Mandatory seat belt laws in the states. A study of fatal and severe occupant injuries

Patients with Abrasion or Ecchymosis Seat Belt Sign Have High Risk for Abdominal Injury, but Initial Computed Tomography is 100% Sensitive

BACKGROUND

Trauma providers seek to accurately assess the risk of patients with abdominal seat belt sign (ASBS). As hospital costs continue to rise, identification of strategies to safely discharge emergency department (ED) patients has become crucial.

OBJECTIVES

The purpose of this study is to 1) describe a large cohort of patients by type of ASBS and 2) determine the value of computed tomography (CT) of the abdomen and pelvis as a screening tool to rule out intra-abdominal injury (IAI) and support discharge of stable patients.

METHODS

We conducted a retrospective case series of all patients presenting to our urban, Level I trauma center from 2013-2015. We studied motor vehicle collision patients who presented with ASBS. We further classified individuals into ASBS groups: Abrasion, Ecchymosis, Abrasion + Ecchymosis, or Unknown ASBS to examine differences between groups.

RESULTS

In one of the largest described cohorts, the ASBS remained associated with IAI, most commonly, solid organ injury. Of 425 patients, 36.1% had some IAI on CT, but only 13.6% required laparotomy. Categorizing the type of skin injury in ASBS, we found that both abrasion and ecchymosis were associated with IAI. Initial CT performed with 100% sensitivity.

CONCLUSIONS

This study shows that ED trauma patients with significant seat belt abrasion or contusion can have IAI. With the very high sensitivity of modern abdominal CT scanners, clinicians could consider safe ED discharge of stable ASBS patients while providing strong return precautions. Our large cohort strengthens the evidence on decision-making in ASBS patients to ensure outcomes and use of health care resources.

The persistent southern disadvantage in US early life mortality, 1965-2014

BACKGROUND

Recent studies of US adult mortality demonstrate a growing disadvantage among southern states. Few studies have examined long-term trends and geographic patterns in US early life (ages 1 to 24) mortality, ages at which key risk factors and causes of death are quite different than among adults.

OBJECTIVE

This article examines trends and variations in early life mortality rates across US states and census divisions. We assess whether those variations have changed over a 50-year time period and which causes of death contribute to contemporary geographic disparities.

METHODS

We calculate all-cause and cause-specific death rates using death certificate data from the Multiple Cause of Death files, combining public-use files from 1965-2004 and restricted data with state geographic identifiers from 2005-2014. State population (denominator) data come from US decennial censuses or intercensal estimates.

RESULTS

Results demonstrate a persistent mortality disadvantage for young people (ages 1 to 24) living in southern states over the last 50 years, particularly those located in the East South Central and West South Central divisions. Motor vehicle accidents and homicide by firearm account for most of the contemporary southern disadvantage in US early life mortality.

CONTRIBUTION

Our results illustrate that US children and youth living in the southern United States have long suffered from higher levels of mortality than children and youth living in other parts of the country. Our findings also suggest the contemporary southern disadvantage in US early life mortality could potentially be reduced with state-level policies designed to prevent deaths involving motor vehicles and firearms.

Primary Enforcement of Mandatory Seat Belt Laws and Motor Vehicle Crash Deaths

INTRODUCTION

Policies that allow directly citing motorists for seat belt non-use (primary enforcement) have been shown to reduce motor vehicle crash deaths relative to secondary enforcement, but the evidence base is dated and does not account for recent improvements in vehicle designs and road safety. The purpose of this study was to test whether recent upgrades to primary enforcement still reduce motor vehicle crash deaths.

METHODS

In 2016, researchers used motor vehicle crash death data from the Fatal Analysis Reporting System for 2000-2014 and calculated rates using both person- and exposure-based denominators. Researchers used a difference-in-differences design to estimate the effect of primary enforcement on death rates, and estimated negative binomial regression models, controlling for age, substance use involvement, fixed state characteristics, secular trends, state median household income, and other state-level traffic safety policies.

