Obesity and risk for death due to motor vehicle crashes

The Effects of Recline Angle and Restraint Geometry on Lap Belt-Pelvis Interaction for Above-Normal BMI Motor Vehicle Occupants

The interaction of the three-point seat belt with the occupant, particularly the lap belt with the pelvis, is affected by a multitude of intrinsic and extrinsic factors, including the torso recline angle, lap belt angle, and occupant body mass index (BMI). While field data analyses have shown the strong safety benefit for seat belt use regardless of occupant size or crash direction, the term "submarining" historically has been used to describe a scenario in which the lap belt loads the abdominal soft tissue and organs, superior and posterior to the pelvic bone. While contemporary restraint systems work to effectively address the risk of submarining in occupants properly seated and properly belted, scenarios in which the lap belt may not properly engage the load-bearing pelvis remain. These scenarios, including a reclined torso angle or shallow lap belt angle, require further study. In this research study, eight non-injurious seated belt pull tests were conducted on two constrained whole-body cadavers of above-normal BMI (≥ 25 kg/m2) with controlled variation of torso and lap belt-pelvis angles. Test factors affecting belt engagement with the pelvis were identified for each subject. Belt engagement was largely affected by the initial placement of the lap belt. The initial belt placement was affected by the torso angle which influenced the distribution of the abdominal soft tissue. The belt disengagement thresholds differed between subjects due to the inter-subject differences in soft tissue distribution, which affected the lap belt kinematics relative to the pelvis. In addition to improving the understanding of this particular submarining mechanism, this study provides a dataset for future validation of human body model soft tissue deformation response from lap belt loading.

Obese Occupant Response in Reclined and Upright Seated Postures in Frontal Impacts

The American population is getting heavier and automated vehicles will accommodate unconventional postures. While studies replicating mid-size and upright fore-aft seated occupants are numerous, experiments with post-mortem human subjects (PMHS) with obese and reclined occupants are sparse. The objective of this study was to compare the kinematics of the head-neck, torso and pelvis, and document injuries and injury patterns in frontal impacts. Six PMHS with a mean body mass index of 38.2 ± 5.3 kg/m2 were equally divided between upright and reclined groups (seatback: 23°, 45°), restrained by a three-point integrated belt, positioned on a semi-rigid seat, and exposed to low and moderate velocities (15, 32 km/h). Data included belt loads, spinal accelerations, kinematics, and injuries from x-rays, computed tomography, and necropsy. At 15 km/h speed, no significant difference in the occupant kinematics and evidence of orthopedic failure was observed. At 32 km/h speed, the primary difference between the cohorts was significantly larger Z displacements in the reclined occupant at the head (190 ± 32 mm, vs. 105 ± 33 mm p < 0.05) and femur (52 ± 18 mm vs. 30 ± 10 mm, p < 0.05). All the moderate-speed tests produced at least one thorax injury. Rib fractures were scattered around the circumference of the rib-cage in the upright, while they were primarily concentrated on the anterior aspect of the rib-cage in two reclined specimens. Although MAIS was the same in both groups, the reclined specimens had more bi-cortical rib fractures, suggesting the potential for pneumothorax. While not statistical, these results suggest enhanced injuries with reclined obese occupants. These results could serve as a data set for validating the response of restrained obese anthropometric test device (ATDs) and computational human body models.

Protective Role of Obesity on Trauma Impact: A Retrospective Analysis of Patients with Surgical Blunt Bowel Mesenteric Injury Due to Road Traffic Accidents

Background

The "cushion effect" theory proposes that increased body mass index (BMI) is associated with less severe abdomen injury following blunt abdomen trauma, while the "obesity paradox" describes the protective effect of obesity against mortality. However, most previous studies used the abdominal abbreviated injury scale as the outcomes seemed to be inadequate owing to the injuries to the abdominal organs, such as the spleen and liver, which may be attributable to the force that caused the chest trauma. This study aimed to use adult trauma patients with surgical blunt bowel mesenteric injuries (BBMIs) to investigate the influence of obesity on the clinical outcomes and overall morbidities.

Methods

This retrospective study reviewed the data of all hospitalized trauma patients between 2009 and 2019 and included all patients with surgically proven small bowel, colon, or mesenteric injuries due to a road traffic accident. Comparison of the outcomes was performed among 123 patients with surgically proven BBMI, who were categorized by BMI into the normal-weight (n = 73, BMI<25 kg/m²), overweight (n = 37, 25≤BMI≤30 kg/m²), and obese groups (n = 13, BMI>30 kg/m²).

Results

The obese group had a significantly lower incidence of isolated bowel injury (0%) compared with the normal-weight (35.6%) and overweight (16.2%) groups (p=0.005), but with higher incidence of isolated mesenteric injury or combined injury, although this was not significant. The obese group (92.3%) had a significantly higher percentage of overall morbidity than the normal-weight (61.6%) and overweight (70.3%) groups (p = 0.047). No significant difference was observed in the in-hospital mortality and 24-hour mortality among the three study groups.

Conclusion

The study findings do not support the existence of a cushion effect and obesity paradox of obesity in blunt abdominal trauma.

A radiographic and physical analysis of factors affecting seat belt position in sitting car seat

The characteristic subcutaneous hemorrhage along the seat belt in motor vehicle accidents is called the seat belt sign (SBS). The risk of organ injuries is especially high when abdominal SBS is located above the anterior superior iliac spine (ASIS). The purpose of this study analyzed the physical and radiographic factors of healthy volunteers sit on car seat that affect initial position of abdominal seat belt, namely "lap belt", related to the seat belt injury. This study was examined prospectively relation between physical characteristics of one hundred healthy volunteers and lap belt position sitting the car seat. Physical findings were clarified age, sex, height, body mass index (BMI), and waist circumference. Radiographical findings were measured lumber lordosis (LL), sacral slope (SS), and initial lap belt position by marking with lead tape for the center and ASIS of the lap belt installed on the driver's car seat. In the lateral X-ray image, we measured the horizontal distance (X-value) and vertical distance (Z-value) from the ASIS to the central marker. The lap belt angle was determined to measure the angle between the horizontal line and the straight line connecting the upper edges of the markers. Statistical analysis of the relationships between physical characteristics and radiological findings was performed. X-value and Z-value were positively correlated with body weight, BMI, and waist circumference, while the lap belt angle was negatively correlated with body weight, BMI, and waist circumference. The relationship between physical characteristics and the initial position of seat belt was analyzed. Since the lap belt is positioned higher than the ASIS in occupants with a high BMI, it is likely to cause seat belt injury. This analysis can help to develop safer seat belts and to enlighten car occupants.

Relationship between Vehicle Safety Ratings and Drivers' Injury Severity in the Context of Gender Disparity

Previous studies have analyzed the relationship between vehicle safety ratings from impact tests and actual crash injury severity. Nevertheless, no study has investigated the relationship in the context of gender disparity. The main objective of this paper is to explore the validity of the 5-star ratings of the U.S. National Highway Traffic Safety Administration, which describes vehicles’ protectiveness, using actual traffic crash data by gender. Random parameter models are developed using 2015–2020 two-vehicle crash data from Maryland, United States. According to the data, over 90% of vehicles have 4–5 stars in overall, front-impact, and side-impact 5-star ratings. After controlling other factors, it is shown that woman drivers are more likely to be seriously injured in two-vehicle crashes than men drivers when using vehicles with the same 5-star safety ratings. Moreover, there is significant individual heterogeneity in the effect of vehicles with different 5-star safety ratings on driver injury severity. Using vehicles with more stars can reduce the risk of being seriously injured for most man drivers. However, the probability of woman drivers being seriously injured is reduced by approximately 5% on average by using vehicles with higher star ratings in the overall and front-impact 5-star rating, and individual heterogeneity shows a difference of nearly 50% in positive and negative effects. The overall and front-impact 5-star ratings of vehicles could not provide reasonable information as the safety performance of vehicles in traffic crashes for woman drivers. On the other hand, drivers’ residence, driving characteristics, crash types, and environmental characteristics are significantly associated with the injury severity. It is expected that the results from this study will contribute to guide a better vehicle safety design for both men and women.

