Injury Prevention

Arlene I. Greenspan, Matthew Breiding, and Joanne Klevens

OVERVIEW

Traumatic brain injury (TBI) is a major cause of death and disability. TBI may be unintentional, due to assault, or self-inflicted. The distribution of causes for TBI varies by demographic characteristics (e.g., age). Prevention strategies should target those at greatest risk. For example, among children ages 0 to 4 years old, assault accounts for 42.9% of all TBI-related deaths, followed by motor vehicle crashes (29.2%); for youth and young adults’ motor vehicles are the main cause of TBI-related death, and account for 55.8% of TBI deaths in those ages 5 to 14 years old and 47.4% of TBI deaths for those ages 15 to 24 years old; for adults 65 years and older, falls are the leading cause of TBI-related death [1]. This chapter focuses on prevention strategies for TBI due to transportation, falls, and assault, though epidemiology will also be touched upon as it relates to the rationale for selected preventive strategies.

TRANSPORTATION-RELATED TBI

Definition/Mechanism

The broad-term transportation injuries typically includes injuries that involve single or multiple vehicle motor vehicle crashes, motorcycle crashes, other modes of transportation including bicycles, and pedestrian injuries involving a motor vehicle or other mode of transportation. During a transportation crash, brain injury can occur through direct contact with a hard surface such as the steering wheel or the ground, or by rapid rotation of the brain inside the skull. The severity of TBI may vary from minor concussions to severe intracranial injury or death.

Epidemiology

Motor vehicle crashes are a leading cause of TBI-related death in the United States and are over-represented as a cause of severe TBI. From 2006 to 2010, 26% of all TBI-related deaths were due to motor vehicle-related crashes. This translates to more than 13,500 motor vehicle-related TBI deaths each year [1]. Motor vehicle-related deaths due to TBI disproportionately affect children and young adults, accounting for more than half of all TBI-related deaths in children ages 5 to 14 years old (56%), close to half of all TBI-related deaths in adolescents and young adults (47%) ages 15 to 24 years old, 29% of TBI-related deaths for people ages 25 to 44 years old, and 23% of deaths for those 45 to 64 years old [1]. Risk for sustaining a TBI in a motor vehicle crash increases for older adults, who are at greater risk for intracranial bleeding compared to their younger counterparts [2–4]. Motor vehicle crashes also result in a substantial number of nonfatal TBIs each year. Data from 2006 to 2010 reveal that close to 250,000 people were seen annually in emergency departments (EDs) for TBI following a motor vehicle crash [1].

Etiology

Risk factors that increase the probability of sustaining a TBI following a motor vehicle crash include the type of road user (e.g., motor vehicle occupant, motorcyclist, bicyclist, pedestrian), crash severity, type of crash (e.g., frontal, side, rollover crash), protective equipment used (e.g., seat belts, airbags, helmets), and individual factors (e.g., age).

Studies have demonstrated that vulnerable road users such as pedestrians, bicyclists, and motorcyclists have a higher probability of sustaining a TBI compared with vehicle occupants [5,6]. Vulnerable road users lack the protection of the vehicle and often collide with an object of greater mass that may be traveling at greater speed (e.g., pedestrian or cyclists colliding with a moving car). Pedestrians are at greatest risk for severe TBI, followed by moped riders, and cyclists [6].

Among motor vehicle occupants, two factors that influence the risk of sustaining a TBI following a motor vehicle crash are the type and severity of the crash. The greatest number of severe TBIs is seen following side-impact crashes, and the greatest number of concussions is observed following frontal crashes [7]. The risk for sustaining a severe TBI or skull fracture, however, is greatest for persons involved in rollover crashes, followed by side-impact crashes. Rear-impact crashes are associated with the lowest risk for severe TBI.

Change in velocity (Delta V) is often used as a measure of crash severity. It is calculated as the change in vehicle velocity for the duration of the crash event. As Delta V increases, so does risk for TBI. Although the risk for severe TBI increases with increasing Delta V, even at low speeds concussions can occur [6].

Physiologic changes to the brain as individuals age result in increased risk for intracranial bleeding, especially subdural hematoma [8]. Older adults, therefore, have increased risk for developing intracranial bleeding if involved in an occupant-related [2,3] or pedestrian [4] motor vehicle crash.