RESULTS

Models adjusted only for crash characteristics and state-level covariates models showed a protective effect of primary enforcement (rate ratio, 0.88, 95% CI=0.77, 0.98; rate difference, -1.47 deaths per 100,000 population, 95% CI= -2.75, -0.19). After adjustment for fixed state characteristics and secular trends, there was no evidence of an effect of upgrading from secondary to primary enforcement in the whole population (rate ratio, 0.98, 95% CI=0.92, 1.04; rate difference, -0.22, 95% CI= -0.90, 0.46) or for any age group.

CONCLUSIONS

Upgrading to primary enforcement no longer appears protective for motor vehicle crash death rates.

Road crash injuries and fatalities in Isfahan, Iran from March 2006 to March 2009

With rapid development of social economies, road traffic accidents have continued to increase, and have become the primary public hazard to humans. The main goal of the present study was to investigate road traffic crash (RTC) fatalities and injuries in the city of Isfahan, Iran. A sample of 150,940 accident cases was considered from Isfahan Police Safety Driving Department, involving drivers and passengers of all ages, and covering a 3-year period. The record linkage identified 24,608 drivers and passengers injured or died as a result of RTC in the city of Isfahan over the 3-year period. The finding of this study shows that the highest rate of RTC fatality was 40% and 58%, which comprises the male drivers and female passengers within the age classes 25-34 and 35-44, respectively. On average, there were one death every 3 days and every hour, someone was injured and taken to an emergency department for RTCs in the city of Isfahan. The highest men to women death and injured ratios were 4:1 and 2:1, respectively. The use of seat belt devices in our population was worrisome. The article ends with a number of recommended measures for the improvement of road safety.

Importance of muscle activations for biofidelic pediatric neck response in computational models

OBJECTIVE

During dynamic injury scenarios, such as motor vehicle crashes, neck biomechanics contribute to head excursion and acceleration, influencing head injuries. One important tool in understanding head and neck dynamics is computational modeling. However, realistic and stable muscle activations for major muscles are required to realize meaningful kinematic responses. The objective was to determine cervical muscle activation states for 6-year-old, 10-year-old, and adult 50th percentile male computational head and neck models. Currently, pediatric models including muscle activations are unable to maintain the head in an equilibrium position, forcing models to begin from nonphysiologic conditions. Recent work has realized a stationary initial geometry and cervical muscle activations by first optimizing responses against gravity. Accordingly, our goal was to apply these methods to Duke University's head-neck model validated using living muscle response and pediatric cadaveric data.

METHODS

Activation schemes maintaining an upright, stable head for 22 muscle pairs were found using LS-OPT. Two optimization problems were investigated: a relaxed state, which minimized muscle fatigue, and a tensed activation state, which maximized total muscle force. The model's biofidelity was evaluated by the kinematic response to gravitational and frontal impact loading conditions. Model sensitivity and uncertainty analyses were performed to assess important parameters for pediatric muscle response. Sensitivity analysis was conducted using multiple activation time histories. These included constant activations and an optimal muscle activation time history, which varied the activation level of flexor and extensor groups, and activation initiation and termination times.

RESULTS

Relaxed muscle activations decreased with increasing age, maintaining upright posture primarily through extensor activation. Tensed musculature maintained upright posture through coactivation of flexors and extensors, producing up to 32 times the force of the relaxed state. Without muscle activation, the models fell into flexion due to gravitational loading. Relaxed musculature produced 28.6-35.8 N of force to the head, whereas tensed musculature produced 450-1023 N. Pediatric model stiffnesses were most sensitive to muscle physiological cross-sectional area.

CONCLUSIONS

Though muscular loads were not large enough to cause vertebral compressive failure, they would provide a prestressed state that could protect the vertebrae during tensile loading but might exacerbate risk during compressive loading. For example, in the 10-year-old, a load of 602 N was produced, though estimated compressive failure tolerance is only 2.8 kN. Including muscles and time-variant activation schemes is vital for producing biofidelic models because both vary by age. The pediatric activations developed represent physiologically appropriate sets of initial conditions and are based on validated adult cadaveric data.

