Incidence Rates of Hospitalization Related to Traumatic Brain Injury—12 States, 2002 FREE

MMWR. 2006;55:201-204

2 table omitted

Traumatic brain injury (TBI) is a major cause of death and disability in the United States. Each year, among the estimated 1.4 million persons who sustain a TBI, an estimated 80,000-90,000 experience the onset of long-term disability.^1- 2 Since the early 1990s, CDC has supported state-level, population-based surveillance of TBI associated with hospitalization or death. For 2002, 12 states* conducted TBI surveillance according to established CDC guidelines¹; the 2002 multistate data were finalized in December 2005 and are the most recent available. This report presents the results of TBI surveillance for 2002, which indicated that an estimated 74,517 persons (79.0 per 100,000 population) were hospitalized with TBI-related diagnoses in the 12 reporting states; unintentional falls, motor vehicle traffic (MVT) incidents, and assaults were the leading contributors to TBI-related hospitalizations. The findings underscore the need for states to continue to monitor TBI incidence and to implement effective injury-prevention programs.

Annual incidence rates of TBI-related hospitalization were analyzed by state, sex, age group, and intent/cause of injury. Race/ethnicity was not included in the analysis because approximately 17% of case records did not provide definitive racial/ethnic data. Cases of TBI-related hospitalization were defined on the basis of administrative hospital discharge records coded in accordance with the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM)† and from vital statistics data. During 2002, the 12 states initially reported 79,161 probable cases of TBI-related hospitalization. Medical records were reviewed by state program staff members for a random sample of 7,930 candidate cases in seven states, allowing estimation of the predictive value positive (PVP) (estimated at 0.95 overall) of the TBI surveillance case definition. Probable TBI case counts were adjusted downward on the basis of estimated PVP to eliminate false-positive bias.³ U.S. Census Bureau population estimates by state, age, and sex were combined with the PVP-adjusted surveillance data to calculate age-adjusted annual incidence rates per 100,000 population.

During 2002, a PVP-adjusted total of 74,517 persons were hospitalized with a TBI-related diagnosis in the 12 reporting states. The age-adjusted annual incidence rate of TBI-related hospitalization was 79.0 per 100,000 population; the rate was lowest in Nebraska (50.6) and highest in Arizona (96.9).

Persons aged ≥75 years had the highest TBI-related hospitalization rate (264.4 per 100,000 population), at least twice the rate for any other age group; persons aged 15-24 years had the next-highest rate (103.3). Persons aged ≥75 years also had the highest TBI-related hospitalization rate associated with unintentional falls (203.9 per 100,000 population), at least three times the rate for any other age group. The rates of TBI-related hospitalization associated with MVT incidents were highest among persons aged 15-24 years, 25-34 years, and ≥75 years; for each sex, the rate for persons aged 15-24 years was approximately twice the rate for any other age group.

Overall and in most states, the rate of TBI-related hospitalizations for males was approximately twice that for females. Among males, rates of TBI-related hospitalization associated with assault were highest in persons aged 15-24 years, 25-34 years, and 35-64 years; rates for males in each of these age groups were at least six times as high as those for females. Among females, rates of TBI-related hospitalization associated with assault were highest among those aged 0-4 years; females in this age group had approximately twice the rate as females in any other age group.

For all injury categories combined, 66% of patients were discharged without subsequent health-care assistance, 17% were discharged home with health services (e.g., outpatient rehabilitation) or to residential and rehabilitation facilities, 3% percent were discharged to an acute care hospital, and 1% left against medical advice. Approximately 6% of patients had no definitive coded discharge disposition, and 6% of patients died while hospitalized. The percentage of patients discharged without health-care assistance decreased with age, from 91% for persons aged 0-4 years to 32% for those aged ≥75 years. In contrast, the percentage of patients discharged to a residential facility increased with age, from 1% for persons aged 0-4 years to 31% for those aged ≥75 years, as did the percentage of those who died in the hospital (from 3% for persons aged 0-4 years to 13% for those aged ≥75 years).