Lifestyle Matters: Effects of Habitual Physical Activity on Driving Skills in Older Age

Research on multitasking driving has suggested age-related deterioration in driving performance. It has been shown that physical and cognitive functioning, which are related to driving performance and decline with aging, are positively associated with physical activity behavior. This study aimed to explore whether driving performance decline becomes severe with advancing age and whether physical activity behavior modifies age-related deterioration in driving performance. A total of one hundred forty-one healthy adults were categorized into three groups based on their age; old-old (74.21 ± 2.33 years), young-old (66.53 ± 1.50 years), and young adults (23.25 ± 2.82 years). Participants completed a realistic multitasking driving task. Physical activity and cardiorespiratory fitness levels were evaluated. Older groups drove more slowly and laterally than young adults, and old-old adults drove slower than young-old ones across the whole driving course. Physical activity level did not interact with the aging effect on driving performance, whereas cardiovascular fitness interacted. Higher-fitness young-old and young adults drove faster than higher-fitness old-old adults. Higher-fitness old adults drove more laterally than higher-fitness young adults. The present study demonstrated a gradual decline in driving performance in old adults, and cardiorespiratory fitness interacted with the aging effect on driving performance. Future research on the interaction of aging and physical activity behavior on driving performance in different age groups is of great value and may help deepen our knowledge.

Is optimized restraint system for an occupant with obesity different than that for a normal BMI occupant?

OBJECTIVE

To optimize the components of restraint systems for protecting obese (BMI = 35 kg/m²) and normal BMI (BMI = 25) human body models (HBMs) in frontal crash simulations, and to compare the two optimized designs.

METHODS

The Life Years Lost metric, which incorporates the risk of injury and long-term disability to different body regions, was used as the optimization objective function. Parametric simulations, sampled from a 15-parameter design space using the Latin Hypercube technique, were performed and metamodels of the HBM responses were developed. A genetic algorithm was applied to the metamodels to identify the optimized designs.

RESULTS

While most of the restraint parameters between the optimized design for obese and normal BMI HBMs were similar, the main difference was that the restraint for the obese HBM included an under-the-seat airbag, which mitigated its lower extremity excursion, improved its torso kinematics, and decreased its lower extremity and lumbar spine injury risks. The optimized designs for both HBMs included an inflatable seat belt, which reduced the risk of thoracic injury.

CONCLUSIONS

The design recommendations from this study should be considered to improve safety of occupants with obesity.

The Lack of Sex, Age, and Anthropometric Diversity in Neck Biomechanical Data

Female, elderly, and obese individuals are at greater risk than male, young, and non-obese individuals for neck injury in otherwise equivalent automotive collisions. The development of effective safety technologies to protect all occupants requires high quality data from a range of biomechanical test subjects representative of the population at risk. Here we sought to quantify the demographic characteristics of the volunteers and post-mortem human subjects (PMHSs) used to create the available biomechanical data for the human neck during automotive impacts. A systematic literature and database search was conducted to identify kinematic data that could be used to characterize the neck response to inertial loading or direct head/body impacts. We compiled the sex, age, height, weight, and body mass index (BMI) for 999 volunteers and 110 PMHSs exposed to 5,431 impacts extracted from 63 published studies and three databases, and then compared the distributions of these parameters to reference data drawn from the neck-injured, fatally-injured, and general populations. We found that the neck biomechanical data were biased toward males, the volunteer data were younger, and the PMHS data were older than the reference populations. Other smaller biases were also noted, particularly within female distributions, in the height, weight, and BMI distributions relative to the neck-injured populations. It is vital to increase the diversity of volunteer and cadaveric test subjects in future studies in order to fill the gaps in the current neck biomechanical data. This increased diversity will provide critical data to address existing inequities in automotive and other safety technologies.

Does a "Cushion Effect" Really Exist? A Morphomic Analysis of Vulnerable Road Users with Serious Blunt Abdominal Injury

Introduction: The severity of injury from motor vehicle crashes (MVCs) depends on complex biomechanical factors, and the bodily features of the injured person account for some of these factors. By assuming that vulnerable road users (VRUs) have limited protection resulting from vehicles and safety equipment, the current study analyzed the characteristics of fat distribution measured by computed tomography (CT) imaging and investigated the existence of a "cushion effect" in VRUs. Materials and Methods: This retrospective study enrolled 592 VRUs involved in MVCs who underwent CT scans. Visceral fat area and subcutaneous fat cross-sectional area were measured and adjusted according to total body area (TBA) and are presented as the visceral fat ratio and the subQ fat ratio (subcutaneous fat ratio). Risk factors for serious abdominal injury (maximum abbreviated injury scale (MAIS_abd ≥ 3)) resulting from MVCs were determined by univariate and multivariate analysis. Results: MAIS_abd ≥ 3 was observed in 104 (17.6%) of the patients. The subQ fat ratio at the L4 vertebral level was significantly lower in the MAIS_abd ≥ 3 group than in the MAIS_abd < 3 group (24.9 ± 12.0 vs. 28.1 ± 11.9%; p = 0.015). A decreased L4 subQ fat ratio was associated with a higher risk for MAIS_abd ≥ 3 in multivariate analysis (odds ratio 0.063; 95% CI 0.008-0.509; p = 0.009). Conclusion: The current study supported the "cushion effect" theory, and protection was apparently provided by subcutaneous fat tissue. This concept may further improve vehicle and safety designation in the future.

The Association of Body Mass Index and Outcomes in Adult Patients with Chest Wall Injuries

BACKGROUND

Thoracic injury secondary to rib fractures following motor vehicle collisions (MVCs) significantly contribute to morbidity and mortality. While obesity has reached epidemic proportions, little is known regarding how BMI impacts outcomes in MVCs. The aim of this study was to examine how BMI impacts outcomes in MVC patients with rib fractures.

METHODS

The ACS-TQIP Database was utilized to evaluate adult MVC patients with ≥3 rib fractures. Patients with a non-thoracic AIS ≥3 were excluded, to focus on chest injuries. Patients were sorted according to the presence or absence of flail chest injuries and BMI into groups with a low (<15), intermediate (15-24), or severe (≥25) ISS.

RESULTS

Overweight and obese patients in the non-flail cohort had decreased odds of pneumothorax in all ISS groups (P < 0.05). Overweight (P = 0.049) and obese (P = 0.011) patients in the low ISS non-flail cohort had decreased odds of splenic laceration. In the non-flail cohort, obese patients with a low and intermediate ISS had decreased odds of pulmonary contusion (P < 0.01). Obese patients in the low and intermediate ISS non-flail cohorts had increased odds of PE (P < 0.05). In both the flail and non-flail cohorts, obese patients with an intermediate ISS had decreased odds of liver laceration (P < 0.05), as well as a longer HLOS, ICU-LOS, and mechanical ventilation time (P < 0.01).

CONCLUSION

Obesity affects associated injuries, complications, and hospital outcomes in a complex way after MVC related chest wall trauma. Thus, the effect of BMI should be taken into consideration when assessing and treating obese MVC trauma patients.

Assessing the Cushion Effect: A Systematic Review and Meta-Analysis of the Role of Obesity in Motor Vehicle Injuries and Fatalities

PURPOSE

A systematic review and meta-analysis were done to evaluate the effect of obesity in injury and mortality due to motor vehicle accidents.

MATERIALS & METHODS

The systematic review consisted of 20 studies meeting the inclusion criteria. The meta-analysis was conducted on these studies to analyze obesity as a risk factor for specific injuries, as well as overall injury and mortality compared to non-obese patients.

RESULTS

The data revealed that obesity was associated with increased lower extremity injuries (odds ratio [OR] = 1.44, 95% confidence interval [CI] = 1.19-1.69, P ≤ 0.05), neck injuries (OR = 3.38, 95% CI = 1.58-5.19, P ≤ 0.05), and overall mortality (OR = 1.51, 95% CI = 1.40-1.61, P ≤ 0.05). When stratified for obesity class with class I as BMI >30.1-34.9, class II BMI 35-39.9, and class III BMI >40, only class II (OR = 1.20, 95% CI = 1.15-1.24, P ≤ 0.05) and class III (OR = 1.49, 95% CI = 1.30-1.68, P ≤ 0.05) were associated with increased mortality risk. No significant differences were seen with head, upper extremity, thoracic, abdominal, or pelvic injuries.

CONCLUSION

Obesity is a risk factor in motor vehicle accidents for fatality and injury, specifically lower extremity and neck injuries.

A state-of-the-art review of factors that predict mortality among traumatic injury patients following a road traffic crash

BACKGROUND

Traffic related injuries are a major public health problem worldwide with millions of people dying every year. The objective of this state-of-the-art review was to identify the factors reported in the literature as being associated with mortality for trauma patients following road traffic crashes.