Prevention Strategies

Seat belt use is the most effective means for reducing deaths and injuries from a motor vehicle crash [9]. The National Highway Traffic Safety Administration (NHTSA) reports that use of seat belts reduces risk of death by 45% and serious injury by 50% for drivers and front seat passenger in all types of crashes [10]. NHTSA estimates that from 1975 to 2008, 255,000 lives were saved due to seat belts [10]. One study found that 4.1% of seat belt users sustained a TBI following a motor vehicle crash compared to 10.4% of nonusers [11]. Another study found that seat belt use reduced the risk of severe TBI by about 75% and skull fracture by 73% [7]. Seat belt laws have increased seat belt use, and primary laws are more effective than secondary laws [12]. Primary laws allow police officers to issue citations for occupants who are not wearing a seat belt. Secondary laws only allow a police officer to issue a citation for not wearing a seat belt if the driver is pulled over for another infraction. States with primary laws have seat belt use rates that on average are 9% higher than states with secondary laws [13]. In addition to seat belt laws, Click It or Ticket activities increase median seat belt use by 16% [12].

Among infants and children, age and size-appropriate car seats reduce the risk of death or injury, including TBI. One study that examined the factors associated with TBI among children involved in motor vehicle crashes found that unrestrained children were three times more likely to sustain a TBI than children who were in age-appropriate car seats [14]. Another [15] found that 4- to 8-year-old children restrained in adult seat belts were twice as likely to sustain a TBI as children restrained in appropriate child car seats. According to NHTSA, use of rear-facing infant seats reduces risk of death by 71% for infants up to 1 year of age and by 54% for use of child car seats among toddlers ages 2 to 4 years old [10]. In addition, compared to adult seat belts, use of booster seats among children 4 to 8 years old reduces the risk of serious injury by 45% [15]. In 2011, the American Academy of Pediatrics (AAP) updated their recommendations regarding the use of infant and child car seats [16]. AAP recommends that infants and young children remain in rear-facing infant/car seats until 2 years of age or until they reach the height and weight limit of their car seat. From age 2 until at least 5 years of age (or until they reach the height and weight limits on their car seats), children should be restrained in forward-facing car seats. Once children outgrow their child safety seats, they need to start using booster seats (about age 5 years), until they can appropriately fit into an adult seat belt. Children can usually fit into an adult seat belt when they are approximately 57-in. tall [16]. Results from a Community Guide systematic review on interventions to increase child safety seat use found strong evidence for the effectiveness of child safety seat laws [17]. Although the Community Guide found insufficient evidence that education programs alone increased child safety seat use, education programs paired with car seat distribution or incentives to buy car seats resulted in increased car seat use [17].

Airbags, when used in combination with seat belts, provide added protection compared to seat belts alone [18]. Head-protecting side airbags reduce the risk of TBI by 30% to 37% [19,20]. Note that while frontal airbags protect adults from injury when deployed in a crash, a deployed frontal airbag can kill infants and children if seated in front of an airbag; they are especially harmful for infants/children in rear-facing infant/car seats. Children 12 years old and younger should always be restrained in the back seats [21].

According to NHTSA, TBI is the most common cause of death following a motorcycle crash [22]. Motorcycle riders who do not wear helmets are 40% more likely to die from TBI [22]. Wearing a motorcycle helmet reduces the risk of death from TBI by 42% and reduces the risk of nonfatal TBI by 69% [23]. Laws that require use of motorcycle helmets are an effective means for increasing helmet use [22]. Currently, 19 states have motorcycle helmet laws that require all riders to be helmeted. An additional 28 states have laws that require some riders to be helmeted, and three states (Illinois, New Hampshire, and Iowa) do not have any laws governing helmet use [24].

Multiple studies over the past 30 years have demonstrated the effectiveness of bicycle helmets in reducing the risk of TBI, despite some controversy regarding the magnitude of the effect [25–28]. The effectiveness of bicycle helmets has been demonstrated among all age groups, in crashes with and without motor vehicle involvement, and in various regions [25–28]. While helmets may be an effective method for preventing TBI in the event of a crash, other prevention strategies, such as creating bicycle paths that separate cyclists from motorists, can further reduce risk for injury [29].

