WISCONSIN MEDICAL JOURNAL
The Epidemiology of Traumatic Brain
Injury in Wisconsin, 2001
Kelly S.Tieves, DO; Hongyan Yang, MS; Peter M. Layde, MD
ABSTRACT
Problem: Traumatic brain injury (TBI) is a leading
cause of death and disability in the United States. To
implement more effective injury prevention and treatment programs, it is important to identify the regional
impact, causes, risk factors, and trends of TBI. This
report summarizes the public health impact of TBI in
Wisconsin.
Methods: Data on fatal and non-fatal TBI injuries in
Wisconsin in 2001 were obtained from 2 separate data
sources: National Center for Vital Statistics and the
Wisconsin Bureau for Health Information. Rates of
fatal and nonfatal TBI were calculated using 2000 population estimates as denominators.
Results: There were 1059 TBI fatalities and 4006 living
TBI-related hospital discharges in Wisconsin in 2001.
The overall rate of TBI in Wisconsin for 2001 was 94.4
per 100,000 people. The number of fatal and nonfatal
TBI related injuries was higher for males than females,
at all ages, except nonfatal injuries in persons older than
65 years. Fatalities from TBI were highest in young
adults and the elderly.
Conclusions: TBI is a major cause of death and hospitalizations in Wisconsin. Male teens and young adults,
and the elderly are high-risk groups for TBI. Preventive
measures should be aimed at these high-risk groups.
INTRODUCTION
One-third of all injury-related deaths are the result of
traumatic brain injury, and an estimated 1.5 million US
residents suffer traumatic brain injury (TBI) each year, resultingg in over 50,000 deaths.1 TBI survivors often suffer
All authors are with the Medical College of Wisconsin. Doctor
Tieves is an assistant professor of Pediatrics, Critical Care, and affiliate faculty at the Injury Research Center. Mr Yang is a biostatistician in Family and Community Medicine. Doctor Layde is professor
of Family and Community Medicine and co-director of the Injury
Research Center.
22
permanent disability. In the United States, an estimated
5.3 million Americans live with TBI-related disability.2
Age-adjusted TBI-related hospitalization rates for
Wisconsin in 1999 were 67.4 per 100,000 people. The
risk of TBI was highest among infants, adolescents,
young adults, and people age 75 years and older.2
Overall fatalities in Wisconsin due to TBI were estimated to be 19.6 per 100,000 people.2 TBI is a leading
cause of trauma-related costs to the health care system.3
Estimated lifetime costs of TBI in the United States in
1995 were $56.3 billion.4
To implement more effective injury prevention and
treatment programs, it is important to identify the
causes, risk factors, and trends of TBI. The aim of this
report is to provide current information on the scope
and impact of TBI in Wisconsin.
METHODS
For this report, 2 data sources were used. Fatal injury
data were obtained from the National Vital Statistics,
multiples cause of death public use files for 2001.5
Nonfatal injury data were obtained from Wisconsin
Bureau of Health Information for hospital discharges
in 2001.
TBI Definitions
TBI fatalities were defined according to the case definition in the Central Nervous System Injury Surveillance
Data Submission Standards6 as all deaths where injury
was assigned as the underlying cause of death and which
had any one of the following (ICD-10) codes present in
any of the diagnosis fields (International Classification
of Diseases, Tenth Revision7):
• S01.0-S01.9 (open wound of the head)
• S02.0, S02.1, S02.3, S02.7-S02.9 (fracture of the skull
and facial bones)
• S04.0 (injury to optic nerve and pathways)
• S06.0-S06.9 (intracranial injury)
• S07.0, S07.1, S07.8, S07.9 (crushing injury of head)
• S09.7-S09.9 (other and unspecified injuries of head)
Wisconsin Medical Journal 2005 • Volume 104, No. 2
WISCONSIN MEDICAL JOURNAL
Table 1. Number, Rate* and Case Fatality Rate† of Traumatic Brain Injury-Related Deaths and Hospital Discharges By Age and
Sex, Wisconsin 2001
Age
Total TBI
Cases (N)
Rate per
100,000*
Non-fatal TBI
Discharges (N)
Rate per
100,000*
TBI Deaths
(N)
TBI Death Rate Case Fatality
per 100,000*
Rate† (%)
Male
0-4
5-15
16-19
20-24
25-34
35-44
45-64
65+
Subtotal
147
286
307
369
405
461
651
714
3340
84.0
71.3
147.0
202.3
113.0
105.0
110.0
244.9
126.1
134
252
234
277
308
349
475
511
2540
0-4
5-15
16-19
20-24
25-34
35-44
45-64
65+
Subtotal
97
147
106
89
114
187
257
728
1729
58.0
38.5
53.4
50.9
32.8
42.8
43.0
177.1
63.7
89
135
91
62
90
156
224
619
1466
Total
5065
94.4
4006
76.6
62.8
112.1
151.9
85.9
79.5
80.1
175.3
95.9
13
34
73
92
97
112
176
203
800
7.4
8.5
35.0
50.4
27.1
25.5
29.7
69.6
30.2
8.8
11.9
23.8
24.9
23.9
24.3
27.0
28.4
24.0
53.2
35.4
45.9
35.4
25.9
35.7
37.5
150.6
54
8
12
15
27
24
31
33
109
259
4.8
3.1
7.6
15.4
6.9
7.1
5.5
26.6
9.5
8.2
8.2
14.2
30.3
21.1
16.6
12.8
15.0
15.0
74.7
1059
19.7
21.0
Female
*Age adjusted rates per 100,000 people based on US Census 2000.