METHOD

A systematic search was undertaken of PubMed/MEDLINE, EMBASE, CINAHL, Web of Science, and Cochrane Library databases to identify articles published in the past two decades (2000-2020). Of 8257 records, 4507 remained for title, abstract and full text screening after duplicates were removed. The level of evidence of selected studies was assessed using The National Health and Medical Research Council (NHMRC) guideline.

RESULTS

This review included eighty primary research studies examining mortality risk factors following a road traffic crash. The study identified factors in five categories; (i) demographic factors; (ii) behavioural factors; (iii) crash characteristics; (iv) environmental and timing factors; (v) injury severity and pre-injury/condition. The primary studies are summarised in a matrix. Included studies included level II to level IV levels of evidence based on the NHMRC criteria.

CONCLUSION

This study shows that there are a large number of factors associated with increased risk of mortality following diverse types of traffic crashes. Understanding these wide-ranging factors can strengthen injury and mortality prevention by guiding decision makers about where to focus strategy implementation.

Socioeconomic Status, Health and Lifestyle Settings as Psychosocial Risk Factors for Road Crashes in Young People: Assessing the Colombian Case

The social determinants of health influence both psychosocial risks and protective factors, especially in high-demanding contexts, such as the mobility of drivers and non-drivers. Recent evidence suggests that exploring socioeconomic status (SES), health and lifestyle-related factors might contribute to a better understanding of road traffic crashes (RTCs). Thus, the aim of this study was to construct indices for the assessment of crash rates and mobility patterns among young Colombians who live in the central region of the country. The specific objectives were developing SES, health and lifestyle indices, and assessing the self-reported RTCs and mobility features depending on these indices. A sample of 561 subjects participated in this cross-sectional study. Through a reduction approach of Principal Component Analysis (PCA), three indices were constructed. Mean and frequency differences were contrasted for the self-reported mobility, crash rates, age, and gender. As a result, SES, health and lifestyle indices explained between 56.3–67.9% of the total variance. Drivers and pedestrians who suffered crashes had higher SES. A healthier lifestyle is associated with cycling, but also with suffering more bike crashes; drivers and those reporting traffic crashes have shown greater psychosocial and lifestyle-related risk factors. Regarding gender differences, men are more likely to engage in road activities, as well as to suffer more RTCs. On the other hand, women present lower healthy lifestyle-related indices and a less active implication in mobility. Protective factors such as a high SES and a healthier lifestyle are associated with RTCs suffered by young Colombian road users. Given the differences found in this regard, a gender perspective for understanding RTCs and mobility is highly suggestible, considering that socio-economic gaps seem to differentially affect mobility and crash-related patterns.

Body Mass Index and Mortality in Blunt Trauma: The Right BMI can be Protective

BACKGROUND

There are limited studies examining the role of BMI on mortality in the trauma population. The aim of this study was to analyze whether the "obesity paradox" exists in non-elderly patients with blunt trauma.

METHODS

A retrospective study was performed on the Trauma Quality Improvement Program (TQIP) database for 2016. All non-elderly patients aged 18-64, with blunt traumatic injuries were identified. A generalized additive model (GAM) was built to assess the association of mortality and BMI adjusted for age, gender, race, and injury severity score (ISS).

RESULTS

28,475 patients (mean age = 42.5, SD = 14.3) were identified. 20,328 (71.4%) were male. Age (p < 0.0001), gender (p < 0.0001), and ISS (p < 0.0001) had significant associations with mortality. After GAM, BMI showed a significant U-shaped association with mortality (EDF = 3.2, p = 0.003). A BMI range of 31.5 ± 0.9 kg/m² was associated with the lowest mortality.

CONCLUSION

High BMI can be a protective factor in mortality within non-elderly patients with blunt trauma. However, underweight or morbid obesity suggest a higher risk of mortality.

Exploring the role of delta-V in influencing occupant injury severities - A mediation analysis approach to motor vehicle collisions

This study investigates the impact that delta-V, the relative change in vehicle velocity pre- and post-crash, has on the severity of motor vehicle collisions (MVCs). We study injury severity using two metrics for each occupant - the number of injuries suffered, and the probability of suffering a serious or worse (MAIS 3+) injury. We use a cross-sectional set of generally-representative MVC data between 2010 and 2015 as a basis for our research. Collision factors that influence the crash environment are combined with the injuries that were suffered in MVCs. The influence of delta-V is captured using a mediation analysis, whereby delta-V acts as the focal point between crash factors and injury outcome. The mediation approach adds to existing research by presenting a detailed view of the relationship between injury severity, delta-V and other collision factors. We find evidence of competitive mediation, wherein a collision factor's positive association with injury severity is offset by a negative association with delta-V. Neglecting to include delta-V in our study would have let the factor's association with injury severity go undiscovered. In addition, certain collision factors are found to be related to injury severity solely because of delta-V, while others are found to have a significant impact regardless of delta-V. Our results support the multitude of policy recommendations that promote seatbelt use and warn against alcohol-impaired driving, and support the proliferation of safety-enabled vehicles whose technology can mitigate the bodily damage associated with detrimental crash types.

When Can I Drive? Predictors of Returning to Driving After Total Joint Arthroplasty

INTRODUCTION

A common question by patients considering total joint arthroplasty (TJA) is when can I return to driving. The ability to return to driving has enormous effect on the independence of the patient, ability to return to work, and other activities of daily living. With advances in accelerated rehabilitation protocols, newer studies have questioned the classic teaching of waiting 6 weeks after TJA. The goal of this prospective study was to determine specific patient predictors for return to driving and create individualized models able to estimate return to driving based on patient risk factors for both total knee arthroplasty (TKA) and total hip arthroplasty (THA).

METHODS

From July 2017 to January 2018, 554 primary TKA and 490 primary THA patients were prospectively enrolled to obtain information regarding return to driving. Patients were sent a survey every 2 weeks regarding their return to driving. Additional information regarding vehicle type, transmission, and involvement in motor vehicle accidents was collected. Bivariate analysis was done followed by the creation of a multiple linear regression models to analyze return to driving after TKA and THA.

RESULTS

The majority (98.2%, 1,025/1,044) of patients returned to driving within 12 weeks of surgery. On average, patients returned to driving at 4.4 and 3.7 weeks for TKA and THA (P < 0.001), respectively. The rate of motor vehicle accidents was 0.7% (7/1,044) within 12 weeks after surgery with no injuries reported. After multivariate analysis, baseline return to driving began at 10.9 days for TKA and 17.1 days for THA. The following predictors added additional time to return to driving for TJA: not feeling safe to drive, limited range of motion, female sex, limitations due to pain, other limitations, discharge to a rehabilitation facility, right-sided procedures, limited ability to break, preoperative anemia, and preoperative use of a cane.

DISCUSSION

Important predictors identified for return to driving were sex, joint laterality, limited ability to walk or ability to break, and feeling safe. Surgeons should consider these factors when counseling patients on their postoperative expectations regarding driving after TJA.

Relationships between Body Mass Index and Self-Reported Motorcycle Crashes in Vietnam

The relationship between overweight, obesity, or body mass index (BMI) and crashes among drivers of passenger cars, vans, and trucks has been the focus of much research. However, little is understood about this relationship among motorcyclists, particularly motorcycle taxi drivers who tend to work long hours. Motorcycle taxis are an increasingly popular and important mode of travel in many cities, especially in South-East Asia, due partly to the rise of ride-hailing services. This paper assesses the body mass index (BMI) of motorcycle taxi drivers in Vietnam and its impacts on crashes among three types of drivers (traditional, ride-hailing, and hybrid). Data from a structured questionnaire survey of motorcycle taxi drivers conducted in Hanoi, Vietnam were used. Results show that 18.8% of motorcycle taxi drivers were overweight or obese whereas only 1.4% were underweight. Fulltime motorcycle taxi drivers were more likely to be overweight or obese. Results of random effect binary logistic regression show that overweight and obese motorcycle taxi drivers had significantly higher overall and injury crash risks, when compared to normal-weight motorcycle taxi drivers. Results also indicate that hybrid motorcycle taxi drivers had lower overall and injury crash risks when compared to traditional motorcycle taxi drivers.

