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Traumatic Brain Injury in the United States:
A Report to Congress


CDC Estimates of Traumatic Brain Injury-Related Disability

Prevalence

The CDC's National Center for Injury Prevention and Control estimates that 5.3 million U.S. citizens (2 percent of the population) are living with disability as a result of a traumatic brain injury. This represents the prevalence of TBI disability, defined as the proportion of persons in the population at a given time who have disability resulting from a traumatic brain injury. To estimate the prevalence of disability from TBI in the United States, CDC developed a model incorporating data on the incidence of TBI, severity of injury, and likelihood of disability given a specific level of injury severity.22 Data come from several sources:

  • CDC estimated the incidence of TBI by using its case definition and 1970-1995 National Hospital Discharge Survey (NHDS) data, obtained from CDC's National Center for Health Statistics.1
  • CDC estimated the severity of TBI by using NHDS data, classified according to ICD-9-CM-derived Abbreviated Injury Scale23 (ICD/AIS) scores by means of a computer algorithm (ICDMAP-90).24
  • Calculating the likelihood of disability following TBI at each level of severity required two data sources. For injuries occurring in 1980 or after, CDC obtained preliminary follow-up data from the Colorado TBI Registry and Follow-up System,26 which surveyed TBI survivors one year after injury and measured disability by using the Functional Independence Measure.27 For injuries that occurred before 1980, we used historical data reviewed by Kraus.17

The model uses these data to estimate the number of persons alive in 1996 who had ever had a TBI that required hospitalization and resulted in long-term disability. It incorporates differences in rates across age groups, variations in injury severity, and changing patterns in hospital admissions related to severity. The model does not account for disability among people who visited emergency departments or outpatient clinics with a TBI but were not admitted to the hospital. Because of this, our estimate of 5.3 million U.S. citizens living with TBI-related disability may be low. Other restrictions in existing data and methods may also affect the accuracy of this estimate.23 Given these limitations, some variation in future estimates of the prevalence of TBI-related disability is expected.

Incidence

According to NHDS data, the annual incidence rate of TBI hospitalizations has been declining since 1975, when it peaked at 234 per 100,000 population (500,000 cases). During 1990-1995, the mean annual incidence rate for persons hospitalized with TBI and survived was 99 per 100,000 population (260,000 cases). Hospitalization incidence patterns mirrored mortality rate patterns -- the highest rates were among persons 15-24 years of age and persons over age 65. Based on preliminary data from the Colorado TBI Registry and Follow-up System,25,26 we can estimate that each year, approximately 35 percent (80,500) of the 230,000 hospitalized survivors of TBI experience the onset of long-term disability. A small but unknown proportion of the more than 1 million persons with TBI who are not hospitalized may also experience long-term disability. If we assume this proportion is only 1 percent (existing data indicate it is probably greater), an additional 10,000 persons might have long-term disability. Thus, the estimated number of persons who become disabled each year from TBI is between 80,000 and 90,000.


 

Public Health Goals


The data in this report clearly demonstrate the importance of traumatic brain injury as a public health problem. Consequent to these injuries, each year more than 50,000 Americans die, nearly 230,000 are hospitalized and survive, and an estimated 80,000 to 90,000 experience the onset of long-term or lifelong disability. We have much work to do in these areas: primary prevention, acute care and rehabilitation, and improved data systems. This work requires that we better define groups with an increased risk of injury or adverse outcomes based on population characteristics, e.g., age, sex, and race or ethnicity.

Primary Prevention

Primary prevention of TBI is an important goal of public health efforts. Accomplishing this goal requires attention to each of the major external causes of these injuries: transportation, violence, and falls.

  • Transportation crashes are the leading cause of TBI-associated death among women and persons under 15 years of age. Fortunately, the rate of TBI-associated death due to transportation crashes has decreased approximately 40 percent since 1980. This drop is likely because of a combination of factors: an increase in seat belt and child safety seat use, an increase in the number of vehicles equipped with air bags, and a decrease in the incidence of driving while intoxicated. These positive changes should receive continued support. In addition, recent changes in speed limits and in seat belt and helmet use requirements should be evaluated to determine their impact on TBI incidence and death.
  • Violence is a leading cause of TBI--especially among males--and violence with firearms is the leading cause of TBI-associated death. Effective programs designed to decrease the occurrence of interpersonal and self-directed violence would help address this cause.
  • Falls are the third leading cause of TBI-associated death. Among women over 75 years of age and men over 85 years of age, falls are the leading cause of TBI-associated death. Falls are also a major cause of nonfatal TBI. Risk factors for falls among older persons may include the use of sedative, antidepressant, or other psychotropic medications; and impairments of balance or lower extremity function. Although better data are needed to define the circumstances of fall injuries among older persons, effective interventions may involve modifying the environment to reduce fall hazards and the impacts of falls and, where possible, reducing the use of medications with side effects that increase the risk of falling.

Acute Care and Rehabilitation

An effective public health response to TBI also requires concerted programs to minimize adverse outcomes among persons who do experience injury. We need research activities to improve the acute care and rehabilitation of persons with TBI, strategies to ensure they have access to appropriate care and services, and interventions to promote their independence and integration into the community for persons living with the effects of TBI.

Research to date indicates that the disabilities most often associated with TBI include cognitive, emotional, and--to a lesser extent--sensory and motor impairments. A traumatic brain injury may permanently alter a person's career or vocational aspirations and may also have profound effects on social and family relationships. In part, impairment of cognitive function may result in the loss of communication skills and memory, inability to organize tasks and solve problems, and decreased attention to detail. TBI may also cause emotional instability--especially impulsiveness--and changes in the ability to see, smell, and hear.

To help persons living with the effects of TBI, we need better information on the nature and scope of these disabilities, including who experiences TBIs, which rehabilitation treatment methods are most effective, and what services are useful and readily available.

In the near future, three important developments may increase our knowledge and promote the development of secondary and tertiary prevention programs.

  • The National Center on Medical Rehabilitation Research of the National Institutes of Health convened the "Consensus Development Conference on Rehabilitation of Persons with Traumatic Brain Injury" in October 1998. During the conference, experts addressed the epidemiology, consequences, mechanisms of recovery, therapies for cognitive and behavioral impairments, and rehabilitation models for TBI.
  • With CDC support, the Colorado Department of Public Health and Environment, Craig Hospital, and the South Carolina Department of Disabilities and Special Needs are developing population-based registries of persons with TBI. Designed as models for other States, these registries will better define the proportion of persons in entire States with various outcomes associated with TBI, the services to which persons with TBI have been referred, and the services that have actually been delivered.
  • Twenty-one States are promoting services for people with TBI via demonstration grants from the Health Resources and Services Administration, funded in 1997 under Public Law 104-166.

Improved Data Systems

Finally, more effective, targeted prevention requires better information on the occurrence of TBI and the circumstances surrounding those injuries (for example, the involvement of alcohol and other drugs or the use of personal protective equipment such as helmets). Expanded use of registries facilitates such data collection while also producing more precise information on the impact of these injuries. Standard measures for TBI outcomes need to be refined so that they will readily identify those adverse outcomes most amenable to prevention through rehabilitation and social support. A person's long-term outcome is related to the severity of the TBI. Better defining the relationship between the initial severity of an injury and a person's long-term outcome would help identify those persons who need ongoing medical care, rehabilitation, and other services. Such information also would also help health practitioners and policy makers ensure that these services are available in the community.


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This page last reviewed December 04, 2006.

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Centers for Disease Control and Prevention
National Center for Injury Prevention and Control