Epidemiology of motor vehicle crashes in Utah

OBJECTIVES

This study describes the frequency and pattern of vehicle crashes and safety belt use in Utah; the proportion of vehicle crashes involving safety belt use, alcohol, and fatigue; and the influence these factors and others have on emergency room visits or hospital admissions and on the severity of the outcome.

METHODS

Data were obtained from the Utah Department of Transportation, Division of Traffic and Safety, from 1999 through 2005. Motor vehicle crash (MVC) data were linked to statewide hospital admission (inpatient) and emergency department (ED) records.

RESULTS

The trend in rates of crashes significantly decreased for both males and females, with rates of crashes involving alcohol decreasing for males but increasing for females and rates of crashes involving fatigue remaining constant for males and females over the study period. Drivers not wearing a safety belt or intoxicated or fatigued were significantly more likely to have contributed to the crash, visit the emergency room, be admitted to the hospital, and experience severe injury or death. Drivers in crashes who were intoxicated or fatigued were significantly less likely to be wearing a safety belt. When a safety belt was worn at the time of the crash, sitting in the front seat was safer than in the second or third seats, and sitting on the left side of the vehicle was safer than on the right side or in the middle. However, when a safety belt was not worn at the time of the crash, sitting in the front seat was more likely associated with injury or death than in the second or third seats or sitting in the middle seat.

CONCLUSION

Drivers in crashes who were intoxicated or fatigued were less likely to be wearing a safety belt and more likely to have contributed to the crash and experience serious injury or death. Severity of injury related to seat placement is moderated by safety belt use.

Road traffic injuries in Iran: the role of interventions implemented by traffic police

INTRODUCTION

In Iran there are about 70 deaths per day from road traffic injuries (RTIs). Despite some interventions having been implemented during the past 5 years, the impacts of these interventions on mortality and morbidity rates have not been well evaluated.

OBJECTIVE

To ascertain and describe the epidemiological pattern of RTIs in Iran for the years 2004 to 2007 and to compare the epidemiological trends of RTIs, before and 2 years after four road safety programs were put into place.

METHODS

A 4-year database from two sources, the traffic police and medico-legal data, was employed. The morbidity and death rates per 10,000 vehicles and per 100,000 populations were calculated as were the odds ratios (ORs) for before and after these national interventional programs. The four interventions concurrently/simultaneously put into place in 2005 were (1) enforcement of laws on the mandatory fastening of seat belts, (2) enforcement of the laws on use of motorcycle helmets, (3) enforcement of general traffic laws, and (4) mass media educational campaigns on national radio and television.

FINDINGS

There was a significant decrease in RTI-related death and morbidity rates in Iran, after the intervention programs were conducted (P < 0.001). The death rate decreased from 38.2 per 100,000 in 2004 to 31.8 in 2007 (OR = 0.83, 95% CI = 0.82-0.85). The death rate per 10,000 vehicles also showed a significant decline from 24.2 to 13.4 (OR = 0.56, 95% CI = 0.55-0.57). Similar reductions were seen among nonfatal RTIs.

CONCLUSION

These findings demonstrate the role of traffic police interventions, initiated simultaneously on a national level, in RTI prevention. Though these reductions may not be solely attributable to the interventions implemented, they do highlight the importance of the contribution made by law enforcement and mass education campaigns.

The effect of state regulations on truck-crash fatalities

To improve traffic safety, states limit truck length and weight, and some set lower speed limits for trucks than for other vehicles. We examined the impact of truck-specific restrictions and general traffic-safety policies on fatality rates from crashes involving large trucks. We used state-level data from 1991 to 2005 with a cross-sectional time-series model that controlled for several policy measures. We found that higher speed limits for cars and trucks contributed to higher fatality rates, but differential speed limits by vehicle type had no significant impact. Truck-length limitations reduced fatalities in crashes involving large trucks. Our model estimates suggested that if all states had adopted a speed limit of 55 miles per hour for all vehicles in 2005, an additional 561 fatalities would have been averted.