The relationship between weight indices and injuries and mortalities caused by the motor vehicle accidents: a systematic review and meta-analysis

BACKGROUND

The relationship between weight indices and injuries and mortality in motor vehicle accidents is unknown. Systematic review studies addressing the collection and analysis of the relationship in investigations are very limited. The purpose of this systematic review is to determine the relationship between BMI, obesity and overweight with mortality and injuries and their severity and vulnerable organs after the motor vehicle accident.

METHODS

The databases (MEDLINE/PUBMED, EMBASE, Web of Science, etc) were searched for relevant abstracts using certain keywords. Of all the articles, similar ones were removed considering different filters. The collected data were entered into the STATA SE v 13.1. The heterogeneity of the data was analyzed using i2 statistics. In addition, the estimates of the study were done based on the age group (children and adults) and the impact of obesity on different regions of the body.

RESULTS

A direct relationship was observed between the overall BMI and the degrees of injuries (CI=0.503-1.139), and mortality due to motor vehicle accident (CI=1.267-1.471). A positive relationship was found between obesity and AIS+2 (CI=0.653-1.426), and AIS+3 (CI=1.184-1.741), and ISS (CI=1.086-1.589). Also, a negative relationship between overweight and injuries rates, and a direct relationship between overweight and mortality (CI=0.979-1.167), and injuries with index of AIS+2 (CI=1.178-0.768) and AIS+3 (CI=0.48-2.186) were found.

CONCLUSIONS

The prediction of injury, mortality and severity of injuries in the motor vehicle accident by the variable of obesity and overweight determines the need to design prevention programs for this vulnerable group at all levels.

Nonlinear models of injury risk and implications in intervention targeting for thoracic injury mitigation

OBJECTIVE

Field data analyses often use either parametric or nonparametric means to describe the relationship between risk and various predictor variables. This study sought to evaluate a hybrid approach using semiconstrained multivariate nonlinear spline-based analysis.

METHODS

Data were compiled from NASS-CDS years 1998-2015, selecting belted occupants age 16+ in collisions with a principal direction of force (PDOF) from 10 o'clock to 2 o'clock. Outcome measures included the incidence of Maximum Abbreviated Injury Scale (MAIS) 3+ injury in general and Abbreviated Injury Scale (AIS) 3+ rib fracture injury. Multivariate logistic regression models were fit controlling for PDOF, ΔV, vehicle model year, collision year, occupant age, occupant body mass index (BMI), and other select factors. Within the logistic regression models, each of the continuous variables was modeled with a 4-knot spline. These were compared to models treating ΔV and BMI linearly.

RESULTS

A total of 29,667 occupants were observed from the query, representing approximately 13,608,398 occupants when weighted. Sixty percent of the AIS 3+ rib fracture cases occurred at ΔVs at or below 40 km/h. The median age for cases without AIS 3+ rib fracture was 34 years old. The median age for cases with AIS 3+ rib fracture was 62 years old. When modeled via nonlinear spline, the risk of MAIS 3+ injury in general and AIS 3+ rib fracture injury specifically exhibited a relationship with ΔV similar in shape to that observed in the linear model. In both cases, the spline model exhibited greater risk prediction over ΔVs from 25 to 50 km/h compared to the linear model (20-33% greater risk at ΔVs below 40 km/h) and less risk than the linear model at greater ΔVs. BMI exhibited a nonlinear, nonmonotonic relationship with both injury types studied. The risk tended to be a minimum at BMIs of 22-24 kg/m², with an increase in risk at both higher and lower BMIs. For AIS 3+ rib fracture, the risk for a person with a BMI of 18 was approximately equal to the risk for a person with a BMI of 30, both being approximately 40% greater than the risk associated with a BMI of 24.

CONCLUSIONS

Nonlinear multivariate regression methods have the potential to convey information about the risk-predictor relationship that cannot be captured through traditional linear modeling. These results suggest that traditional linear logistic regression models may underestimate the risk of AIS 3+ rib fracture injury in the ΔV range where they most frequently occur (below 50 km/h). Due to its nonmonotonic effect, traditional linear models may underestimate injury risk at both high and low BMIs.

Age modifies the association between driver's body mass index and death following motor vehicle crashes

OBJECTIVE

We explored the association between body mass index (BMI) and the odds of a driver being fatally injured in a motor vehicle crash (MVC) after controlling for driver, crash, and vehicle factors known to independently contribute to injury severity. We hypothesized that BMI would be related to risk of fatal injury after controlling for other risk factors but that BMI would also interact with age.

METHOD

We analyzed crashes involving 2 passenger type vehicles (1998-2015) from the Fatality Analysis Reporting System using binary logistic regression (with generalized estimating equations) to compute odds ratios and 95% confidence intervals of fatality by BMI status.

RESULTS

Our results indicate that BMI status confers varying levels of risk at different ages. For example, a very low BMI of 18 increased the odds of fatality (relative to BMI = 21.75) more at age 85 (adjusted odds ratio [aOR] = 1.17, 95% confidence interval [CI], 1.09, 1.26) than at age 25 (aOR = 1.03, 95% CI, 1.01, 1.06). Similarly, a very high BMI of 42.5 increased the odds of fatality (relative to BMI = 21.75) more at age 85 (aOR = 2.17, 95% CI, 1.64, 2.87) than at age 25 (aOR = 1.33, 95% CI, 1.21, 1.45). Conversely, a moderate BMI of 27.5 was protective for drivers aged 85 (aOR = 0.94, 95% CI, 0.88, 0.99) but had no effect for drivers aged 25 (aOR = 1.00, 95% CI, 0.98, 1.02). We also found that a higher BMI was associated with higher odds of wearing a seat belt improperly or not wearing one at all.

CONCLUSION

The relationship between BMI and fatality risk needs to be considered by policymakers, public health officials, and vehicle manufacturers to ensure that vehicles are safe for all occupants regardless of their weight, size, or shape.

Patient Safety: Driving After Foot and Ankle Surgery

This article provides a review of the existing literature regarding driving limitations following lower extremity orthopedic surgery. Medicolegal requirements and insurance recommendations are often vague and subject to interpretation. Several studies have examined the impact of surgery and immobilization on brake reaction time. This study summarizes the findings of these studies. Additionally, the authors consider the impact of lower extremity amputations and peripheral vascular disease on driving. Literature regarding opioid use, obesity, sleep apnea, increasing age, and distraction is also reviewed. An improved understanding of these topics will enhance the orthopedic surgeon's ability to counsel patients and optimize their safety.

Thoracolumbar Spine Fracture occurring in Obese People involved in Motor Vehicle Crashes

Crash data from the International Center of Automotive Medicine (ICAM) database, with analytic morphomics, were used to evaluate thoracolumbar spine fractures for obese occupants in frontal crashes. Two BMI (Body Mass Index) groups (non-obese and obese) with a maximum abbreviated injury scale (MAIS) in the spine region of ≥2 (MAIS_6S 2+) were categorised and compared. The fracture types were assessed based on AIS for each occupant. Univariate analyses were conducted to investigate the association between analytic morphomics measures and thoracolumbar spine fracture. The results indicate that MAIS 2+ injury occurred mainly in severe crashes with high delta-V and large intrusion. Transverse process fractures were the most common AIS 2+ fractures, followed by minor compression type fractures (≤ 20% anterior height). Compared to the non-obese occupants, the majority of obese occupants sustained transverse process fractures at lumbar vertebra with a higher incidence ratio. A statistical analysis was conducted, using vehicle, demographic, and morphomic variables, to explain the difference between transverse process fractures and vertebra body compression fractures. Transverse process fractures were related to BMI and vehicle factors (intrusion) in the obese group. In addition, morphomics related to fat distribution, muscle area, and cortical bone density are the major difference between non-obese and obese occupants.

Does obesity affect the position of seat belt loading in occupants involved in real-world motor vehicle collisions?

OBJECTIVE

Previous work has shown that the lap belt moves superior and forward compared to the bony pelvis as body mass index (BMI) increases. The goal of this project was to determine whether the location of lap belt loading is related to BMI for occupants who sustained real-world motor vehicle collisions (MVCs).

METHODS

A national MVC database was queried for vehicle occupants over a 10-year period (2003-2012) who were at least 16 years old, restrained by a 3-point seat belt, sitting in the front row, and involved in a front-end collision with a change in velocity of at least 56 km/h. Cases were excluded if there was not an available computed tomography (CT) scan of the abdomen. CT scans were then analyzed using adipose enhancement of 3-dimensional reconstructions. Scans were assessed for the presence a radiographic seat belt sign (rSBS), or subcutaneous fat stranding due to seat belt loading. In scans in which the rSBS was present, anterior and superior displacement of rSBS from the anterior-superior iliac spine (ASIS) was measured bilaterally. This displacement was correlated with BMI and injury severity.

