1.0  Tutorial:  How to get started

2.0  Overview:  An overview of Injury Maps' background and purpose

3.0  National Injury Maps and Data Methods:  An in-depth description of the national injury maps and the methods used to calculate the data.

4.0  State Injury Maps and Data Methods:  An in-depth description of the state injury maps and the methods used to calculate the data.

5.0  Definitions:  Definitions of key Injury Maps terms.

6.0  FAQs:  Frequently asked questions and answers.

2.0  Overview

In 1998, injury accounted for 146,941 deaths in the United States.  Unintentional injury, suicide, and homicide ranked among the top 15 leading causes of death in the U.S., with unintentional injury as the fifth leading cause of death.  Consequently, many people--from health professionals to students--are interested in injury prevention.  When designing and implementing injury prevention programs, state and national geographic patterns in injury death are important considerations.  Injury mortality maps display state or national geographic patterns in injury death.

Injury Maps is NCIPC's web-based mapping system that provides you with the geographic distribution of injury-related mortality in the United States. The system contains county-level maps of age-adjusted mortality rates in the contiguous United States and in each state. The system offers maps of mortality rates for nine major causes or types of injury-related deaths: 

• firearm 
• homicide 
• suicide 
• traumatic brain injury (TBI) 
• motor-vehicle (traffic-related)
• fall 
• fire and burn
• drowning
• unintentional poisoning.

For more background information, see the article about Injury Maps in the March 2003 edition of the newsletter Public Health GIS News and Information, available from the National Center for Health Statistics website.

The recommended bibliographic citation for Injury Maps is:

CDC. Injury Mortality Maps of the United States, 1989–1998. Atlanta, GA, 2001.

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3.0  National Injury Maps and Data Methods

Injury Maps' national maps show the geographic distribution of stabilized age-adjusted county mortality rates across the United States for the nine major causes or types of injury death. All maps and their corresponding figures express rates as the number of deaths per 100,000 population.

The methods NCIPC used to compute age-adjusted mortality rates for these maps are described in detail in Injury Mortality Atlas of the U.S..¹  NCIPC used a statistical procedure called empirical Bayes (EB) to stabilize the county age-specific rates. These EB rates were then used to calculate age-adjusted rates to the 2000 standard U.S. population.²  This methodology provided county-level mortality rates that you can compare across the United States.

Both the number of injury-related deaths and the population denominator data--except for traumatic brain injury (TBI)--were taken from the Compressed Mortality File (CMF)³ produced by the National Center for Health Statistics (NCHS).  Number of deaths and population estimates used to calculate mortality rates for TBI were obtained from the NCHS multiple-causes-of-death data tapes and the U.S. Bureau of Census, respectively. The case definition of a TBI death is described in detail in "Monitoring the Impact of Traumatic Brain Injury."⁴  For a summary of the types and causes of death included in Injury Maps and their associated International Classification of Diseases, Ninth Revision,⁵ nature of injury diagnosis codes (i.e., ICD-9 800-899 codes) or external cause of injury codes (i.e., ICD-9 E800-E999 codes), see Table 1.  E-code groupings are similar to those used in NCIPC's injury mortality atlas.¹

National Map Display
Beside each map is a chart showing the color scheme used for mapping counties with high mortality rates--i.e., rates at or above the 75th national percentile.  The color scheme shows counties with age-adjusted EB mortality rates below the 75th national percentile in white, counties with rates from the 75th percentile through the 89th percentile in blue, and counties with rates at or above the 90th percentile in red.  This chart also shows the number of counties represented in each percentile category.  Below this chart is a table that provides more statistics, specifically the percentile distribution of the age-adjusted EB mortality rates across counties.

Recommended Citation
The recommended bibliographic citation for Injury Maps is:

CDC. Injury Mortality Maps of the United States, 1989–1998. Atlanta, GA, 2001.

