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.     

The analysis of group truncated binary data with random effects: injury severity in motor vehicle accidents

The analysis of group truncated binary data has been previously considered by O'Neill and Barry (1995b, Biometrics 51, 533-541), where the analysis assumed that responses within each group were independent. In this paper, we consider the analysis of such data when there is group-level heterogeneity. A generalized linear mixed model is hypothesized to model the response and maximum likelihood estimates are derived for the truncated case. A score test is derived to test for heterogeneity. Finally, the method is applied to a set of traffic accident data.     

Self-harm and risk of motor vehicle crashes among young drivers: findings from the DRIVE Study

Background

Some motor vehicle crashes, particularly single-vehicle crashes, may result from intentional self-harm. We conducted a prospective cohort study to assess the risk that intentional self-harm poses for motor vehicle crashes among young drivers.

Methods

We prospectively linked survey data from newly licensed drivers aged 17–24 years to data on licensing attempts and police-reported motor vehicle crashes during the follow-up period. We investigated the role of recent engagement in self-harm on the risk of a crash. We took into account potential confounders, including number of hours of driving per week, psychological symptoms and substance abuse.

Results

We included 18 871 drivers who participated in the DRIVE Study for whom data on self-harm and motor vehicle crashes were available. The mean follow-up was 2 years. Overall, 1495 drivers had 1 or more crashes during the follow-up period. A total of 871 drivers (4.6%) reported that they had engaged in self-harm in the year before the survey. These drivers were at significantly increased risk of a motor vehicle crash compared with drivers who reported no self-harm (relative risk [RR] 1.42, 95% confidence interval [CI] 1.15–1.76). The risk remained significant, even after adjustment for age, sex, average hours of driving per week, previous crash, psychological distress, duration of sleep, risky driving behaviour, substance use, remoteness of residence and socio-economic status (RR 1.37, 95% CI 1.09–1.72). Most of the drivers who reported self-harm and had a subsequent crash were involved in a multiple-vehicle crash (84.1% [74/88]).

Interpretation

Engagement in self-harm behaviour was an independent risk factor for subsequent motor vehicle crash among young drivers, with most crashes involving multiple vehicles.Globally, poor mental health and injuries (including suicide) are ranked as the first and second highest contributors of lost disability-adjusted life-years among young people.¹ Self-harm and suicide attempts are reported by 5%–17% of people aged 14–25 years and may be increasing in prevalence.^2–5 Self-harm refers to the deliberate injuring of oneself through such methods as superficial cutting, attempted hanging and poisoning.⁶ Self-harm is performed most often by people with mental health problems and is a risk factor for suicide and other causes of death.^6–8 Reasons for this behaviour are not well known. They may include coping with feelings of distress, suicidal intent, crying out for attention, addictive self-mutilation, impulsive behaviour, self-loathing and punishment, and attempting to feel in control. A recent study found the rate ratio of self-harm to suicide to be 36 (95% confidence interval [CI] 34.9–37.1).⁹The rate of death from motor vehicle crashes is hypothesized to be increased among individuals who have previously attempted suicide, and crashes are implicated as a mode of self-harm.^8,10,11 There are several possible reasons for this increased risk of crash-related injury and death. For example, individuals who self-harm may deliberately attempt to injure or kill themselves using a motor vehicle. Alternatively, an increased risk of crash may occur through an indirect association of self-harm with other risk factors associated with crashes. Poor mental health for example is associated with self-harm and has been linked to higher rates of crashes.⁸ Common symptoms of poor mental health include depressed or anxious mood, disturbed sleep and poor concentration, all of which may impair cognitive and psychomotor function and thereby impair a person’s ability to drive.¹² Self-harm is also commonly associated with alcohol and other substance use, which are also risk factors for motor vehicle crashes.^2,13,14 Finally, developmentally young adults and people who self-harm have poor impulse control, which suggests that they may be particularly vulnerable to a range of health risks, including accidental injury.^6,15,16Most studies of motor vehicle crashes among people who self-harm recruited patients seeking health services and used linked data from death registers to examine fatal outcomes. We conducted a prospective study to examine self-harm as a risk factor for nonfatal motor vehicle crashes. We used a cohort of young drivers of whom a subset engaged in self-harm. We also explored the role of associated risk factors, including symptoms of mental disorder and substance use, in explaining any difference in rates of crash.     

