Classifications

Diseases
Classification Name	Purpose	Notes
International Classification of Diseases, Ninth Revision (ICD-9)	The International Classification of Diseases (ICD) is designed to promote international comparability in the collection, processing, classification, and presentation of mortality and morbidity statistics.	The ICD-9 is no longer available in print. Volume I, modified for U.S. purposes, is available at: ftp://ftp.cdc.gov/pub/ Health_Statistics/NCHS/ Publications/ICD-9
International Classification of Diseases, Tenth Revision (ICD-10)	The International Classification of Diseases (ICD) is designed to promote international comparability in the collection, processing, classification, and presentation of mortality and morbidity statistics. The ICD-10 is used to code and classify mortality data from death certificates.	CDC web page: https://www.cdc.gov/ nchs/icd/icd10.htm . Links to an online version of ICD-10, at the World Health Organization’s:
International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM)	ICD-9-CM is the official system of assigning codes to diagnoses and procedures associated with hospital and ambulatory care utilization in the United States. It is based on ICD-9 and was developed by the National Center for Health Statistics (NCHS).	Links to CDC FTP files: https://www.cdc.gov/ nchs/icd/icd9cm.htm#ftp
International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM)	The National Center for Health Statistics (NCHS) is responsible for use of the International Statistical Classification of Diseases and Related Health Problems, 10th revision (ICD-10) in the United States. It has developed a clinical modification of the classification for morbidity purposes. The ICD-10 is copyrighted by the World Health Organization (WHO), which owns and publishes the classification. WHO has authorized the development of an adaptation of ICD-10 for use in the United States for U.S. government purposes.	CDC links to online versions: https://www.cdc.gov/ nchs/icd/icd10cm.htm
International Classification of Functioning, Disability and Health (ICF)	The ICF classification complements WHO’s International Classification of Diseases-10th Revision (ICD), which contains information on diagnosis and health condition, but not on functional status. The ICD and ICF constitute the core classifications in the WHO Family of International Classifications (WHO-FIC). The NACC has responsibilities to WHO in its “Terms of Reference” to promote the development and use of ICF in the light of practical experience.	A searchable version of the ICF is available at the WHO Web site at: http://www.who.int/icidh

Death and Injury
Classification Name	Purpose	Notes
Detailed listing of underlying causes of death used in the United States, the Each Cause List (ICD-10)	The most detailed listing of underlying causes of death used in the United States.	ftp://ftp.cdc.gov/ pub/Health_Statistics/NCHS/ Publications/ICD10/
Classification of Death and Injury Resulting from Terrorism	Developed by NCHS a set of new codes within the framework of the ICD and the ICD-9-CM that allow the identification of deaths from terrorism reported on death certificates through the National Vital Statistics System as well as for injuries and illnesses from terrorism reported on medical records used for statistical purposes and for reimbursement.	Classification for Mortality (Appendix I): https://www.cdc.gov/ nchs/icd/terrorism_code_appendix1.htm
		Changes in the Mortality Classification Index to Incorporate Terrorism (Appendix II) https://www.cdc.gov/ nchs/icd/ terrorism_code_appendix2.htm
		Ad Hoc Workgroup on the Classification of Death and Injury Resulting from Terrorism and Supporting Staff (Appendix III) at: https://www.cdc.gov/ nchs/icd/terrorism_code_appendix3.htm

Occupation
Classification Name	Purpose	Notes
Census Alphabetical Index of Occupations (2010)	The 2010 Census Alphabetical Index of Occupations was developed primarily for use in classifying a respondent’s occupation (employee’s type of work) as reported in the Census 2010, the Current Population Survey, the American Community Survey, and other demographic surveys conducted by the Census Bureau. The basic content of the Census 2010 Occupation Index is derived largely from previous editions and was developed to be consistent with the 2010 Standard Occupational Classification (SOC) manual.	http://www.census.gov/ hhes/www/ioindex/ ioindex.html
Census Alphabetical Index of Occupations (2002)	The 2002 Census Alphabetical Index of Occupations was derived primarily from the 2000 Census Alphabetical Index of Occupations. It was developed to address changes in occupations as they relate to the 2002 North American Industry Classification System (NAICS). The census 2002 occupational classification system was developed to be consistent with the 2000 Standard Occupational Classification (SOC) system.	http://www.census.gov/ hhes/www/ioindex/ ioindex.html
Census Alphabetical Index of Occupations (2000)	The 2000 Census Alphabetical Index of Occupations was developed primarily for use in classifying a respondent’s occupation (employee’s type of work) as reported in the Census 2000, the Current Population Survey, the American Community Survey, and other demographic surveys conducted by the Census Bureau. The basic content of the Census 2000 Index is derived largely from previous editions, however, many new titles were added to the occupation listing and some obsolete titles were deleted. The census 2000 occupational classification system was developed to be consistent with the 2000 Standard Occupational Classification (SOC) system.	http://www.census.gov/ hhes/www/ioindex /ioindex.html
Census Alphabetical Index of Occupations (1990)	The 1990 Census Alphabetical Index of Occupations was developed primarily for use in classifying a respondent’s occupation (employee’s type of work) as reported in the Census 1990, the Current Population Survey, and other demographic surveys conducted by the Census Bureau. The 1990 census occupational classification system was developed to be consistent with the 1980 Standard Occupational Classification (SOC) manual.	http://www.census.gov/ hhes/www/ioindex/ ioindex.html
Standard Occupational Classification (SOC 2010)	The 2010 Standard Occupational Classification (SOC) system is used by Federal statistical agencies to classify workers into occupational categories for the purpose of collecting, calculating, or disseminating data. All workers are classified into one of 840 detailed occupations according to their occupational definition. To facilitate classification, detailed occupations are combined to form 461 broad occupations, 97 minor groups, and 23 major groups. Detailed occupations in the SOC with similar job duties, and in some cases skills, education, and/or training, are grouped together. In comparison to the 2000 SOC, the 2010 SOC realized a net gain of 19 detailed occupations, 12 broad occupations, and 1 minor group.	http://www.bls.gov/SOC/
Standard Occupational Classification (SOC 2000)	The 2000 Standard Occupational Classification (SOC) System was developed in response to a growing need for a universal occupational classification system. It is used by federal agencies collecting occupational data, providing a means to compare occupational data across agencies. It is designed to cover all occupations in which work is performed for pay or profit, reflecting the current occupational structure in the United States.	http://www.bls.gov/ soc/2000/ socguide.htm