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Injury Maps offers state maps of injury mortality by cause. The methods NCIPC used to compute age-adjusted mortality rates for these maps are described in detail in Injury Mortality Atlas of the U.S..¹  NCIPC used a statistical procedure called empirical Bayes (EB) to stabilize the county age-specific rates. These EB rates were then used to calculate age-adjusted rates to the 2000 standard U.S. population.²  This methodology provided county-level mortality rates that you can compare across the United States. County boundaries are shown in the state maps to help identify specific counties.

Both the number of injury-related deaths and the population denominator data--except for traumatic brain injury (TBI)--were taken from the Compressed Mortality File (CMF)³ produced by the National Center for Health Statistics (NCHS).  Number of deaths and population estimates used to calculate mortality rates for TBI were obtained from the NCHS multiple-causes-of-death data tapes and the U.S. Bureau of Census, respectively. The case definition of a TBI death is described in detail in "Monitoring the Impact of Traumatic Brain Injury."⁴  For a summary of the types and causes of death included in Injury Maps and their associated International Classification of Diseases, Ninth Revision,⁵ nature of injury diagnosis codes (i.e., ICD-9 800-899 codes) or external cause of injury codes (i.e., ICD-9 E800-E999 codes), see Table 1.  E-code groupings are the same as those used in NCIPC's injury mortality atlas.¹ 

State Map Display
As with the national maps, you select the color scheme.  The default color scheme features counties with mortality rates in the 75th through 89th national percentiles as blue and counties with rates falling at or above the 90th national percentile as red.

Beside each map appears a table with the age-adjusted national and state rates and the average annual numbers of deaths from 1989 through 1998. The table also includes an estimate of the excess deaths per year for each cause of injury. NCIPC obtained these estimates by multiplying the excess death rate by the state’s average annual population. Excess death rates were calculated by subtracting the national rate from the rate within the state. Consequently, you can interpret a state’s excess deaths per year for a given type of injury as the number of additional deaths each year in the state because of the state’s mortality rate being higher than the national rate. 

The excess death estimates depend on state population size.  For example, if two states have the same excess death rate, the state with the larger population will have more excess deaths.  You can use excess deaths estimates to evaluate the relative importance of causes or types of injury death within a state. However, take caution when comparing excess deaths among states because different population sizes can produce significantly different numbers of excess deaths--even when states have identical death rates. Also, keep in mind that you cannot calculate a state’s total excess injury deaths by adding the nine estimates given on the state map page because:

1. homicides and suicides involving firearms are counted again in the firearm-related category, 
2. traumatic brain injury (TBI) deaths include all causes of injury death and 
3. some causes of injury death are not included in this system.

Recommended Citation
The recommended bibliographic citation for Injury Maps is:

CDC. Injury Mortality Maps of the United States, 1989–1998. Atlanta, GA, 2001.

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1. Devine OJ, Annest JL, Kirk ML, Holmgreen P, and Emrich SS. (1990). Injury Mortality Atlas of the United States, 1979––1987. Atlanta, GA: National Center for Injury Prevention and Control.

2. Hoyert DL, Anderson RN. (2001). Age-adjusted death rates: Trend data based on the year 2000 standard population. National vital statistics reports; 9(9). Hyattsville, Maryland: National Center for Health Statistics.

3. Centers for Disease Control and Prevention, National Center for Health Statistics (1998). Public use data tape documentation Compressed Mortality File, 1989––1998. Hyattsville, MD: U.S. Department of Health and Human Services.

4. Waxweiler RJ., Thurman D, Sniezek J, Sosin D, and O’’Neil J. (1995) Monitoring the impact of traumatic brain injury: A review and update. J. Neurotrauma 12, 509––516.

5. World Health Organization. Manual of the international statistical classification of diseases, injuries, and causes of death. 9^th revision. Geneva, Switzerland: World Health Organization, 1977.

 
Table 1. Types and Causes of Injury Death and Associated ICD-9 Codes^*