RESULTS

The inclusion and exclusion criteria yielded 151 cases for analysis. An rSBS could definitively be identified in 55 cases. Cases in which occupants were older and had higher BMI were more likely to display an rSBS. There was a correlation between increasing BMI and anterior rSBS displacement (P <.01 and P <.01, right and left, respectively). There was no significant correlation between BMI and superior displacement of the rSBS (P =.46 and P =.33, right and left, respectively). When the data were examined in terms of relating increasing superior displacement of the lap belt with Injury Severity Scale (P =.34) and maximum Abbreviated Injury Score (AIS) injury severity (P =.63), there was also no significant correlation.

CONCLUSION

The results from this study demonstrated that anterior displacement of the radiographic seat belt sign but not superior displacement increased with higher BMI. These results suggest that obesity may worsen horizontal position but not the vertical position of the lap belt loading during real-world frontal MVCs.

Evaluating an intervention to improve belt fit for adult occupants

INTRODUCTION

Previous laboratory studies have demonstrated that some drivers position their seat belts suboptimally. Specifically, the lap portion of the belt may be higher and farther forward relative to the pelvis than best practice, and the shoulder portion of the belt may be outboard or inboard of mid-shoulder. This study evaluated the performance of a video-based intervention for improving the belt fit obtained by drivers.

METHOD

Twenty-nine adult drivers participated in this study. Belt fit was measured before and after the intervention in participants' vehicles and in a laboratory mockup.

RESULTS

Data from both the in-vehicle and laboratory belt measures found that 95% of participants sampled improved some aspect of lap belt fit. For the in-vehicle test conditions, participants who lowered the lap belt location (Z) after the intervention showed an improvement of 26 mm on average. Among those participants who shifted the horizontal lap belt location rearward (closer to the pelvis), an average improvement of 36 mm was observed. No significant differences were observed between baseline and post-intervention shoulder belt fit.

CONCLUSIONS

The results provide preliminary evidence that an intervention improves driver belt fit. More research is needed to establish what aspects of this intervention affected behavior and how effective such an intervention is in the context of public health.

PRACTICAL APPLICATIONS

These findings can help better inform intervention initiatives to improve occupant belt fit.

Risk factors for crash involvement in older motorcycle riders

A prospective cohort study was conducted to identify risk and protective factors for crash involvement in older motorcyclists. Over a 1-year study period from August 2013 to July 2014, study participants were recruited from local community centers of five cities in Taiwan. People aged ≥60 years who rode a motorcycle at least once per week were eligible and were invited to participate in the study. Among 256 older riders who completed the baseline assessment and at least one of the four follow-up assessments, 79 (33.7%) experienced a motorcycle crash over the study period. Results of the proportional hazards model showed that after controlling for age, gender, and riding distance, older riders who had sustained hearing impairment (hazard ratio (HR)=2.58; 95% confidence interval (CI), 1.30-5.15), rode a motorcycle at speeds of ≥41km/h (HR=2.31; 95% CI, 1.26-4.23), and had experienced a motorcycle crash in the past year (HR=1.81; 95% CI, 1.06-3.09) were more likely to be involved in a crash, compared to their counterparts. Conversely, older riders who were obese (HR=0.43; 95% CI, 0.22-0.82) were less likely to be involved in a crash than those with a normal weight, while longer functional reach distances (HR=0.96; 95% CI, 0.93-0.99) and higher Tinetti balance scores (HR=0.79; 95% CI, 0.69-0.91) were associated with a reduced risk of crash involvement. Among older people riding a motorcycle as their primary source of transportation, several factors associated with the occurrence of motorcycle crashes were identified. Restrictions and modifications of these risk factors may help design effective safety interventions for reducing crash and injury risks of this increasing riding population.

Impact Response Comparison Between Parametric Human Models and Postmortem Human Subjects with a Wide Range of Obesity Levels

OBJECTIVE

Field data analyses have shown that obesity significantly increases the occupant injury risks in motor vehicle crashes, but the injury assessment tools for people with obesity are largely lacking. The objectives of this study were to use a mesh morphing method to rapidly generate parametric finite element models with a wide range of obesity levels and to evaluate their biofidelity against impact tests using postmortem human subjects (PMHS).

METHODS

Frontal crash tests using three PMHS seated in a vehicle rear seat compartment with body mass index (BMI) from 24 to 40 kg/m² were selected. To develop the human models matching the PMHS geometry, statistical models of external body shape, rib cage, pelvis, and femur were applied to predict the target geometry using age, sex, stature, and BMI. A mesh morphing method based on radial basis functions was used to rapidly morph a baseline human model into the target geometry. The model-predicted body excursions and injury measures were compared to the PMHS tests.

RESULTS

Comparisons of occupant kinematics and injury measures between the tests and simulations showed reasonable correlations across the wide range of BMI levels.

CONCLUSIONS

The parametric human models have the capability to account for the obesity effects on the occupant impact responses and injury risks.

When Can I Drive After Orthopaedic Surgery? A Systematic Review

BACKGROUND

Patients often ask their doctors when they can safely return to driving after orthopaedic injuries and procedures, but the data regarding this topic are diverse and sometimes conflicting. Some studies provide observer-reported outcome measures, such as brake response time or simulators, to estimate when patients can safely resume driving after surgery, and patient survey data describing when patients report a return to driving, but they do not all agree. We performed a systematic review and quality appraisal for available data regarding when patients are safe to resume driving after common orthopaedic surgeries and injuries affecting the ability to drive.

QUESTIONS/PURPOSES

Based on the available evidence, we sought to determine when patients can safely return to driving after (1) lower extremity orthopaedic surgery and injuries; (2) upper extremity orthopaedic surgery and injuries; and (3) spine surgery.

METHODS

A search was performed using PubMed and EMBASE^®, with a list of 20 common orthopaedic procedures and the words "driving" and "brake". Selection criteria included any article that evaluated driver safety or time to driving after major orthopaedic surgery or immobilization using observer-reported outcome measures or survey data. A total of 446 articles were identified from the initial search, 48 of which met inclusion criteria; abstract-only publications and non-English-language articles were not included. The evidence base includes data for driving safety on foot, ankle, spine, and leg injuries, knee and shoulder arthroscopy, hip and knee arthroplasty, carpal tunnel surgery, and extremity immobilization. Thirty-four of the articles used observer-reported outcome measures such as total brake time, brake response time, driving simulator, and standardized driving track results, whereas the remaining 14 used survey data.

RESULTS

Observer-reported outcome measures of total brake time, brake response time, and brake force postoperatively suggested patients reached presurgical norms 4 weeks after right-sided procedures such as TKA, THA, and ACL reconstruction and approximately 1 week after left-sided TKA and THA. The collected survey data suggest patients resumed driving 1 month after right-sided and left-sided TKAs. Patients who had THA reported returning to driving between 6 days and 3 months postoperatively. Observer-reported outcome measures showed that patients' driving abilities often are impaired when wearing an immobilizing cast above or below the elbow or a shoulder sling on their dominant arm. Patients reported a return to driving on average 2 months after rotator cuff repair procedures and approximately 1-3 months postoperatively for total shoulder arthroplasties. Most patients with spine surgery had normal brake response times at the time of hospital discharge. Patients reported driving 6 weeks after total disc arthroplasty and anterior cervical discectomy and fusion procedures.

CONCLUSIONS

The available evidence provides a best-case scenario for when patients can return to driving. It is important for observer-reported outcome measures to have normalized before a patient can consider driving, but other factors such as strength, ROM, and use of opioid analgesics need to be considered. This review can provide a guideline for when physicians can begin to consider evaluating these other factors and discussing a return to driving with patients. Survey data suggest that patients are returning to driving before observer-reported outcome measures have normalized, indicating that physicians should tell patients to wait longer before driving. Further research is needed to correlate observer-reported outcome measures with adverse events, such as motor vehicle accidents, and clinical tests that can be performed in the office.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Driver's obesity and road crash risks in the United States

OBJECTIVE

We assessed obesity trends in U.S. drivers involved in fatal crashes since 1999 and distinguished whether crash risk factors were different between obese and nonobese drivers.