Robust human body model injury prediction in simulated side impact crashes

This study developed a parametric methodology to robustly predict occupant injuries sustained in real-world crashes using a finite element (FE) human body model (HBM). One hundred and twenty near-side impact motor vehicle crashes were simulated over a range of parameters using a Toyota RAV4 (bullet vehicle), Ford Taurus (struck vehicle) FE models and a validated human body model (HBM) Total HUman Model for Safety (THUMS). Three bullet vehicle crash parameters (speed, location and angle) and two occupant parameters (seat position and age) were varied using a Latin hypercube design of Experiments. Four injury metrics (head injury criterion, half deflection, thoracic trauma index and pelvic force) were used to calculate injury risk. Rib fracture prediction and lung strain metrics were also analysed. As hypothesized, bullet speed had the greatest effect on each injury measure. Injury risk was reduced when bullet location was further from the B-pillar or when the bullet angle was more oblique. Age had strong correlation to rib fractures frequency and lung strain severity. The injuries from a real-world crash were predicted using two different methods by (1) subsampling the injury predictors from the 12 best crush profile matching simulations and (2) using regression models. Both injury prediction methods successfully predicted the case occupant's low risk for pelvic injury, high risk for thoracic injury, rib fractures and high lung strains with tight confidence intervals. This parametric methodology was successfully used to explore crash parameter interactions and to robustly predict real-world injuries.     

The relationships among the severity of spinal cord injury,motor and somatosensory evoked potentials and spinal cord blood flow

To characterize the changes in axonal function in the motor and somatosensory tracts of the cord after spinal cord injury (SCI) and to correlate these changes with spinal cord blood flow (SCBF), the relationships among the severity of SCI, motor and somatosensory evoked potentials (MEPs and SSEPs) and SCBF were examined. Fifteen rats received a 1.5 g (n = 5), 20 g (n = 5) or 56 g (n = 5) clip compression injury of the cord at C8. SCBF at the injury site was measured by the hydrogen clearance technique 35 min before and 30 min after SCI. Concomitantly MEPs from the cord at T10 (MEP-C) and from the sciatic nerve (MEP-N) and SSEPs were recorded.A linear relationship (r = −0.89, P < 0.002) was found between the severity of SCI and the reduction in SCBF at the injury site. Linear discriminant analysis revealed that both the MEP (P < 0.0001) and SSEP (P < 0.003) were significantly related to the severity of SCI. Furthermore, the amplitude of the MEP (r = 0.65, P < 0.0001) and SSEP (r = 0.58, P < 0.0011) was significantly correlated with the posttraumatic SCBF. Multiple regression revealed that both the severity of cord injury and the degree of posttraumatic ischemia were significantly related to axonal dysfunction after SCI. While the MEP was more sensitive to injury than the SSEP, the SSEP more accurately distinguished between mild and moderate severities of cord injury.Axonal conduction in the motor and somatosensory tracts of the cord was significantly correlated with the reduction in posttraumatic SCBF and, therefore, these data provide quantitative evidence linking posttraumatic ischemia to axonal dysfunction following acute cord injury. Furthermore, this study validates the hypothesis that the combined recording of MEPs and SSEPs is an accurate technique to assess the physiological integrity of the cord after injury.     

Activity-related changes of body fat and motor performance in obese seven-year-old boys

The effects of 35 weeks of extra-curricular, mainly aerobic, dynamic physical activity were analysed in overweight and obese 7-year-old boys contrasted with control groups. Body composition was estimated by using the body mass index (BMI) and skinfold thicknesses. Overweight or obesity was defined according to the suggestions of Cole and associates (2000). The activity program consisted of swimming and water games, folk dance, and soccer. Data were collected four times between September 2003 and October 2004. Thirty-one overnight or obese boys volunteered to participate in the activity program (weekly, to physical classes of 45 min. plus three extra-curricular activity sessions of 60 min. duration). The control subjects were 43 overweight or obese boys, and 75 non-overweight and non-obese ones. The controls had only two curricular physical education classes every week. Physical performance capacity was tested by 30 m dash, 400 m run, standing long jump, and fist-ball throw. Body fat content estimated by taking the sum of five skinfolds decreased significantly during the 35-week training program. However, body weight as well as skinfold thicknesses increased significantly during the four month non-active period that followed. Physical performance improved during the test period, but deteriorated between the third and fourth data collections. BMI, as well as the sum of five skinfolds increased in both control groups.Physical performance decreased in the overweight control subjects and increased moderately in the non obese ones. We inferred that more vigorous habitual exercise alone, i.e., without a program of dietary control, though effective, could not efficiently stabilise body fat, still less achieve a lasting reduction of it. Obese, but also overweight subjects need long term exercise programs of sufficient intensity, duration and frequency, plus dietary measures, to get rid of excess body fat.     

