Traumatic Brain Injury Among American Indians/Alaska Natives --- United States, 1992--1996

Traumatic Brain Injury (TBI) is a major cause of morbidity and mortality in the United States, resulting in approximately 52,000 deaths, 230,000 hospitalizations, and 80,000 disabilities annually (1). Among American Indians/Alaska Natives (AI/ANs), injuries are the second leading cause of death (2); however, few published reports concern nonfatal injuries in this population, especially for injuries such as TBI. To describe the causes and impact of TBI among AI/ANs, CDC analyzed Indian Health Service (IHS) hospital discharge data. This report summarizes the results of this analysis, which indicate that prevention strategies should focus on the leading causes of TBI hospitalizations, including motor-vehicle crashes, assaults, and falls.

IHS hospitalization data during 1992--1996 were analyzed. These data contain all hospital discharge records of AI/ANs who received services at an IHS, tribal, or contract hospital. Data were coded according to the International Classification of Diseases, Ninth Revision (ICD-9-CM) (3). TBI cases were selected if at least one of the diagnosis codes listed in CDC's Guidelines for Surveillance of Central Nervous System Injury (4) appeared in the diagnostic fields. These included the nature-of-injury diagnosis codes 800.0--801.9, 803.0--804.9, and 850.0--854.1. All TBI cases were E-coded (E800--E999) for the underlying external cause of injury. The underlying causes of TBI-related injuries were categorized as motor-vehicle collisions (E810--E825), falls (E880--E886 and E888), assaults (E960--E969), other (all other E-codes), or unspecified (E928.9 and E988.9). Hospital discharges in this report were limited to single-incident visits. Readmissions (ascertained for each year by matching sex, date of service, state, county, date of birth, and residence codes) were excluded to eliminate duplicate cases. Readmission in a subsequent year was treated as a separate injury event. Data from the California and Portland IHS regions were excluded because these regions do not have IHS or tribal hospitals. Incidence rates were calculated per 100,000 AI/AN residents eligible for services by using AI/AN resident population estimates from the IHS Demographic Statistics Team for each year (IHS, unpublished data, 1992--1996). Rates were age-adjusted to the 2000 U.S. standard population by the direct method. The latest year for which IHS hospital discharge data were available was 1996.

During 1992--1996, IHS, tribal, or contract-care hospitals recorded 4,491 TBI-related hospitalizations among AI/ANs, resulting in 21,107 hospital days (average length of stay: 4.7 days, range: 1--292 days). The average TBI-related hospitalization rate was 81.7 per 100,000 population (95% confidence interval=79.1--84.4) (Table 1). Of these 4,491 cases, 221 (5%) were fatal. Male TBI rates were 2.5 times greater than female rates. The AI/AN TBI rate was similar to the combined incidence rate of TBI hospitalizations reported by Colorado, Missouri, Oklahoma, and Utah (81.7 versus 84.8 per 100,000 population) (5), but lower than national TBI estimates (98.0) (6). The annual AI/AN TBI rate declined by 14% during 1992--1996. The major external causes of AI/AN TBI hospitalizations were motor-vehicle collisions (24%), assaults (17%), and falls (16%). Motor-vehicle--related hospitalization rates were highest among AI/ANs aged 15--24 years (34.2 per 100,000 population). For AI/ANs aged 25--34 years and those aged 35--44 years, assaults were the most common cause of TBI (28.2 and 23.6 per 100,000 population, respectively). Five of the assault cases involved firearms. For AI/ANs aged <14 years and those aged >45 years, falls were the leading cause of injury (17.7 and 19.4 per 100,000 population, respectively). AI/AN TBI-related hospitalization rates differed by geographic region with the highest rates occurring in the Northern Plains states and Alaska. Of the 1,418 records (32%) of TBI-related hospitalizations coded with "unspecified"* E-codes, 1,309 (92%) were from contract health-care providers.

Reported by: N Adekoya, DrPH, Div of Injury and Disability Outcomes and Programs, LJD Wallace, MSEH, Div of Unintentional Injury Prevention, National Center for Injury Prevention and Control, CDC.