A comprehensive statewide analysis of seatbelt non-use with injury and hospital admissions: new data, old problem

OBJECTIVES

To investigate the association of seatbelt nonuse with injury patterns, injury severity, and in-patient hospital admission among adults presenting to emergency departments (EDs) in a statewide, population-based, sample of motor vehicle crashes.

METHODS

Using data from the 2002 Crash Outcome Data Evaluation System (CODES) for Wisconsin, 23,920 occupants of motor vehicle crashes, aged 16 years or older, who were treated in an ED, were analyzed. Logistic regression was used to compare the odds ratio of having sustained an injury to specific body regions and of being admitted to an inpatient unit in unbelted individuals compared with those who were belted.

RESULTS

Compared with belted occupants presenting to an ED, their unbelted counterparts were more likely to be male (56% vs. 40%) and to have used alcohol (17% vs. 4%). Unbelted occupants were younger (31 years vs. 38 years) and incurred higher ED charges ($681 vs. $509) than belted occupants. Additionally, unbelted occupants have a higher proportion of single-vehicle crashes, such as rollovers (44% vs. 22%), and rural crashes (56% vs. 44%). Unbelted occupants comprised 20% of study patients treated in the ED and discharged, 44% of patients treated in the ED and admitted, and 68% of patients dying in the ED. Unbelted occupants were more likely to be admitted (odds ratio [OR] = 2.6) than belted individuals and were more likely to suffer severe injuries to the head, face, thorax, abdomen, spine, upper and lower extremities (OR ranging from 1.6 to 3.9).

CONCLUSIONS

Among patients presenting to an ED after a motor vehicle crash, unbelted occupants are more likely to require inpatient admission and to have sustained a severe injury to numerous body regions than are belted occupants.

Effectiveness of primary enforcement safety belt laws and enhanced enforcement of safety belt laws: a summary of the Guide to Community Preventive Services systematic reviews

BACKGROUND

The use of safety belts is the single most effective means of reducing fatal and nonfatal injuries in motor-vehicle crashes. This paper summarizes the systematic reviews of two interventions to increase safety belt use: primary enforcement safety belt laws and enhanced enforcement of safety belt laws. The reviews were previously published in the American Journal of Preventive Medicine.

METHODS

We conducted the systematic reviews using the methodology developed for the Guide to Community Preventive Services.

RESULTS

These reviews provide strong evidence that primary laws are more effective than secondary laws in increasing safety belt use and decreasing fatalities and that enhanced enforcement is effective in increasing safety belt use. Increases in belt use are generally highest in states with low baseline rates of belt use.

DISCUSSION

Primary safety belt laws and enhanced enforcement programs tend to result in greater increases in usage rates for target groups with lower baseline rates. Concerns regarding public opposition to these interventions may impede their implementation in some jurisdictions. However, surveys indicate that a substantial majority of the public supports implementation of both primary laws and enhanced enforcement programs.

CONCLUSION

Based on the strong evidence for effectiveness of primary safety belt laws and enhanced enforcement programs, the Task Force on Community Preventive Services recommended that all states enact primary safety belt laws and that communities implement enhanced enforcement programs.

Seatbelt legislation in Japan: high risk driver mortality and seatbelt use

OBJECTIVES

To clarify why seatbelt legislation did not achieve the expected reduction in mortality in Japan. LOCATION AND BACKGROUND: Seatbelt legislation was enacted in Japan in September 1985 and penalties were introduced in November 1986.

METHODS

The driver deaths per vehicle km traveled (D/VKT) were calculated to adjust for changes in traffic volume. Decreases in D/VKT were compared with the reduction expected after legislation. The association between percentage changes of driver D/VKT, seatbelt use rate, and seatbelt non-use rate were explored. Deaths of passengers, pedestrians, and cyclists were also examined. Mortality data were obtained from vital statistics, traffic volume figures from the Ministry of Land, Infrastructure, and Transport, and seatbelt use rates from the National Police Agency.