FALL-RELATED TBI

Definition/Mechanism

When discussing falls, it is important to distinguish between falls from a height and falls at ground level. Some common activities that lead to falls from heights include falls from playground equipment, windows, ladders, or animals (e.g., horses), as well as falls downstairs. Ground-level falls may occur due to stumbling, tripping, or slipping while engaged in a variety of activities ranging from standing still to participation in sports or recreational activities. While epidemiological data have shed light on the incidence of fall-related TBI, much of the work identifying risk factors and prevention strategies has focused on falls in general or injuries resulting from falls.

Epidemiology

From 2006 to 2010, falls were the leading cause of TBI-related ED visits, when the cause was documented, among all age groups combined (43.5%), but particularly among those 0 to 4 years old (72.8%) and those 65 years of age and older (81.8%) [1]. Falls accounted for 24.7% of TBI-related hospitalizations for all ages combined; among those 0 to 4 years old falls accounted for 46.2% and for those 65 years of age and older, 37.7% [1]. Falls were also the leading cause of TBI-related deaths among those 65 years of age and older (54.4%) [1]. There is growing concern that the number of fall-related TBIs among those 65 years of age and older will increase in the coming years due to the aging of the U.S. population.

Etiology

Falls Among Older Adults

An Australian study of TBIs among those over the age of 65 found that the majority of fall-related TBIs (64.2%) were due to slipping, tripping, stumbling, or colliding with another person; 16.6% were due to falls downstairs; 10.2% were due to falls involving furniture, and 4.1% were due to falling off of ladders or scaffolds [30]. A literature review identified a number of risk factors for falls among older adults, including: advanced age; having a gait or balance disorder; poor lower extremity strength; dizziness; impaired cognition; cardiovascular disease; dementia; and depression [31]. Finally, particular medications, home conditions (e.g., poor lighting and loose rugs), and certain types of footwear have all been shown to influence the risk of falls among older adults.

Falls Among Children and Adolescents

In a study of children 0 to 5 years old who were hospitalized due to falls from either furniture or stairs, those who fell from stairs were significantly more likely to sustain injuries to their heads (64.3%), compared to falls from furniture (38.1%) [32]. An Australian study examining TBI in children 0 to 3 years old found that the leading causes of fall-related TBI were falls from furniture, falls while standing, and falls after being dropped by an adult, with the latter cause particularly prominent among those 0 to 6 months old [33]. Another study examined fall-related hospitalizations among adolescents ages 10 to 19 and found that among TBI-related hospitalizations caused by falls, 28% could be classified as sport-related [34]. A number of studies have examined the role of direct adult supervision and found a positive relationship between more adult supervision and reduced injury among children [35].

Falls Among Other Age Groups

Among adults 60 and younger, 64% were due to a fall from a height, with 27% due to a fall downstairs, and 15% due to a fall from a ladder; alcohol was a potential contributing factor in 30% of fall-related TBIs in this age group [36].

Prevention Strategies

There has been a significant amount of research examining the prevention of falls in the elderly and quite a few efficacious preventive interventions have been identified. Multicomponent physical exercise programs, particularly those that include balance retraining and muscle strengthening, have been shown to significantly reduce the risk of falls among the elderly living in the community [37]. Tai chi, which includes both strength and balance training, has been identified as a specific exercise program with beneficial effects [37]. Vitamin D supplementation has been shown to have positive benefits, but only for those with low levels of Vitamin D [37]. Surgical interventions, such as pacemakers and cataract surgery, have been found to reduce the rate of falls among those that are in need of these interventions [37]. Interventions in which home hazards are reduced have been shown to be effective in reducing fall risk [37]. Finally, prevention programs focused on multiple efficacious interventions, often tailored to an individual’s unique risk factor profile, have been examined and found to be helpful in reducing the rate of falls [37].

