ICD Injury Matrices

What are the matrices?

The ICD Injury matrices are frameworks designed to organize ICD coded injury data into meaningful groupings. The matrices were developed specifically to facilitate national and international comparability in the presentation of injury statistics.

Why are there so many matrices?

Injuries can be described in the ICD in two ways; either (1) as “external cause” which describes the cause and intent in a single code or (2) as the “nature of injury” which describes the body and nature of injury in a single code. There are multiple revisions of the ICD. There are also clinical modifications which are more detailed for use with morbidity data. There is also a mapping between the revisions of the ICD.

Which ICD revisions, clinical modifications, and injury codes have matrices available?

Revisions/modifications	External cause	Nature of injury
ICD–9	ICD–9 External cause	Not yet developed
ICD–9–CM	ICD–9–CM External cause	Barell Matrix
ICD–10	ICD–10 External cause	Injury Mortality Diagnosis Matrix
Map ICD–9 To ICD–10	ICD–9 modified to be consistent with ICD–10

What are External Cause of Injury (E–code) codes?

The external cause of injury describes the vector that transfers the energy to the body (e.g. fall, motor vehicle traffic accident, or poisoning) and the intent of the injury (e.g. whether the injury was inflicted purposefully).

External cause–of–injury codes (E–codes) are the ICD codes used to classify injury incidents by mechanism (e.g., motor vehicle, fall, struck by/against, firearm, or poisoning) and intent (e.g., unintentional, homicide/assault, suicide/self–harm, or undetermined) and. Sometimes the external cause is referred to as the "mechanism of injury" and the intent is referred to as the "manner of death".

In ICD–9, the external cause of injury codes are included in a Supplemental Classification and are designated with as "E800–E999.9". In ICD–10, external cause of injury codes are in Chapter 20 and begin with the letter V,X,W, and Y.

What are the injury diagnosis codes?

The injury diagnosis codes (or the nature of injury codes) are the ICD codes used to classify injury the body region (e.g. head, and the nature of injury (e.g. fracture, laceration). In ICD–9, the nature of injury codes are included in a Chapter XVII and are designated by codes 800–999. In ICD–10, nature of injury codes are in Chapter 19 and begin with the letter S or T.

The Barell matrix for ICD–9CM codes and the Injury Mortality Diagnosis Matrix for ICD–10 codes are two–dimensional arrays describing both the body region and nature of the injury.

What are External Cause of Injury (E–code) matrices?

The External Cause of Injury Matrix is a two–dimensional array designed to present both the mechanism and manner of the injury. External Cause of Injury matrices have been developed for ICD-9, ICD-9CM and ICD-10. The first E-code matrix was developed for the ICD–9 external cause codes. It was jointly developed by the Injury Control and Emergency Health Services section of the American Public Health Association and the International Collaborative Effort (ICE) on Injury Statistics.

Modifications to the ICD–9 external cause of injury matrix are available which make the matrix more compatible with the ICD–10 matrix. For more information see: How to map ICD–9 To ICD–10 for external causes .

The ICD–10 injury mortality framework for external cause–of–injury was developed to be as consistent as possible with the ICD–9 external cause–of–injury matrix. Representatives from NCHS, International Collaborative Effort on Injury Statistics, and Injury Control and Emergency Health Services section of the American Public Health Association participated in its development. In some cases, the ICD–10 external cause–of–injury mortality codes are different than the ICD–9 codes. When the codes vary, more often the codes allow more detail, but in some cases, less detail is provided. The ICD–10 matrix development was guided by logic and internal consistency rather than directly calculated ICD–9 to ICD–10 comparability ratios from dual coded data.