Editorial Note:

TBIs among AI/ANs have serious consequences for patients, their families, and health-care delivery systems. These consequences partially are reflected by the number of hospital days for persons sustaining a TBI. Persons with TBI might experience substantial losses in quality of life, including physical, cognitive, and psychosocial impairments that require long-term rehabilitation therapy. Among AI/ANs, motor-vehicle crashes were involved in approximately one fourth of TBI-related hospitalizations. Because motor-vehicle--related injury is a major cause of TBI (5,6), increases in safety belt and child restraint use, enactment and enforcement of primary-occupant restraint laws, and policies focused on impaired driving are needed to reduce motor-vehicle--related TBI. During 1990--1994, 73% of motor-vehicle crashes resulting in AI/AN fatalities were alcohol-related (7). Fatally injured AI/AN drivers and passengers have some of the lowest safety belt use of any racial/ ethnic group in the nation (15.2% for drivers and 11.4% for passengers, respectively) (7). Enactment and enforcement of a law mandating safety belt use led to increases in safety belt use and a 29% reduction in motor-vehicle--related injury hospitalizations among Navajo Nation residents (8).

The proportion of TBIs attributed to nonfirearm assault among AI/ANs is approximately twice that shown in combined TBI data from Colorado, Missouri, Oklahoma, and Utah (17% versus 9%, respectively) (5). Falls contribute to TBI incidence among AI/ANs almost as much as assaults. Additional information about the circumstances and risk factors for these assault and fall injuries can assist agencies, tribes, and community practitioners in planning effective prevention strategies.

Several reasons might account for why the AI/AN TBI-related hospitalization rate is lower than the estimated national TBI-related hospitalization rate. First, the true number of TBI hospitalizations among AI/AN might be underreported because of the use of non-IHS or tribal treatment facilities by AI/AN residents. In Nevada, an estimated 73% of AI/AN injury hospitalizations were entered into the IHS data system (9). Second, injured AI/ANs covered under Medicare, Medicaid, or private health insurance might not be captured in the IHS data system (9). Third, access to advanced emergency medical care by AI/ANs residing in rural areas might be delayed when an injury occurs because greater travel distance might limit their chances of survival. Finally, risk-taking behaviors such as drinking and driving and not wearing safety belts (8) might indicate that AI/ANs are less likely to survive following a motor-vehicle crash, and thus will not be hospitalized and included in the IHS data system.

Although all IHS TBI-related hospitalization records are E-coded, the usefulness of these data is diminished because approximately one third of the records are coded "unspecified." Most (92%) "unspecified" E-codes reported for TBI cases occur among the IHS contract hospitals. Hospital discharge data that are E-coded have been used to evaluate injury trends, establish injury control priorities, and help in evaluating injury-prevention programs (8,10). Accurate and reliable external cause-of-injury information is needed to target and evaluate TBI injury-prevention programs among AI/ANs. Even a small reduction in TBI-related hospitalization will yield a major impact on the health of AI/ANs.

References

1. Thurman DJ, Alverson C, Dunn KA, Guerrero J, Sniezek JE. Traumatic brain injury in the United States: a public health perspective. J Head Trauma Rehabil 1999;14:602--15.
2. U.S. Department of Health and Human Services. Regional differences in Indian health, 1989--99. Rockville, Maryland: Indian Health Service, Office of Public Health, 2000.
3. World Health Organization. International classification of diseases: manual on the international statistical classification of diseases, injuries, and cause of death, ninth revision. Geneva, Switzerland: World Health Organization, 1977.
4. Thurman DJ, Sniezek JE, Johnson D, et al. Guidelines for surveillance of central nervous system injury. Atlanta, Georgia: CDC, 1995.
5. CDC. Traumatic Brain Injury---Colorado, Missouri, Oklahoma, and Utah, 1990--1993. MMWR 1997;46:8--11.
6. Thurman D, Guerrero J. Trends in hospitalization associated with traumatic brain injury. JAMA 1999;282:954--7.
7. Voas RB, Tippetts S. Ethnicity and alcohol-related fatalities: 1990 to 1994. Washington, DC: National Highway Traffic Safety Administration, U.S. Department of Transportation, 1999.
8. CDC. Safety-belt use and motor-vehicle--related injuries---Navajo Nation, 1988--1991. MMWR 1992;41:705--8.
9. Benefield R. Injury hospitalizations among American Indians in a Nevada service unit: supplementing IHS reported cases with the Nevada hospital discharge abstract. In: Berger LR, ed. Indian Health Service Injury Prevention Fellowship Program: a compendium of project papers, 1987--1998. Albuquerque, New Mexico: U.S. Department of Health and Human Services, Indian Health Service, 2000;157--60.
10. Quinlan KP, Wallace LJD, Furner SE, et al. Motor vehicle-related injuries among American Indian and Alaskan Native youth, 1981--1992: analysis of a national hospital discharge database. Injury Prev 1998;4:276--9.

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