all covariate strata, passenger seatbelt use was significantly less prevalent than driver seatbelt use (p<0.001). A concordance analysis showed that only 38% of students always wore seatbelts both when driving and while riding as a passenger. Multivariate analyses indicated that, regardless of seat position, seatbelt use was lower for young men, blacks, students with poor grades, and students who reported either drinking and driving or riding with a drinking driver. CONCLUSIONS: U.S. high school students aged >/=16 years are significantly less likely to wear seatbelts as passengers than as drivers. Interventions designed to promote seatbelt use among teens need to address this disparity.     

Effect of environmental factors on the risk of death for drivers of two-wheeled motorized vehicles involved in road crashes

OBJECTIVES: To assess the effect of environmental factors on the risk of death for drivers of two-wheeled motorized vehicles (TWMV) after a crash. METHODS: We studied a case series comprising all 309,626 drivers of TWMV involved in road crashes with victims compiled by the Spanish Department of Transportation from 1993 to 2002. The dependent variable was death of the driver. Environmental factors included temporal variables (year, month, day and hour of the crash) and spatial variables (area where the accident took place and light conditions, among others). Confounding variables related to the driver (age, sex, helmet use), the vehicle, and the type of crash were also recorded. Poisson regression models were constructed to obtain crude and adjusted relative risks for each environmental condition. RESULTS: In the adjusted analysis, no association was found between most time-related factors and the risk of death, with the exception of an increased risk in the early hours of the morning. The risk of death was much greater for crashes on open roads (especially highways and motorways) than in urban areas, where the risk of death increased as the size of the town decreased. CONCLUSIONS: After adjustment for several confounders, the only environmental factors related to the risk of death in TWMV drivers after a crash were the area when the crash occurred, and (more weakly) the time of day when it occurred.