Injury is the leading cause of death in children and young adults in the United States, regardless of gender, race, or economic status (2). In 1999, more than 1,500 children under the age of 14 years died from unintentional injuries, accounting for more deaths in this age group than all childhood diseases combined. In that same year, more than 13,500 adolescents and young adults in the 15- to 24-year-old age group died from unintentional injuries (2). For every injury death, an estimated 18 children require hospital admission, and 233 more visit an ED as a result of injuries (3).

Although the childhood injury death rate has been declining since the mid-1980s (Fig. 21-1), injuries continue to be a major public health problem and a great financial burden to society. The federal government pays approximately $12.6 billion each year in injury-related medical costs (i.e., ambulance, EMS, physicians, hospital, rehabilitation, and related treatment costs) and about $18.4 billion in death and disability payments (2). Even greater than these direct costs are the indirect costs of injury-related morbidity and mortality, described as “work loss cost” or “loss of productive years.” Work loss cost is the sum of the lifetime loss due to permanent disability, plus the cost due to temporary disability (4). This includes the victim’s lost wages and the value of lost household work, as well as the work loss of family and friends who care for the injured victim. The total financial cost of injuries in the United States is estimated to be more than $224 billion each year (2).

As researchers and health care providers have gained a better understanding of the magnitude of the problem of childhood injury, they have begun to stress the important difference between “injuries” and “accidents.” In the past, physicians commonly referred to injuries as “accidents” (i.e., a 2-month-old infant involved in a motor vehicle accident). Accidents are rare events that occur at random; these events are largely unforeseen, unpredictable, and unavoidable. An injury, in contrast, is “damage or harm to the body resulting in impairment or destruction of health” (5). Injuries are not random; they are predictable events that can be studied and analyzed. Specific factors can be identified that may increase the likelihood of injury (risk factors) or decrease the likelihood of injury (protective factors). Once these factors are identified, effective strategies can be developed to help avoid or prevent injuries.

The Haddon Matrix provides a conceptual model that can be used to analyze an injury event. Dr. William Haddon, a pediatrician who was appointed the first Director of the National Highway Safety Bureau in 1966, (6) identified three components of an injury event: the host, the agent, and the environment. The host is the person who is injured. The agent is the form of energy delivered to the host, such as kinetic, thermal, chemical, or electrical. The environment is the setting where the agent meets the host, and refers to both the physical and sociocultural setting. Environmental factors can cause the event or influence the event, such as an unfenced swimming pool or a toxin stored in an unmarked bottle or container.

In the Haddon Matrix, the three components of an injury event are considered at three different temporal phases: the preevent period, the event itself, and the postperiod event (7).

Opportunities to prevent morbidity and mortality due to an injury could be present before, during, and following the event. Table 21-1 illustrates the Haddon Matrix using pedestrian injuries as an example (6).

Nearly one-half of the children ages 1 to 4 years who are killed in motor vehicle crashes each year are not restrained while riding in the car (8), despite the fact that all 50 states currently have laws mandating the use of child safety seats. Proper safety restraints are estimated to reduce the risk of death by approximately 70% in infants and 55% in toddlers (8) (Table 21-3). Recent studies suggest that use of safety restraints is as high as 85% in infants and 60% in young toddlers, (9) but many times restraints are used incorrectly (10). Information provided through the National SAFEKIDs Campaign and the National Highway Traffic Safety Administration suggests a misuse rate as high as 80% to 90% (11,12).