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.     

Injuries associated with mandible fractures sustained in motor vehicle collisions

Motor vehicle collisions are second only to altercations as the most common cause of mandible fractures. This article details in a retrospectively studied group the incidence of isolated mandible fractures and associated injuries in patients who were involved in motor vehicle collisions. This group consisted of 148 patients with mandible fractures listed in the University of Mississippi's trauma registry during the past 5 years. In almost all patients, associated injuries occurred with mandible fractures that were caused by motor vehicle collisions, with an incidence of 99.3 percent. Facial and head lacerations and facial fractures were the leading associated injuries, occurring in more than half of the patients who had a mandible fracture. Closed head injury is the major life-threatening associated injury and cause of mortality. The life-threatening injuries occurred in 64.8 percent of patients in this study. The mortality rate in this group of patients was 8.1 percent. These data suggest that mandible fractures from motor vehicle collisions should never be viewed as an isolated injury but rather as part of a spectrum of significant and sometimes life-threatening injuries that require thorough trauma evaluation at the time of presentation.     

Effect of environmental factors on risk of injury of child pedestrians by motor vehicles: a case-control study.

OBJECTIVE--To identify and assess contribution of environmental risk factors for injury of child pedestrians by motor vehicles. DESIGN--Community based case-control study. Environmental characteristics of sites of child pedestrian injury were compared with the environmental characteristics of selected comparison sites. Each comparison site was the same distance and direction from home of control child as was the injury site from home or relevant case child. Two control sites were selected for each injury site. SETTING--Auckland region of New Zealand. SUBJECTS--Cases were 190 child pedestrians aged < 15 who were killed or hospitalised after collision with a motor vehicle on a public road during two years and two months. Controls were 380 children randomly sampled from population and frequency matched for age and sex. MAIN OUTCOME MEASURE--Traffic volume and speed and level of parking on curbs at injury sites and comparison sites. RESULTS--Risk of injury of child pedestrians was strongly associated with traffic volume: risk of injury at sites with highest traffic volumes was 14 times greater than that at least busy sites (odds ratio 14.30; 95% confidence interval 6.98 to 29.20), and risk increased with increasing traffic volume. High density of curb parking was also associated with increased risk (odds ratio 8.12; 3.32 to 19.90). Risk was increased at sites with mean speeds over 40 km/h (odds ratio 2.68; 1.26 to 5.69), although risk did not increase further with increasing speed. CONCLUSION--Reducing traffic volume in urban areas could significantly reduce rates of child pedestrian injury. Restricting curb parking may also be effective.     

Angeli's salt and spinal motor neuron injury

Nitroxyl anion or its conjugate acid (NO_-/HNO) and nitric oxide (NO) may both have pro-oxidative and cytotoxic properties. Superoxide dismutase (SOD) enzyme has been shown to convert reversibly HNO to NO. Mutations found in the SOD enzyme in some familial amyotrophic lateral sclerosis (ALS) patients affect redox properties of the SOD enzyme in a manner, which may affect the equilibrium between NO and HNO. Therefore, we studied the effects of HNO releasing compound, Angeli's salt (AS), on both motor and sensory functions after intrathecal administration in the lumbar spinal cord of a male rat. These functions were measured by rotarod, spontaneous activity, paw- and tail-flick tests. In addition, we compared the effect of AS to NO releasing papanonoate, old AS solution and sulphononoate in the motor performance test. The effect of intrathecal delivery of AS on the markers of the spinal cord injury and oxidative/nitrosative stress were further studied.