Several changes were made to the ICD–10 matrix that warrant attention:

• Two rows have been added. The first is labeled "All transport" and it includes all transport related deaths that were classified as unintentional: suicide, homicide, intent undetermined, and operations of war. In ICD–9, the codes for suicide and intent undetermined by crashing of a motor vehicle were included with motor vehicle traffic injuries. There is no indication in the actual codes that these are traffic deaths. The second row, "Other land transport" was added to accommodate new codes in ICD–10.
• A change was made to the transportation and drowning categories. The ICD–10 codes for water transportation–related drowning, V90 and V92, are included with the "other transport" codes rather than with the drowning codes. In the ICD–9 version of the matrix, the comparable codes, E830 and E832, were included with drowning. This change was made to be consistent with the categorization of other mechanisms of injury (i.e., falls, fires, and machinery) involved with water transport–related injuries.
• In the ICD–9 matrix, E846–E848 "Vehicle accidents not elsewhere classifiable" were categorized with other codes into the category "Other specified and classifiable". However, with the additional transportation categories in ICD–10, and to be consistent with the NCHS 113 Cause–of–Death list, ICD–10 codes V98–V99, "Other and unspecified transport accident", are included with other transportation codes (including water transport and air and space transport related accidents) in a group V90–V99, making them part of all transportation related accidents.

NOTE: The November 2002 version also includes the newly developed US ICD–10 codes for terrorism. The November 2002 version of the matrix shows a correction in the motor vehicle traffic category. Codes V81.1 and V82.1 were moved from the occupant codes to the other codes. In addition, codes X82 for suicide, Y03 homicide and Y32 intent undetermined for the crashing of a motor vehicle are included in the group, "Other land transport" and code Y36.1 is included with "Other transport." In the preliminary matrix, they were only included in the row for "All transportation."

How to map ICD–9 To ICD–10 for external causes

About every 10 to 20 years, the ICD is revised to stay abreast of advances in medical science and changes in medical terminology. ICD–10 was implemented in the US in 1999. The ICD–9 External Cause of Injury matrix was modified to be consistent with the ICD–10 matrix.

Classification and rule changes affect cause‑of‑death trend data by shifting deaths away from some cause–of–death categories and into others. ICD–10 and ICD–9 Comparability ratios are based on a comparability study in which the same deaths were coded by both the Ninth and Tenth Revisions. The comparability ratio was calculated by dividing the number of deaths classified by ICD–10 by the number of deaths classified by ICD–9. Comparability ratios measure the effect of changes in classification and coding rules and were calculated for all external causes of injury based on the external cause of injury mortality matrix. For information on all causes of death comparability ratios. See Comparability of Cause–of–death Between ICD Revisions

What is the Barell Matrix (ICD–9–CM)?

The Barell Injury Diagnosis matrix is a two–dimensional array of International Classification of Diseases, Ninth Revision, Clinical Modification (ICD–9–CM) diagnosis codes for injury (updated as of 2002) grouped by body region of the injury and the nature of the injury. The ICD–10 matrix is referred to as the Injury Mortality Matrix.

The Barell matrix provides a standard format for reporting injury data. This injury diagnosis matrix is a product of the International Collaborative Effort (ICE) on Injury Statistics. Guiding its development was the work of the late Vita Barell, of the Health Services Research Department in the Gertner Institute, Tel Hashomer, Israel and Ellen MacKenzie of the Johns Hopkins Center for Injury Research and Policy. The matrix is based on ICD–9–CM coded data and not on data directly obtained from patients. Future plans include a version of the matrix based on 3–digit ICD–9–CM codes that can be used for multiple cause of death analyses (when detailed 5–digit codes are often not available). In addition, once ICD–10–CM is adopted for use, the matrix will be 'translated' into those appropriate codes. A complete discussion of the matrix including guidelines for use and data analysis was published in the journal Injury Prevention (June 2002). The matrix was adopted for use by the State and Territorial Injury Prevention Directors Association and recommended as the basis for defining injury hospitalizations.

Excluded from the matrix are ICD–9–CM codes for adverse effects and complications of care. There is disagreement within the "Injury Community" as to whether these should be included. For the time being, they are excluded. This can certainly be reconsidered in future versions of the matrix.

• Changes to the Matrix for the May 2002 Update
• The Barell Body Region by Nature of Injury Diagnosis Matrix, 2001 [PPT - 600 KB]

What is the Injury Mortality Diagnosis (IMD) Matrix (ICD–10)?

