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5.1 Source and Coding of National Data for Injury-Related Deaths
Comprehensive national data describing injury-related deaths were obtained from the National Center for Health Statistics (NCHS) National Vital Statistics System (NVSS) annual death data files. These files are derived from NCHS/NVSS multiple cause-of-death data.1 (For more information, contact NCHS at (301) 436-8500 or nchsquery@cdc.gov, or visit the NCHS/NVSS website.) WISQARS Cost of Injury Reports currently uses NCHS/NVSS death data representing calendar year 2010.
A death is considered injury-related when the data indicate an external cause as the underlying cause of death; WISQARS Cost of Injury Reports excludes deaths due to adverse effects of therapeutic drugs and adverse effects of medical and surgical care. For injury-related deaths, the WISQARS Cost of Injury reporting categories for injury intent, injury mechanism, affected body region, and nature of injury are based on codes in the International Classification of Disease, 10th Revision7 (ICD-10) external cause-of-injury and injury-related diagnosis code sets. External-cause-of-injury codes have been incorporated into the ICD-10 alphanumeric classification system as Chapter 20. ICD-10 external-cause-of-injury codes begin with the letters V, W, X, Y, or *U (terrorism) followed by a two-digit whole number (e.g., W25). Injury-related diagnosis codes have been incorporated into the ICD-10 alphanumeric classification system as Chapter 19. Injury-related diagnosis codes begin with the letters S or T followed by a two-digit whole number (e.g., S04). Some external-cause-of-injury or injury-related diagnosis codes also have a decimal point followed by another digit (e.g., V30.4, S04.5).
The reporting categories for intent and mechanism in WISQARS Cost of Injury Reports are consistent with the ICD-10 external-cause-of-injury mortality matrix which classifies injury-related deaths based on the external cause code identifying the underlying cause of death (one code per death record). The reporting categories for body region and nature of injury are consistent with the ICD-10 injury mortality diagnosis matrix pdf icon[pdf 38K] which classifies injury-related deaths according to the diagnosis codes (one or multiple codes per death record). NCHS collaborated with the National Center for Injury Prevention and Control and members of the Injury Control and Emergency Health Services section of the American Public Health Association to develop the standard groupings appearing in these classification matrices.
Notes: Stratification of data using the intent by mechanism classification scheme or the body region by nature of injury classification scheme, and/or stratification of data by sex and age may result in reports with small numbers of deaths for some strata. Cost-of-injury estimates that are based on 20 or fewer deaths are considered statistically unreliable (similar to the reliability/stability criterion employed in NCHS/NVSS reports).1 Even when based on more than 20 deaths, some cost-of-injury estimates can be statistically unreliable due to high variability of the case-level costs. For additional details on how cost estimates are evaluated in terms of statistical reliability, refer to Section 4.5.
The national data indicate that there were approximately 181,000 injury-related deaths among U.S. residents during calendar year 2010. All of these injuries are covered under the intent by mechanism classification scheme (described in Section 2.2). However, due to insufficient data on accompanying diagnoses, 235 of these injuries were excluded from the body region by nature of injury classification scheme (also described in Section 2.2).