†Case fatality rate=(fatal injury/[fatal + nonfatal injury]) x 100.
•
•
•
•
T01.0 (open wounds involving head with neck)
T02.0 (fractures involving head with neck)
T04.0 (crushing injuries involving head with neck)
T06.0 (injuries of brain and cranial nerve with injuries of nerves and spinal cord at neck level)
• T90.1, T90.2, T90.4, T90.5, T90.5, and T90.9 (sequelae of injuries of head)
Non-fatal TBI cases were identified from hospital
discharge data and were included if the patient was alive
at discharge and had one of the following codes, based
on the International Classification of Diseases, Ninth
Revision, Clinical Modification (ICD-9-CM),8 in any
of the diagnosis fields:
• 800.0-801.9 (fracture of the vault or base of the skull)
• 803.0-804.9 (other and unqualified multiple fractures
of the skull)
• 850.0-854.1 (intracranial injury, including concussion, contusion, laceration, and hemorrhage)
• 950.1-950.3 (injury to the optic chiasm, optic pathways, and visual cortex)
• 959.01 (head injury, unspecified)
• 995.55 (shaken infant syndrome)
All newborns born in the hospital were excluded
from analysis.
ANALYSIS
The mechanism of fatal injury was classified by external
cause of injury in to major cause-of-injury groupings
using ICD-10 codes.9 The mechanism of nonfatal injury
was classified by external cause of injury (E codes) according to standards in the CDC guidelines.10
The rates of fatal and nonfatal TBI were calculated
using 2000 population estimates from the US Bureau of
Census11 as denominators. Age-, mechanism-, and gender-specific rates were calculated for fatal and nonfatal
TBI using 2000 population figures. Case fatality rates
were calculated using the following formula: Case fatality
rate=(fatal injury/[fatal + nonfatal injury]) x 100. SAS version 8.0 software (Cary, NC) was used for all analyses.
RESULTS
There were 1059 TBI fatalities and 4006 living TBI-related hospital discharges in Wisconsin in 2001. The
overall rate of TBI in Wisconsin for 2001 was 94.4 per
100,000 people. The TBI-related hospital discharge rate
was 74.7, an increase of 10.8% from 67.4 in 1999, and
slightly higher than the national age-adjusted hospital
discharge rate for TBI of 69.7.12 The rate of fatalities due
to TBI—19.7—showed no corresponding increase from
Wisconsin Medical Journal 2005 • Volume 104, No. 2
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WISCONSIN MEDICAL JOURNAL
Non Fatal
Fatal
Age
Figure 1. Number of non-fatal and fatal traumatic brain injury
by age and gender, 2001.
the 1999 estimate of 19.6,2 and is similar to the national
rate of 19.8. (Table 1).
The number of fatal and nonfatal TBI-related injuries
was higher for males than females, at all ages, except nonfatal injuries in persons older than age 65 (Figure 1). The
hospital discharge rate for males was almost 2 times than for
females, and fatality rates from TBI occurred 3 times more
frequently in males than females (Table 1). Case fatality rates
were similar between males and females. Males aged 16-24
had the highest rates of TBI fatalities and hospital discharges
(Table 1). Hospital discharge rates were highest for adolescents, young adults, and the elderly. Fatalities from TBI
were highest in young adults and elderly.
The racial distribution of TBI fatalities was similar
to the demographic composition of Wisconsin. Whites
accounted for just over 90% of all TBI fatalities, while
blacks accounted for approximately 7%. Information
about race was not available for hospital discharges.
Most TBI fatalities were the result of unintentional
injuries (64%), but nearly one-quarter were due to suicide (22.7%), and just over 10% were the result of homicide. Motor vehicle crashes, firearms, and falls were
the leading causes of death from TBI. Falls and motor
vehicle-related incidents were the leading causes of nonfatal TBI-related hospital discharges (Tables 2).
The rate of in-hospital death for TBI injuries was 6.2
per 100,000 people, which represents 7.7% of TBI ad-
24
missions. The majority of those hospitalized for TBIrelated injuries were discharged to home and about onequarter of TBI admissions were discharged to another
care facility (Table 3).
DISCUSSION
The major findings of this report demonstrate the large
number of persons surviving TBIs, many of whom live
with TBI-related disabilities.2 Male teens and young
adults, and the elderly are high-risk groups for TBI.