The ICD–10 Injury Mortality Diagnosis (IMD) matrix is a framework designed to organize injury diagnosis mortality data into meaningful groupings by body region and nature of injury. The ICD–9–CM matrix is referred to as the Barell matrix. Injury diagnoses describe the body region and nature of the injury mentioned on the death certificate that are the injuries sustained as a result of the underlying external cause of injury death. The IMD matrix categorizes the nearly 1,200 injury diagnosis codes from ICD–10’s Chapter XIX (S and T codes, excluding adverse effects and complications of medical and surgical care [T79, T80–T88, T98.3]) by body region and nature of the injury. At its most detailed level, the ICD–10 matrix has 19 nature–of–injury categories and 43 body–region categories. For most analyses of mortality data, similar categories can be aggregated to reduce the categories to those most meaningful for mortality. The detailed structure can be readily collapsed into a more meaningful matrix for mortality using 16 nature–of–injury diagnosis categories and 17 body region of injury diagnosis categories. Categories for both axes were combined based on characteristics of the body region (e.g., foot and ankle injuries are part of “Other lower extremities”) as well as the number of injury diagnoses mentioned in a category (e.g. if there were too few). The latter was generally a reflection of the low lethality of the diagnosis (sprains and strains, for example). The body regions can be further combined into five groups; this is often useful for analyses using additional dimensions, such as external cause or age. The ICD–10 IMD Matrix is similar in structure to the Barell Injury Diagnosis Matrix that categorizes ICD–9–CM injury morbidity codes by body region and nature of injury. However, the ICD–10 matrix is adapted for use with mortality data, which tend to be less detailed than morbidity data, and also takes into account important changes related to the revision of the ICD classification scheme.

• Detailed ICD-10 Code Listing For All Injury Diagnosis Codes
  This Excel spreadsheet contains each of the ICD-10 injury diagnosis codes for the complete 20x43 IMD matrix.

Suggested citations for the matrices

External Cause–of–Injury (E–code) Matrices

ICD–10 suggested citation: NCHS. ICD–10: External cause of injury mortality matrix [online]. Available from: /nchs/injury/injury_matrices.htm

ICD–9 & ICD–9–CM suggested citation: CDC. Recommended framework for presenting injury mortality data. MMWR 46 (RR-14) Centers for Disease Control and Prevention. Available from: http://www.cdc.gov/mmwr/preview/mmwrhtml/00049162.htm. 1997.
ICD–9 modified to be consistent with ICD–10 External Cause of Injury

Injury Diagnosis Matrices

ICD–10 (IMD Matrix) suggested citation: L.A. Fingerhut and M. Warner, The ICD–10 Injury Mortality Diagnosis Matrix, Injury Prevention, 2006;12;24-29

ICD–9–CM (Barell Matrix) suggested citation: Barell V, Aharonson-Daniel L, Fingerhut LA, MacKenzie EJ, et al. An introduction to the Barell body region by nature of injury diagnosis matrix. Inj Prev 8:91–6. 2002.

Other references for the matrices

Bergen G , Chen LH, Warner M, Fingerhut LA. Injury in the United States: 2007 Chartbook. Hyattsville, MD: National Center for Health Statistics. 2008. [PDF - 6.7 MB]

Miniño AM, Anderson RN, Fingerhut LA, Boudreault MA, Warner M. Deaths: Injuries, 2002. National vital statistics reports; vol 54 no 10. Hyattsville, Maryland: National Center for Health Statistics. 2006. [PDF - 4.8 MB]

Anderson RN, Miniño AM, Fingerhut LA, Warner M, Heinen MA. Deaths: Injuries, 2001. National vital statistics reports; vol 52 no 21. Hyattsville, Maryland: National Center for Health Statistics.2004. [PDF - 4.5 MB]

ICD codes for matrices and SAS statements

For ICD codes for each of the matrices and the SAS statements, see Tools for Classifying ICD Codes.