Results: Freshly prepared AS (5 or 10 μmol), but not papanonoate, caused a marked decrease in the rotarod performance 3-7 days after the intrathecal administration. The peak motor deficiency was noted 3 days after AS (5 μmol) delivery. Old, degraded, AS solution and nitrous oxide releasing sulphononoate did not decrease motor performance in the rotarod test. AS did not affect the sensory stimulus evoked responses as measured by the paw-flick and tail-flick tests. Immunohistological examination revealed that AS caused injury related changes in the expression of glial fibrillary acidic protein (GFAP), fibroblast growth factor (FGF-2) and laminins in the spinal cord. Moreover, AS increased nitrotyrosine immunoreactivity in the spinal motor neurons.

Therefore, we conclude that AS, but not NO releasing papanonoate, causes motor neuron injury but does not affect the function of sensory nerves in behavioural tests.     

Risk ratios for obesity in families of obese African-American and Caucasian women

We examined age- and sex-standardized risk ratios (SRRs) in matched samples of 1,185 families of obese African-American and Caucasian women. Familial risk ratios increased with body mass index (BMI) of proband and BMI thresholds of relative. Ratios were higher in Caucasian than African-American families, apparently because Caucasian probands were more extreme relative to their population mean. Risk ratios for moderate obesity (BMI >/= 30) were around 2 for African-Americans and were a little higher in Caucasians. Ratios for extreme obesity (BMI >/= 40) ranged from 3 to 5 in African-Americans and from about 5 to 9 in Caucasians. Thin relatives were rare in families of both races. Risk ratios appear high enough in both racial groups to facilitate the identification of quantitative trait loci underlying common obesity phenotypes. The high population prevalence of obesity in African-American women will require particularly high selection thresholds to achieve risk ratios comparable to those for Caucasians. The scarcity of thin siblings in both groups will greatly increase the effort required in sample recruitment for discordant pair designs.     

The psychophysiology of motor vehicle accident related posttraumatic stress disorder

Heart rate, BP, and electrodermal responses of four individuals with PTSD secondary to motor vehicle accidents (MVAs) were measured while they imagined two separate scenes related to their MVA. Results showed reliable HR responses to these images. In addition, SBP and DBP also showed some responsivity to the images while skin resistance level changed reliably in only 2 of 4 subjects. Psychophysiological measurement could play a role in the assessment and treatment of MVA-related PTSD.     

Genioglossus muscle activity and serotonergic modulation of hypoglossal motor output in obese Zucker rats.

Obese Zucker rats have a narrower and more collapsible upper airway compared with lean controls, similar to obstructive sleep apnea (OSA) patients. Genioglossus (GG) muscle activity is augmented in awake OSA patients to compensate for airway narrowing, but the neural control of GG activity in obese Zucker rats has not been investigated to determine whether such neuromuscular compensation also occurs. This study tests the hypotheses that GG activity is augmented in obese Zucker rats compared with lean controls and that endogenous 5-hydroxytryptamine (5-HT) contributes to GG activation. Seven obese and seven lean Zucker rats were implanted with electroencephalogram and neck muscle electrodes to record sleep-wake states, and they were implanted with GG and diaphragm wires for respiratory muscle recordings. Microdialysis probes were implanted into the hypoglossal motor nucleus for perfusion of artificial cerebrospinal fluid and the 5-HT receptor antagonist mianserin (100 microM). Compared with lean controls, respiratory rates were increased in obese rats across sleep-wake states (P=0.048) because of reduced expiratory durations (P=0.007); diaphragm activation was similar between lean and obese animals (P=0.632). Respiratory-related, tonic, and peak GG activities were also similar between obese and lean rats (P>0.139). There was no reduction in GG activity with mianserin at the hypoglossal motor nucleus, consistent with recent observations of a minimal contribution of endogenous 5-HT to GG activity. These results suggest that despite the upper airway narrowing in obese Zucker rats, these animals have a sufficiently stable airway such that pharyngeal muscle activity is normal across sleep-wake states.     

Posttraumatic growth,posttraumatic stress disorder and resilience of motor vehicle accident survivors

Background  

Although some previous studies have suggested that posttraumatic growth (PTG) is comprised of several factors with different properties, few have examined both the association between PTG and posttraumatic stress disorder (PTSD) and between PTG and resilience, focusing on each of the factors of PTG. This study aimed to examine the hypothesis that some factors of PTG, such as personal strength, relate to resilience, whereas other factors, such as appreciation of life, relate to PTSD symptoms among Japanese motor vehicle accident (MVA) survivors.