NNDSS
Classification Name	Purpose	Notes
Event code list for nationally notifiable diseases and other conditions of public health importance reported to CDC’s National Notifiable Diseases Surveillance System	Each disease or condition has an event code. For example, the event code for anthrax is 10350. Event codes are used by local, state, and federal surveillance information systems to help simplify storage and retrieval of information about cases of nationally notifiable or state reportable diseases or conditions.	The event code list includes a description of the verification procedures and publication criteria used by CDC’s National Notifiable Diseases Surveillance System for each disease or condition.
National public health surveillance case definitions used by the National Notifiable Diseases Surveillance System	Surveillance case definitions are used to define what a ‘case’ of disease is for public health surveillance purposes. They also help ensure diseases and conditions are classified and enumerated consistently across jurisdictions.	CDC staff and the Council of State and Territorial Epidemiologists (CSTE, www.cste.org ) collaborate to develop or revise national surveillance case definitions. Then, they are officially approved by CSTE. Surveillance case definitions include clinical, epidemiologic, and laboratory criteria to define what a ‘case’ of a specific disease or condition represents.

Page last reviewed: October 31, 2016
Page last updated: July 1, 2015
Content source:
- Division of Health Informatics and Surveillance

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Diseases
Classification Name	Purpose	Notes
International Classification of Diseases, Ninth Revision (ICD-9)	The International Classification of Diseases (ICD) is designed to promote international comparability in the collection, processing, classification, and presentation of mortality and morbidity statistics.	The ICD-9 is no longer available in print. Volume I, modified for U.S. purposes, is available at: ftp://ftp.cdc.gov/pub/ Health_Statistics/NCHS/ Publications/ICD-9
International Classification of Diseases, Tenth Revision (ICD-10)	The International Classification of Diseases (ICD) is designed to promote international comparability in the collection, processing, classification, and presentation of mortality and morbidity statistics. The ICD-10 is used to code and classify mortality data from death certificates.	CDC web page: https://www.cdc.gov/ nchs/icd/icd10.htm. Links to an online version of ICD-10, at the World Health Organization’s:
International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM)	ICD-9-CM is the official system of assigning codes to diagnoses and procedures associated with hospital and ambulatory care utilization in the United States. It is based on ICD-9 and was developed by the National Center for Health Statistics (NCHS).	Links to CDC FTP files: https://www.cdc.gov/ nchs/icd/icd9cm.htm#ftp
International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM)	The National Center for Health Statistics (NCHS) is responsible for use of the International Statistical Classification of Diseases and Related Health Problems, 10th revision (ICD-10) in the United States. It has developed a clinical modification of the classification for morbidity purposes. The ICD-10 is copyrighted by the World Health Organization (WHO), which owns and publishes the classification. WHO has authorized the development of an adaptation of ICD-10 for use in the United States for U.S. government purposes.	CDC links to online versions: https://www.cdc.gov/ nchs/icd/icd10cm.htm
International Classification of Functioning, Disability and Health (ICF)	The ICF classification complements WHO’s International Classification of Diseases-10th Revision (ICD), which contains information on diagnosis and health condition, but not on functional status. The ICD and ICF constitute the core classifications in the WHO Family of International Classifications (WHO-FIC). The NACC has responsibilities to WHO in its “Terms of Reference” to promote the development and use of ICF in the light of practical experience.	A searchable version of the ICF is available at the WHO Web site at: http://www.who.int/icidh