METHODS

We included only drivers of passenger cars involved in fatal traffic crashes between January 1, 1999, and December 31, 2012. Obesity was classified according to the World Health Organization guidelines and profiled between 1999 and 2012 using the adjusted prevalence ratio (aPR) from log-binomial regression models. Differences in crash risks (e.g., driver's fatality, drunk driving, seat belt nonuse) between obese and nonobese drivers were estimated as adjusted odds ratios (aORs) using logistic regression models.

RESULTS

A total of 753,024 U.S. drivers were involved in fatal crashes, for which obesity information was available for 534,887. About 56% (n = 299,078) were driving passenger cars. The prevalence of class I obesity increased from 10% in 1999 to 14% in 2012 (aPR = 1.50, 95% confidence interval [CI], 1.42-1.58), class II obesity from 3 to 5% (aPR = 2.22, 95% CI, 2.05-3.01), and class III obesity from 1 to 2% (aPR = 2.65; 95% CI, 2.27-3.10). Compared to nonobese controls, obese drivers had significantly higher risks for fatality (1.10 ≤ aOR ≤ 1.47), seat belt nonuse (1.00 ≤ aOR ≤ 1.21), need for extrication (1.01 ≤ aOR ≤ 1.23), and ambulance transport time ≥30 min (1.01 ≤ aOR ≤ 1.28). Compared to nonobese controls, obese drivers were less likely to drink drive (0.41 ≤ aOR ≤ 0.72) or speed >65 mph (0.78 ≤ aOR ≤ 0.93).

CONCLUSION

The rising national prevalence of obesity extends to U.S. drivers involved in fatal crashes and indicates the need to improve seat belt use, vehicle design, and postcrash care for this vulnerable population.

Traffic Crash Risks in Morbidly Obese Drivers Before and After Weight Loss Surgery

Morbidly obese drivers have a higher risk of road crashes because of associated conditions such as obstructive sleep apnea. We assessed whether weight loss surgery has an impact on subsequent road crash risks in morbidly obese drivers. Our longitudinal self-matched cohort analyses suggest that road crash risks are three times higher in morbidly obese drivers than the population norm. Yet, weight loss surgery yields no significant reductions in crash risks. We found similar results in patients not previously diagnosed with sleep disorders, suggesting the need to clarify the relationship of obesity with road crash risk.

Obese motorcycle riders have a different injury pattern and longer hospital length of stay than the normal-weight patients

Background

The adverse effects of obesity on the physical health have been extensively studied in the general population, but not in motorcycle riders (includes both drivers and pillions). The aim of this study was to compare injury patterns, injury severities, mortality rates, and in-hospital or intensive care unit (ICU) length of stay (LOS) between obese and normal-weight patients who were hospitalized for the treatment of trauma following motorcycle accidents in a level I trauma center.

Methods

Detailed data of 466 obese adult patients with a body mass index (BMI) ≥30 kg/m² and 2701 normal-weight patients (25 > BMI ≥18.5 kg/m²) who had sustained motorcycle accident-related injuries were retrieved from the Trauma Registry System between January 1, 2009 and December 31, 2013. We used the Pearson’s chi-squared test, Fisher’s exact test, and independent Student’s t-test to analyze differences between the two groups.

Results

Compared to normal-weight motorcycle riders, more obese riders were men and drivers as opposed to pillions. In addition, fewer obese motorcycle riders showed alcohol intoxication. Analyses of the patients’ Abbreviated Injury Scale (AIS) scores revealed that obese motorcycle riders presented with a higher rate of injury to the thorax, but a lower rate of injury to the face than normal-weight patients. In addition, obese motorcycle riders had a 2.7-fold greater incidence of humeral, 1.9-fold greater incidence of pelvic, and 1.5-fold greater incidence of rib fractures. In contrast, normal-weight motorcycle riders sustained a significantly higher rate of maxillary and clavicle fractures. Obese motorcycle riders had a significant longer in-hospital LOS than normal-weight motorcycle riders did (10.6 days vs. 9.5 days, respectively; p = 0.044), with an increase in in-hospital LOS of 0.82 days associated with every 10-unit increase in BMI. No statistically significant differences in Injury Severity Score (ISS), New Injury Severity Score (NISS), Trauma-Injury Severity Score (TRISS), mortality, percentage of patients admitted to the ICU, or LOS in the ICU were found between obese and normal-weight patients.

Discussion

No differences of injury severity, mortality, and LOS in the ICU between obese and normal-weight motorcycle riders in this study may be partly attributed to the motorcycle injuries occur at relatively low velocity, considering that the riding of majority of motorcycles are forbidden on highways in Taiwan and that most traffic accidents occur in relatively crowded streets.

Conclusion

Obese motorcycle riders had different injury characteristics and bodily injury patterns than normal-weight motorcycle riders. Moreover, they had a longer in-hospital LOS; this was particularly true for those with pelvic fractures. However, injury severity and mortality were not significantly different between the two groups.

Body Morphology and Its Associations With Thoracolumbar Trauma Sustained in Motor Vehicle Collisions

OBJECTIVE

This study investigates the relationship between body mass index (BMI) and the patterns of thoracolumbar spinal fractures sustained by patients in motor vehicle collisions (MVCs).

DESIGN

The Crash Injury Research and Engineering Network (CIREN) database was used to analyze prospective data on patients involved in MVCs of moderate severity.

METHODS

Thoracolumbar fractures in 631 subjects were analyzed for patient-, vehicle-, and crash-related factors. Spine injuries were classified according to a modified Denis classification system. Subjects were stratified into BMI subgroups that were then analyzed by injury level, fracture pattern, associated systemic injury, and mortality.

RESULTS

Obesity (BMI ≥ 30.0) was found to be associated with a more cephalad level of injury. Mean BMI was higher in 67 patients with fatal outcomes compared with 557 survivors. Patients who sustained a thoracolumbar fracture and another system injury were more likely to be overweight and obese. Among the various fracture patterns analyzed, BMI was highest in patients with extension injuries.

CONCLUSION

This study characterizes the relationship between body morphology and the thoracolumbar injury patterns associated with MVC to improve understanding of the overall morbidity and mortality of these injuries. These results corroborate research demonstrating the unique relationships between patients who are obese and specific patterns of injury and higher injury severity caused by MVCs and establish a rationale for specifically including thoracolumbar spine parameters in crash safety standards.

U-shaped association of body mass index in early adulthood with unintentional mortality from injuries: a cohort study of Swedish men with 35 years of follow-up

OBJECTIVES

To investigate the dose-response association between body mass index (BMI) in young adulthood and the risk of mortality caused by unintentional injuries.

METHODS

We performed a cohort study including 7 43 398 men identified by linkage of the Multigeneration Register and the Military Service Conscription Register. Cox regression models were used to examine crude and adjusted hazard ratios (HRs) and 95% confidence intervals (95% CIs) of the relationships between BMI at age 18-20 years and the risk of death from all unintentional injuries as well as from specific unintentional injuries. We then estimated the population attributable fractions (PAFs)-the proportion of unintentional deaths that was attributable to underweight, overweight and obesity in this population-based cohort.

RESULTS

During 35.9 years of follow-up, 6461 deaths occurred from unintentional injuries, including 3064 deaths from road injury, 978 from poisoning, 503 from falls, 243 from fire and 348 from drowning. Underweight subjects had a higher risk of mortality in all unintentional injuries (HR, 1.05; 95% CI, 1.03-1.10) and mortality in burns (HR, 1.65; 95% CI, 1.13-2.40) compared with BMI between 18.5 and 22.5 kg m(-2) (reference group). BMI >25 kg m(-2) was associated with increased risk of death from all unintentional injuries (HR, 1.36; 95% CI, 1.12-1.65) and road accidents (HR, 1.50; 95% CI, 1.14-1.97). Estimates of PAF suggested that 4.4% of the mortality in Swedish men caused by unintentional injuries could have been avoided if BMI values were kept between 18.5 and 22.5 kg m(-2).

CONCLUSIONS

A U-shaped association was observed between BMI and risk of unintentional death. Both underweight and overweight were associated with increased mortality risk for all unintentional injuries and for subtype causes. Our study suggests that BMI might be a significant target for preventive interventions on deaths caused by unintentional injuries.