A number of strategies have been identified for preventing childhood injuries, including injuries from falls, although they may not necessarily have been tested in relation to falls specifically. Some of these strategies include: use of safety gates at the top and bottom of stairways; not allowing children under 6 years old to sleep in the top bunks of bunk beds; use of seat belts in the seats of shopping carts; use of appropriate helmets for activities such as bicycle riding, skateboarding, and horseback riding; and age and activity-appropriate supervision by adult caregivers [38]. Finally, a number of countries have developed playground safety standards in order to reduce the risk of playground injuries. Research suggests that lowering the height of play structures and using softer surfaces at ground level can reduce the risk of playground injuries [39].

ASSAULT-RELATED TBI

Definition/Mechanism

Assault-related TBIs are injuries intentionally inflicted by other people. Assault-related TBI can result from firearms, sharp objects, blunt objects, pushing, or punching. A special type of assault-related TBI is pediatric abusive head trauma, which is caused by violent shaking, impact to the head, or both [40].

Epidemiology

Deaths from assault-related TBI are highest among children 0 to 4 years old (43% of TBI-related deaths in this age group) [1]. In comparison, assault-related TBI deaths are between 15% and 20% of TBI-related deaths among those ages 5 to 44 years old, and only 8% and 2% among those ages 45 to 64 years old and those 65 and over, respectively. Among children less than 2 years old, the population rate of fatal TBI that does not meet the definition for pediatric abusive head trauma is 3.6 times higher than the rate of fatal pediatric abusive head trauma [41]. The rate of fatal pediatric abusive head trauma ranges from 2.1 per 100,000 for infants to 0.2 for children 4 years old, with peak rates among 30- to 89-day-old infants [41]. Fatal assault-related TBI among young children is higher among males compared to females, and among non-Latino Black and American Indian/Alaska Native compared to White [41].

Assault-related TBI hospitalizations account for 10% or less of all TBI-related hospitalizations [1]. The incidence of hospitalizations attributed to assault-related TBI among children up to 36 months of age is 58 per 100,000 children with the highest incidence among infants [42]. The annual incidence of hospitalizations attributed to pediatric abusive head trauma is lowest in the Northeast and highest in the Midwest [43].

Assault is a relatively common cause (30% and 22%, respectively) of TBI-related ED visits among those ages 15 to 24 years old and 25 to 44 years old [1].

Etiology

There are multiple individual, family, neighborhood, and societal-level risk factors for perpetrating assault or violence. It is the cumulative and interactive impact of risk factors that lead to perpetration of violence. Perpetrators of violence, regardless of the relationship (e.g., caregiver, partner, friend, or acquaintance) or lack of relationship (i.e., stranger) to their victims have several risk factors in common. At the individual level, perpetrators often show certain neurocognitive deficits, such as hostile attributional biases and poor impulse control [44–46]. A large and growing body of research links these deficits to exposure to chronic stressors prenatally or in early childhood affecting the volume, connectivity, and chemistry of the brain, especially in the prefrontal cortex, the hippocampus, and the amygdala [47]. Family-level stressors that may contribute to violence perpetration include experiencing child maltreatment or witnessing partner violence as a child [47]. Chronic stressors may also result from living conditions that affect children directly (e.g., poverty); [48] or through their effects on parenting behaviors [49] or parental relationships [50]. At the community level, stressors shared by different types of perpetrators include living in concentrated disadvantage [51–53] and exposure to community violence [51–52, 54], while income inequality [55–57] and country-level poverty [56–58] are societal-level stressors commonly shared.

Prevention Strategies

The widely implemented strategy of educating new parents about infant crying and the dangers of shaking has shown a positive impact on pediatric abusive head trauma in some settings [59–60]; but not in others [61–62]. However, there are several evidence-based approaches to preventing overall child maltreatment (i.e., primary prevention) such as screening parents of young children for risk factors of child maltreatment [63] or for needed services [64], home visitation [65], child–parent centers [66], and strengthening household economics [67]. Home visitation and strengthening household economics have also shown promise in preventing youth violence perpetration [68–71] and preventing involvement in partner violence [72]. Child–parent centers can also have preventive effects on youth violence [69].

Focusing on preventing violence and early adversity in childhood is key to disrupting the intergenerational transmission of violence and setting children on a positive trajectory. However, even when children have been exposed to early adversity, preschool and school-based interventions can help children develop socio-emotional and problem-solving skills to avoid interpersonal violence [73]. Some of these programs also prevent partner violence [74].

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