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Short description: Diagnosis code system for use in the U.S.

The ICD-10 Clinical Modification (ICD-10-CM) is a set of diagnosis codes used in the United States of America .[1] It was developed by a component of the U.S. Department of Health and Human services,[2] as an adaption of the ICD-10 with authorization from the World Health Organization. In 2015, ICD-10-CM replaced ICD-9-CM as the federally mandated classification. Annual updates are provided.


Since 1979, the US had required ICD-9-CM codes[3] for Medicare and Medicaid claims, and most of the rest of the medical industry in the US followed suit. On January 1, 1999, the ICD-10 (without clinical extensions) was adopted for reporting mortality, however, ICD-9-CM continued to be used for morbidity.

During that time, the U.S. National Center for Health Statistics (NCHS) received permission from the WHO to create a clinical modification of the ICD-10.

ICD-10-CM adapted ICD-10 in the following ways:[citation needed]

  • Allow the capture of information for ambulatory and managed care encounters
  • Expand available injury codes
  • Combine codes for diagnosis/symptoms to reduce the number of codes needed to describe a problem fully
  • Provide additional sixth and seventh digit classifications
  • Add classifications specific to laterality
  • Refine classification for increased data granularity


Adoption of ICD-10-CM was slow. On August 21, 2008, the US Department of Health and Human Services (HHS) proposed new code sets to be used for reporting diagnoses and procedures on health care transactions. Under the proposal, the ICD-9-CM code sets would be replaced with the ICD-10-CM code sets, effective October 1, 2013. On April 17, 2012, the Department of Health and Human Services (HHS) published a proposed rule that would delay the compliance date for the ICD-10-CM and PCS by 12 months-from October 1, 2013, to October 1, 2014.[4] Congress further delayed the implementation date to October 1, 2015, after it was inserted into the "Doc Fix" Bill without debate over the objections of many.[citation needed]


On October 1, 2015, ICD-10-CM replaced volumes 1 and 2 of ICD-9-CM, and ICD-10-PCS replaced volume 3.

Annual review

The ICD-10-CM code set is reviewed every year.[5] The code set for the 2023 fiscal year applies to patient discharges and encounters between October 1, 2022, and September 30, 2023 (inclusive)[6][needs update?] – with the exception of four codes that were in effect from April 1, 2022.[6]


  1. Cartwright, Donna J. (December 2013). "ICD-9-CM to ICD-10-CM Codes: What? Why? How?". Advances in Wound Care 2 (10): 588–592. doi:10.1089/wound.2013.0478. ISSN 2162-1918. PMID 24761333. 
  2. "About NCHS - Organization" (in en-us). 2023-02-04. "The National Center for Health Statistics is part of the Centers for Disease Control and Prevention, Department of Health and Human Services." 
  3. International Classification Of Diseases - 9 - CM, (1979). Retrieved on 2014-06-20.
  4. "Classification of Diseases, Functioning, and Disability". U.S. Centers for Disease Control. 
  5. "ICD - ICD-10-CM - International Classification of Diseases,(ICD-10-CM/PCS Transition" (in en-us). March 3, 2022. "Like ICD-9-CM codes, ICD-10-CM/PCS codes will be updated every year" 
  6. 6.0 6.1 Harry, Azia J. (September 18, 2022). "ICD-10-CM FY 2023 Diagnosis Code Updates". Journal of AHIMA. Retrieved January 5, 2023. 

See also