VG Coronado, MD, RL Johnson, MSPH, M Faul, PhD, Div of Injury Response; SR Kegler, PhD, Office of Statistics and Programming, National Center for Injury Prevention and Control, CDC.

The data in this report indicate that TBI continues to be a substantial public health problem, resulting in 74,517 hospitalizations in the 12 reporting states during 2002. Findings indicate that, during 2002, rates of TBI-related hospitalization varied substantially by state but were higher among males regardless of state, age group, or intent/cause of injury. Most TBI-related hospitalizations were associated with unintentional falls, MVT incidents, and assaults.

The overall age-adjusted TBI-related hospitalization rate determined by this study was lower than the annual estimates for 1994-1995 from the National Hospital Discharge Survey (NHDS) (approximately 79 versus 98 per 100,000 population).⁴ Both studies included in-hospital deaths. Several factors might account for the difference in estimated rates: data from the CDC TBI surveillance system used in this study might not be representative of the entire United States⁵; states participating in the surveillance system do not report cases of TBI-related hospitalization that occur among nonresidents¹; as a hospitalization survey, NHDS can include multiple hospitalizations for the same injury, whereas the CDC data usually do not‡; and hospital admission practices for TBI might have changed over time. The TBI-related hospitalization rates described in this report are consistent with those of a previous CDC study based on TBI surveillance data for 1997.⁵ However, more specific comparisons cannot be made between the 2002 and 1997 studies because 1997 surveillance data excluded in-hospital deaths from the analysis and the estimated rates were not PVP adjusted.

The substantial variability in TBI-related hospitalization rates by state might be related to hospital admission practices, administrative ICD-coding practices, or actual differences in TBI risk factors and incidence among states.⁵ The differences in rates of TBI-related hospitalization resulting from falls and MVT incidents between persons aged 65-74 years and those aged ≥75 years suggest a need to analyze incidence data using narrower age ranges for older adults. The frequently used age grouping of ≥65 years might obscure changes in risk factors with increasing age.^5- 6

The findings in this report are subject to at least two limitations. First, findings are based on billing data that were not designed for public health surveillance purposes. Second, this study excluded persons treated in emergency departments or outpatient facilities and persons who sought no medical care.

Despite an apparent decline in the TBI-related hospitalization rate from 1994-1995 NHDS estimates, the results in this study for 2002 indicate that TBI continues to impose substantial demands on the U.S. health-care system. The findings suggest the need for ongoing and consistently defined TBI surveillance to support monitoring of general trends and to guide further development of prevention and intervention programs addressing the major age-specific causes of TBI.^7- 10

The findings in this report are based, in part, on contributions by JJ Seggerson, Div of Injury Response, National Center for Injury Prevention and Control, CDC.

*Alaska, Arizona, California, Colorado, Maryland, Minnesota, Nebraska, New Jersey, New York, Oklahoma, South Carolina, and Utah.

†ICD-9 and/or ICD-10 codes were used to identify cases. Cases identified with multiple qualifying codes were counted as single cases. TBI-related hospitalizations were identified using the following ICD-9-CM codes: 800.0801.9, 803.0804.9, 850.0854.1, 950.1950.3, 959.01, and 995.55. TBI-related hospitalizations that resulted in death and listed only a mortality code were identified using the following ICD-10 codes: S01.0S01.9, S02.0, S02.1, S02.3, S02.7S02.9, S04.0, S06.0S06.9, S07.0, S07.1, S07.8, S07.9, S09.7S09.9, T01.0, T02.0, T04.0, T06.0, T90.1, T90.2, T90.4, T90.5, T90.8, and T90.9. Although included in the case definition, T01.0, T02.0, T04.0, and T06.0 are considered invalid codes for use in the United States; however, only three cases were identified based exclusively on these four codes.

‡Data from the CDC TBI surveillance system are unduplicated by participating states and rechecked for probable duplicates at CDC.