RESULTS

Although the decrease in D/VKT after the law was enforced was larger than the absolute number of deaths, it was far less than predicted. The percentage decrease in seatbelt non-use rate showed the strongest correlation with the percentage decrease in driver mortality. Mortality did not increase among other road users after the law was enacted.

CONCLUSION

Accurate evaluation of the effect of seatbelt legislation must take into account changes in traffic volume. The selective recruitment hypothesis-that high risk drivers were less responsive to seatbelt legislation-fits well with the findings. There was no conclusive evidence supporting risk compensation-that is, an increase in injuries among other road users.

Traffic safety and the switch to a primary seat belt law: the California experience

This study explores whether the change of an existing seat belt law from secondary to primary enforcement enhances traffic safety. In particular, we examine traffic fatalities and injuries in California from 1988 to 1997. During the first half of this period, California law provided for secondary enforcement of its mandatory seat belt law, but in 1993 it upgraded the law to primary enforcement. Controlling for the number of motor vehicle collisions, a Box-Tiao intervention analysis of the time series is used to compare the monthly fatalities and injuries before and after the change in the enforcement provision. The results show that California experienced an improvement in traffic safety in terms of a significant reduction in injuries, but the change in enforcement provision had no statistically significant impact on fatalities.

Reviews of evidence regarding interventions to reduce alcohol-impaired driving

BACKGROUND

Alcohol-related motor vehicle crashes are a major public health problem, resulting in 15,786 deaths and more than 300,000 injuries in 1999. This report presents the results of systematic reviews of the effectiveness and economic efficiency of selected population-based interventions to reduce alcohol-impaired driving.

METHODS

The Guide to Community Preventive Services's methods for systematic reviews were used to evaluate the effectiveness of five interventions to decrease alcohol-impaired driving, using changes in alcohol-related crashes as the primary outcome measure.

RESULTS

Strong evidence was found for the effectiveness of .08 blood alcohol concentration laws, minimum legal drinking age laws, and sobriety checkpoints. Sufficient evidence was found for the effectiveness of lower blood alcohol concentration laws for young and inexperienced drivers and of intervention training programs for servers of alcoholic beverages. Additional information is provided about the applicability, other effects, and barriers to implementation of these interventions.

CONCLUSION

These reviews form the basis of the recommendations by the Task Force on Community Preventive Services presented elsewhere in this supplement. They can help decision makers identify and implement effective interventions that fit within an overall strategy to prevent impaired driving.

Reviews of evidence regarding interventions to increase the use of safety belts

BACKGROUND

The use of safety belts is the single most effective means of reducing fatal and nonfatal injuries in motor vehicle crashes. If all motor vehicle occupants consistently wore safety belts, an estimated 9553 deaths would have been prevented in 1999 alone.

METHODS

The Guide to Community Preventive Services's methods for systematic reviews were used to evaluate the effectiveness of three interventions to increase safety belt use. Effectiveness was assessed on the basis of changes in safety belt use and number of crash-related injuries.

RESULTS

Strong evidence was found for the effectiveness of safety belt laws in general and for the incremental effectiveness of primary safety belt laws relative to secondary laws. Strong evidence for the effectiveness of enhanced enforcement programs for safety belt laws was also found. Additional information is provided about the applicability, other effects, and barriers to implementation of these interventions.

CONCLUSIONS

These reviews form the basis of the recommendations by the Task Force on Community Preventive Services presented elsewhere in this supplement. They can help decision makers identify and implement effective interventions that fit within an overall strategy to increase safety belt use.

Implications of the 65-mph speed limit for traffic safety

This study evaluates the impact of the 65-mph speed limit on traffic safety. Using data for the years 1981 to 1995 for all 50 states, a pooled time series analysis is conducted. Separate models are estimated for state fatality rates on four categories of roads: rural interstate highways, rural noninterstate roads, all roads except for rural interstate highways, and all roads. It is reported that the 65-mph speed limit increased fatality rates on rural interstate highways but was correlated with a reduction in state fatality rates on the three other categories of roads.