Risk Factors for Cardiovascular Disease, Metabolic Syndrome and Sleepiness in Truck Drivers

Background

Truck driver sleepiness is a primary cause of vehicle accidents. Several causes are associated with sleepiness in truck drivers. Obesity and metabolic syndrome (MetS) are associated with sleep disorders and with primary risk factors for cardiovascular diseases (CVD). We analyzed the relationship between these conditions and prevalence of sleepiness in truck drivers.

Methods

We analyzed the major risk factors for CVD, anthropometric data and sleep disorders in 2228 male truck drivers from 148 road stops made by the Federal Highway Police from 2006 to 2011. Alcohol consumption, illicit drugs and overtime working hours were also analyzed. Sleepiness was assessed using the Epworth Sleepiness Scale.

Results

Mean age was 43.1 ± 10.8 years. From 2006 to 2011, an increase in neck (p = 0.011) and abdominal circumference (p < 0.001), total cholesterol (p < 0.001), triglyceride plasma levels (p = 0.014), and sleepiness was observed (p < 0.001). In addition, a reduction in hypertension (39.6% to 25.9%, p < 0.001), alcohol consumption (32% to 23%, p = 0.033) and overtime hours (52.2% to 42.8%, p < 0.001) was found. Linear regression analysis showed that sleepiness correlated closely with body mass index (β = 0.19, Raj2 = 0.659, p = 0.031), abdominal circumference (β = 0.24, Raj2 = 0.826, p = 0.021), hypertension (β = -0.62, Raj2 = 0.901, p = 0.002), and triglycerides (β = 0.34, Raj2 = 0.936, p = 0.022). Linear multiple regression indicated that hypertension (p = 0.008) and abdominal circumference (p = 0.025) are independent variables for sleepiness.

Conclusions

Increased prevalence of sleepiness was associated with major components of the MetS.

Effect of weight, height and BMI on injury outcome in side impact crashes without airbag deployment

A comprehensive analysis is performed to evaluate the effect of weight, height and body mass index (BMI) of occupants on side impact injuries at different body regions. The accident dataset for this study is based on the National Automotive Sampling System-Crashworthiness Data System (NASS-CDS) for accident year 2000-08. The mean BMI values for driver and front passenger are estimated from all types of crashes using NASS database, which clearly indicates that mean BMI has been increasing over the years in the USA. To study the effect of BMI in side impact injuries, BMI was split into three groups namely (1) thin (BMI<21), (2) normal (BMI 24-27), (3) obese (BMI>30). For more clear identification of the effect of BMI in side impact injuries, a minimum gap of three BMI is set in between each adjacent BMI groups. Car model years from MY1995-1999 to MY2000-2008 are chosen in order to identify the degree of influence of older and newer generation of cars in side impact injuries. Impact locations particularly side-front (F), side-center (P) and side-distributed (Y) are chosen for this analysis. Direction of force (DOF) considered for both near side and far side occupants are 8 o'clock, 9 o'clock, 10 o'clock and 2 o'clock, 3 o'clock and 4 o'clock respectively. Age <60 years is also one of the constraints imposed on data selection to minimize the effect of bone strength on the occurrence of occupant injuries. AIS2+ and AIS3+ injury risk in all body regions have been plotted for the selected three BMI groups of occupant, delta-V 0-60kmph, two sets (old and new) of car model years. The analysis is carried with three approaches: (a) injury risk percentage based on simple graphical method with respect to a single variable, (b) injury distribution method where the injuries are marked on the respective anatomical locations and (c) logistic regression, a statistical method, considers all the related variables together. Lower extremity injury risk appears to be high for thin BMI group. It is found that BMI does not have much influence on head injuries but it is influenced more by the height of the occupant. Results of logistic analysis suggest that BMI, height and weight may have significant contribution towards side impact injuries across different body regions.

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≤19kg/m(2)) 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.

Relationship Between Obesity and Driving

Obesity, which has become epidemic throughout many parts of the world, is known to be a risk factor for a range of diseases including hypertension, diabetes, and vascular disease. Based on this review, it also appears that obesity is associated with increased crash risk and increased risk of serious or fatal injury in a crash. The problem is particularly an issue for commercial truck drivers. Data are presented showing the high prevalence of obesity in truck drivers. Inadequate sleep, poor nutrition, lack of exercise, and the sedentary nature of driving all contribute to the risk of obesity. The obesity related condition of obstructive sleep apnea (OSA) is known to increase crash risk. Treatment of this condition has been demonstrated to improve driving performance and to reduce crash risk. Screening truck drivers for obesity related health conditions, such as OSA, would be expected to result in public safety benefits.

Does Obesity Increase the Risk of Injury or Mortality in Motor Vehicle Crashes? A Systematic Review and Meta-Analysis

The objective of this review was to assess the risk of obesity in injuries and fatalities resulting from motor vehicle crash (MVC), as compared with individuals with a normal-range body mass index. A systematic review of the literature was conducted yielding 824 potential studies. Nine of these studies met our inclusion criteria. Meta-analyses examining obesity as a risk factor for various injury types and risk of fatality were conducted using data from these studies. Obesity was associated with higher fatality risk (odds ratio [OR] = 1.89, 95% confidence interval [CI] = 1.51-2.37, P = .0001; pooled estimate from 6 studies), and increased risk of lower extremity fractures (OR = 1.39, 95% CI = 1.18-1.65, P = .0001; pooled estimate from 2 studies). No significant differences were observed when considering abdominal injuries or pelvic fractures. Interestingly, for head injuries obesity was a protective factor (OR = 0.67, 95% CI = 0.46-0.97, P = .0001; pooled data from 3 studies). Evidence strongly supports the association of obesity with higher fatality and fractures of the lower extremities in MVCs. Contrary to our hypothesis, 3 studies showed that obesity was a protective factor in reducing head injuries. Furthermore, the review shows that obesity was not a risk factor of MVC-related pelvic fractures and abdominal injuries.

Time to death analysis of road traffic accidents in relation to delta V, drunk driving, and restraint systems

OBJECTIVE

The main goal of this research is to identify variables related to the expected time to death due to road traffic accidents (RTAs). Such research is expected to be useful in improving safety laws and regulations and developing new safety systems. The resulting information is crucial not only for reducing accident fatalities but for assessing related insurance policies.

METHODS

In this article, we analyze factors that are potentially associated with variation in the expected survival time after a road traffic accident using Weibull regression. In particular, we consider the association with alcohol involvement, delta V, and restraint systems.

RESULTS

Our empirical results, obtained based on the NASS-CDS, indicate that the expected survival time for non-alcohol-impaired drivers is 3.23 times longer at a delta V of 50 km/h than that for alcohol-impaired drivers under the same conditions. In addition, it was observed that, even when occupants were alcohol-impaired, if they were protected by both air bags and seat belts, their expected survival time after an RTA increased 2.59-fold compared to alcohol-impaired drivers who used only seat belts.

CONCLUSION

Our findings may be useful in improving road traffic safety and insurance policies by offering insights into the factors that reduce fatalities.

Adolescence BMI and trends in adulthood mortality: a study of 2.16 million adolescents

CONTEXT

The consequence of elevated body mass index (BMI) at adolescence on early adulthood mortality rate and on predicted life expectancy is unclear.

OBJECTIVE

The objective of the investigation was to study the relationship between BMI at adolescence and mortality rate as well as the mortality trend over the past 4 decades across the entire BMI range.

DESIGN AND SETTING

The study included a nationwide longitudinal cohort.

PARTICIPANTS

A total of 2 159 327 adolescents (59.1% males) born between 1950 and 1993, who were medically evaluated for compulsory military service in Israel, participated in the study.

INTERVENTIONS

Height and weight were measured at age 17 years, and BMI was stratified based on the Centers for Disease Control and Prevention-established percentiles for age and sex.

MAIN OUTCOME MEASURE

Incident cases of all-cause mortality before age 50 years were recorded. Cox-proportional hazard models were used to assess mortality rates and its trend overtime.

RESULTS

During 43 126 211 person-years of follow-up, 18 530 deaths were recorded. As compared with rates observed in the 25th to 50th BMI percentiles, all-cause mortality continuously increased across BMI range, reaching rates of 8.90/10(4) and 2.90/10(4) person-years for men and women with BMI greater than the 97th percentile, respectively. A multivariate analysis adjusted for age, socioeconomic status, education, and ethnicity demonstrated a significant increase in mortality at BMI greater than the 50th percentile (BMI > 20.55 kg/m(2)) for men and the 85th percentile or greater in women (BMI > 24.78 kg/m(2)). During the last 4 decades, a significant decrease in mortality rates was documented in normal-weight participants born between 1970 and 1980 vs those born between 1950 and 1960 (3.60/104 vs 4.99/10(4) person-years, P < .001). However, no improvement in the survival rate was observed among overweight and obese adolescents during the same time interval. Significant interaction between BMI and birth year was observed (P = .007).