These findings emphasize the importance of TBI as a
major public health and clinical problem, not only because of the deaths associated with TBI, but also because of the large number of persons who survive the
injury but require extensive treatment and rehabilitation. Better information on the outcomes of nonfatal
TBI, including the impact on quality of life, is needed
to quantify the individual and societal impact.
Male teens and young adults, and the elderly are highrisk groups. It has been reported previously about the
risk-taking behaviors associated with young adult males.13
Targeting this population for behavioral counseling regarding risk-taking behaviors and use of personal protective equipment may have an impact on future injury.14
The principal mechanism of fatal TBI or hospitalization for the elderly is falls. Many result in prolonged
hospitalization and rehabilitation needs in intermediate
care facilities. Some community interventions have been
implemented to prevent the large number of falls and
injuries in the elderly with some impact on the morbidity and mortality associated with falls.15,16
While data sources used for this report did not provide information about the use of personal protective
equipment for those injured as a result of motor vehicle-related and pedal cyclist incidents, we know from
previous reports that the use of seatbelts, car seats, and
bicycle helmets reduce injury risk, and the use of these
devices can be influenced through educational, behavioral, and legislative strategies.17,18
The information presented in this report has several
limitations. Those individuals treated and released from
an emergency department (ED) and those who did not
seek or have access to medical care were not captured by
this report. ED data is available from 2002; however, the
mortality data for 2002 had not been released for public
use at the time of this report. ED data would provide
information on less severe TBI, which could have more
subtle long-term neurological problems, such as learning disabilities and difficulties concentrating that could
impair school or work performance.
Secondly, administrative data sources were used to
Wisconsin Medical Journal 2005 • Volume 104, No. 2
WISCONSIN MEDICAL JOURNAL
Table 2. Number, Percentage, and Rate* of Nonfatal and Fatal Traumatic Brain Injury by Mechanism, Wisconsin 2001
Characteristic
Motor-Vehicle Occupant
Motorcyclist
Pedal Cyclist MVC
Pedestrian MVC
Falls
Assault
Suicide/Self-inflicted
Struck By/Against
Bicycle
Other/Unspecified/Unknown
Total
Nonfatal
(N)
946
192
34
118
1708
296
10
193
80
429
4006
Rate per
100,000*
Fatal
(N)
Rate per
100,000*
Case Fatality
Rate†
17.6
3.6
0.6
2.2
31.8
5.5
0.2
3.6
1.5
NA
74.7
283
46
3
29
218
113
240
7
1
119
1059
5.3
0.9
0.1
0.5
4.1
2.1
4.5
0.13
0.01
NA
19.7
23.0
19.3
8.1
19.7
11.3
27.6
96
3.5
1.2
NA
20.9
* Per 100,000 people based on US Census 2000.
†Case fatality rate=(fatal injury/[fatal + nonfatal injury]) x 100.
MVC = Motor Vehicle Crash; NA = Not Applicable
develop this report. Although this data is easily accessible and captures a large proportion of TBI-related
deaths and hospitalizations, its variability in abstracting
and coding of medical charts may lead to inconsistencies. The hospital discharge data is currently using the
ICD-9-CM coding system and the mortality data was
recorded using ICD-10. The ICD-10 external cause of
injury mortality codes are very different, with variability in detail, than codes in ICD-9. ICD-10 has alphanumeric categories rather than numeric categories and
some chapters have been rearranged, some titles have
changed, and conditions have been regrouped. The new
ICD-10 had almost twice as many conditions as the
ICD-9-CM system. When comparisons were done between the ICD-9 code set (800-801,804-804, 850-854,
873, 905.0, 907.0) and the ICD-10 code set the agreement between the 2 systems is nearly 96.5% with a
comparability ratio of 0.9985.6
This report may contain some duplicative reporting.
Individuals who die during a readmission for a prior traumatic brain injury would be counted in both the mortality data and the hospital discharge data. Because patient
identifiers are not available in these datasets, we were not
able to identify how often this may have happened.
CONCLUSION
Traumatic brain injury is a significant cause of death and
hospitalizations in Wisconsin. The incidence is highest
in male adolescents and young adults, and the elderly.
Adolescent and young adult males are at particularly
high risk of TBI. The elderly are at very high risk of
falls. Preventive measures focusing on these high-risk
groups and mechanisms of injury may make it possible
to impact the significant public health burden of TBI.
Table 3. Number, Percent and Rate for Disposition of
Hospitalized Traumatic Brain Injury Patients, Wisconsin 2001
Disposition
Routine Home
Transfer to Another Facility
Home Under Care
Hospice Home
Hospice-Medical Facility
Left Against Medical Advice
Expired
No.
%
Rate*
2823
1011
131
5
3
33
332
65.1
23.3
3.0
0.1
0.07
0.8
7.7
52.6
18.8
2.4
0.09
0.05
0.6
6.2
* Per 100,000 people based on US Census 2000
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WISCONSIN MEDICAL JOURNAL
THE EPIDEMIOLOGY OF TRAUMATIC
BRAIN INJURY IN WISCONSIN, 2001
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Wisconsin Medical Journal 2005 • Volume 104, No. 2
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