Death and Injury
Classification Name	Purpose	Notes
Detailed listing of underlying causes of death used in the United States, the Each Cause List (ICD-10)	The most detailed listing of underlying causes of death used in the United States.	ftp://ftp.cdc.gov/ pub/Health_Statistics/NCHS/ Publications/ICD10/
Classification of Death and Injury Resulting from Terrorism	Developed by NCHS a set of new codes within the framework of the ICD and the ICD-9-CM that allow the identification of deaths from terrorism reported on death certificates through the National Vital Statistics System as well as for injuries and illnesses from terrorism reported on medical records used for statistical purposes and for reimbursement.	Classification for Mortality (Appendix I): https://www.cdc.gov/ nchs/icd/terrorism_code_appendix1.htm
		Changes in the Mortality Classification Index to Incorporate Terrorism (Appendix II) https://www.cdc.gov/ nchs/icd/ terrorism_code_appendix2.htm
		Ad Hoc Workgroup on the Classification of Death and Injury Resulting from Terrorism and Supporting Staff (Appendix III) at: https://www.cdc.gov/ nchs/icd/terrorism_code_appendix3.htm

Occupation
Classification Name	Purpose	Notes
Census Alphabetical Index of Occupations (2010)	The 2010 Census Alphabetical Index of Occupations was developed primarily for use in classifying a respondent’s occupation (employee’s type of work) as reported in the Census 2010, the Current Population Survey, the American Community Survey, and other demographic surveys conducted by the Census Bureau. The basic content of the Census 2010 Occupation Index is derived largely from previous editions and was developed to be consistent with the 2010 Standard Occupational Classification (SOC) manual.	http://www.census.gov/ hhes/www/ioindex/ ioindex.html
Census Alphabetical Index of Occupations (2002)	The 2002 Census Alphabetical Index of Occupations was derived primarily from the 2000 Census Alphabetical Index of Occupations. It was developed to address changes in occupations as they relate to the 2002 North American Industry Classification System (NAICS). The census 2002 occupational classification system was developed to be consistent with the 2000 Standard Occupational Classification (SOC) system.	http://www.census.gov/ hhes/www/ioindex/ ioindex.html
Census Alphabetical Index of Occupations (2000)	The 2000 Census Alphabetical Index of Occupations was developed primarily for use in classifying a respondent’s occupation (employee’s type of work) as reported in the Census 2000, the Current Population Survey, the American Community Survey, and other demographic surveys conducted by the Census Bureau. The basic content of the Census 2000 Index is derived largely from previous editions, however, many new titles were added to the occupation listing and some obsolete titles were deleted. The census 2000 occupational classification system was developed to be consistent with the 2000 Standard Occupational Classification (SOC) system.	http://www.census.gov/ hhes/www/ioindex /ioindex.html
Census Alphabetical Index of Occupations (1990)	The 1990 Census Alphabetical Index of Occupations was developed primarily for use in classifying a respondent’s occupation (employee’s type of work) as reported in the Census 1990, the Current Population Survey, and other demographic surveys conducted by the Census Bureau. The 1990 census occupational classification system was developed to be consistent with the 1980 Standard Occupational Classification (SOC) manual.	http://www.census.gov/ hhes/www/ioindex/ ioindex.html
Standard Occupational Classification (SOC 2010)	The 2010 Standard Occupational Classification (SOC) system is used by Federal statistical agencies to classify workers into occupational categories for the purpose of collecting, calculating, or disseminating data. All workers are classified into one of 840 detailed occupations according to their occupational definition. To facilitate classification, detailed occupations are combined to form 461 broad occupations, 97 minor groups, and 23 major groups. Detailed occupations in the SOC with similar job duties, and in some cases skills, education, and/or training, are grouped together. In comparison to the 2000 SOC, the 2010 SOC realized a net gain of 19 detailed occupations, 12 broad occupations, and 1 minor group.	http://www.bls.gov/SOC/
Standard Occupational Classification (SOC 2000)	The 2000 Standard Occupational Classification (SOC) System was developed in response to a growing need for a universal occupational classification system. It is used by federal agencies collecting occupational data, providing a means to compare occupational data across agencies. It is designed to cover all occupations in which work is performed for pay or profit, reflecting the current occupational structure in the United States.	http://www.bls.gov/ soc/2000/ socguide.htm

NNDSS
Classification Name	Purpose	Notes
Event code list for nationally notifiable diseases and other conditions of public health importance reported to CDC’s National Notifiable Diseases Surveillance System	Each disease or condition has an event code. For example, the event code for anthrax is 10350. Event codes are used by local, state, and federal surveillance information systems to help simplify storage and retrieval of information about cases of nationally notifiable or state reportable diseases or conditions.	The event code list includes a description of the verification procedures and publication criteria used by CDC’s National Notifiable Diseases Surveillance System for each disease or condition.
National public health surveillance case definitions used by the National Notifiable Diseases Surveillance System	Surveillance case definitions are used to define what a ‘case’ of disease is for public health surveillance purposes. They also help ensure diseases and conditions are classified and enumerated consistently across jurisdictions.	CDC staff and the Council of State and Territorial Epidemiologists (CSTE, www.cste.org) collaborate to develop or revise national surveillance case definitions. Then, they are officially approved by CSTE. Surveillance case definitions include clinical, epidemiologic, and laboratory criteria to define what a ‘case’ of a specific disease or condition represents.