CONCLUSIONS

BMI at adolescence, within the normal range, is associated with all-cause mortality in adulthood. Mortality rates among overweight and obese adolescents did not improve in the last 40 years, suggesting that preadulthood obesity may attenuate the progressive increase in life expectancy.

Complex Interaction between Obesity and Trauma

Trauma and obesity are large-scale epidemics that can be associated with significant morbidity and mortality. In few studies, it has noted that there is the ‘obesity paradox’ (obesity has been found to be protective against mortality) due to certain causes, i.e. heart failure or cardiovascular disease. Subcutaneous fat can show great variability between individuals and increased subcutaneous fat may be protective against injuries by cushioning the internal abdominal organs against injurious forces in road traffic accidents. Many factors including the body fat distribution, body shape, and center of gravity may play an important role in the different injury patterns and severity of injury between men and women. A better understanding of how obesity influences trauma related injuries not only will help to improve the outcome but also foster the development of interventions to address the most salient and modifiable risk factors to reduce obesity related morbidity and mortality. In present article, we review the relevant literature with special considerations to understand the interactions of obesity and trauma with their impact on patient management and outcomes.

How to cite this article

Agrawal A. Complex Interaction between Obesity and Trauma. Panam J Trauma Crit Care Emerg Surg 2014;3(3):109-113.

The Relationship between Waist Circumference and Work-related Injury in Reference to the Fourth Korea National Health and Nutrition Examination Survey

Objective

This study aims to investigate the relationship between waist circumference and work-related injury in reference to the fourth Korea National Health and Nutrition Examination Survey.

Methods

By analyzing data from the fourth Korea National Health and Nutrition Examination Survey conducted from 2007 to 2009, we estimated the rate of injury experience according to socioeconomic status, including occupational property, of 8,261 subjects. We performed logistic regression analysis with work-related injury experience rate as dependent variable and waist circumference as an independent variable, Odds ratios (OR) were calculated, which reflect the likelihood of work-related injury experience rate, and 95% confidence interval (95% CI) while controlling for relevant covariates with stratifying by sex, age, nature of injury, site of injury and occupational group.

Results

Among 797 persons who had injury experience over the past 1 year, 293 persons (36.8%) had work-related injury experience. After adjusting the confounding variables, the work-related injury was related to abnormal waist circumference (OR = 1.35; 95% CI: 1.02 ~ 1.78). In subgroups, ORs were higher in men (OR = 1.42; 95% CI: 1.02 ~ 1.98), professional, manager, and administrator (OR = 2.41; 95% CI: 1.10 ~ 5.28). Higher rate of injuries were noted in back and waist (OR = 2.92; 95% CI: 1.49 ~ 5.73), and transport accident had increased risk (OR = 1.60; 95% CI: 1.13 ~ 2.28).

Conclusions

Work-related injury rate differed depending on the waist circumference. The abdominal obesity was associated with higher risk of work-related injury. This study would be useful in selecting appropriate priorities for work-related injury management in Korea.

Effects of BMI on the risk and frequency of AIS 3+ injuries in motor-vehicle crashes

OBJECTIVE

Determine the effects of BMI on the risk of serious-to-fatal injury (Abbreviated Injury Scale ≥ 3 or AIS 3+) to different body regions for adults in frontal, nearside, farside, and rollover crashes.

DESIGN AND METHODS

Multivariate logistic regression analysis was applied to a probability sample of adult occupants involved in crashes generated by combining the National Automotive Sampling System (NASS-CDS) with a pseudoweighted version of the Crash Injury Research and Engineering Network database. Logistic regression models were applied to weighted data to estimate the change in the number of occupants with AIS 3+ injuries if no occupants were obese.

RESULTS

Increasing BMI increased risk of lower-extremity injury in frontal crashes, decreased risk of lower-extremity injury in nearside impacts, increased risk of upper-extremity injury in frontal and nearside crashes, and increased risk of spine injury in frontal crashes. Several of these findings were affected by interactions with gender and vehicle type. If no occupants in frontal crashes were obese, 7% fewer occupants would sustain AIS 3+ upper-extremity injuries, 8% fewer occupants would sustain AIS 3+ lower-extremity injuries, and 28% fewer occupants would sustain AIS 3+ spine injuries.

CONCLUSIONS

Results of this study have implications on the design and evaluation of vehicle safety systems.

Impact speed and a pedestrian's risk of severe injury or death

This study estimates the risk of severe injury or death for pedestrians struck by vehicles using data from a study of crashes that occurred in the United States in years 1994-1998 and involved a pedestrian struck by a forward-moving car, light truck, van, or sport utility vehicle. The data were weighted to correct for oversampling of pedestrians who were severely injured or killed. Logistic regression was used to adjust for potential confounding related to pedestrian and vehicle characteristics. Risks were standardized to represent the average risk for a pedestrian struck by a car or light truck in the United States in years 2007-2009. Results show that the average risk of a struck pedestrian sustaining an injury of Abbreviated Injury Scale 4 or greater severity reaches 10% at an impact speed of 17.1miles per hour (mph), 25% at 24.9mph, 50% at 33.0mph, 75% at 40.8mph, and 90% at 48.1mph. The average risk of death reaches 10% at an impact speed of 24.1mph, 25% at 32.5mph, 50% at 40.6mph, 75% at 48.0mph, and 90% at 54.6mph. Risks varied by age. For example, the average risk of death for a 70-year-old pedestrian struck at any given speed was similar to the average risk of death for a 30-year-old pedestrian struck at a speed 11.8mph faster.

Obesity is associated with the future risk of heavy truck crashes among newly recruited commercial drivers

This study estimates the dose-response relationship between body mass index (BMI) and crash risk in operators of heavy commercial motor vehicles. Intake data were collected during the first two weeks of instruction from 744 new truck drivers training for their commercial driver's licenses at a school operated by the cooperating trucking firm. Drivers were then followed prospectively on the job using the firm's operational data for two years, or until employment separation, whichever came first. Multivariate Poisson regression and Cox proportional hazards models were used to estimate the relationship between crash risk and BMI, controlling for demographic characteristics and for variations in the exposure to risks on the road. Results from the Poisson regression, which used cumulative miles driven as an exposure control, indicated that compared to normal BMI (18.5<BMI<25) the risk ratio (RR) for all crashes was significantly higher for drivers in the combined obesity Classes II and III: RR=1.55 (95% CI 1.24-1.94). Similarly, the multivariate Cox proportional hazard model (controlling for miles and job type on a week-by-week basis) showed that crash risk was significantly higher compared to normal BMI for the same combined obesity Classes II and III: RR=1.54 (95% CI 1.13-2.10). The results of this prospective study establish an association between obesity and crash risk and have important implications for driver health and public safety.

A computational study of injury severity and pattern sustained by overweight drivers in frontal motor vehicle crashes

The objective of this study was to examine the role of body mass and subcutaneous fat in injury severity and pattern sustained by overweight drivers. Finite element models were created to represent the geometry and properties of subcutaneous adipose tissue in the torso with data obtained from reconstructed magnetic resonance imaging data-sets. The torso adipose tissue models were then integrated into the standard multibody dummy models together with increased inertial parameters and sizes of the limbs to represent overweight occupants. Frontal crash simulations were carried out considering a variety of occupant restraint systems and regional body injuries were measured. The results revealed that differences in body mass and fat distribution have an impact on injury severity and pattern. Even though the torso adipose tissue of overweight subjects contributed to reduce abdominal injury, the momentum effect of a greater body mass of overweight subjects was more dominant over the cushion effect of the adipose tissue, increasing risk of other regional body injuries except abdomen. Through statistical analysis of the results, strong correlations (p < 0.01) were found between body mass index and regional body injuries except neck injury. The analysis also revealed that a greater momentum of overweight males leads to greater forward torso and pelvic excursions that account for higher risks (p < 0.001) of head, thorax and lower extremity injury than observed in non-overweight males. The findings have important implications for improving the vehicle and occupant safety systems designed for the increasing global obese population.