Health United States 2020-2021

International Classification of Diseases, Clinical Modification (ICD–CM)

Based on, and compatible with, the World Health Organization’s ICD. ICD–CM is used to code and classify morbidity diagnoses and inpatient procedures.

International Classification of Diseases, Ninth Revision, Clinical Modification

(ICD–9–CM)—ICD–9–CM was used until October 1, 2015, when the International Classification of Diseases, 10th Revision, Clinical Modification (ICD–10–CM) went into effect.

ICD–9–CM chapters are arranged primarily by body system, with some additional chapters for other conditions (such as Infectious and parasitic diseases and Neoplasms) and two supplemental classifications for factors influencing health status and contact with health services (V codes), and for external causes of injury and poisoning.

International Classification of Diseases, 10th Revision, Clinical Modification (ICD–10–CM)

Implemented October 1, 2015. The transition to ICD–10 is required for everyone covered by the Health Insurance Portability and Accountability Act. ICD–10–CM far exceeds its predecessors in the number of concepts and codes provided. The disease classification has been expanded to include health-related conditions and to provide greater specificity at the sixth- and seventh-character level. The greater level of detail in the new code sets includes severity and complexity of disease conditions; more detailed coding of injuries, poisonings, and external causes; and new concepts that did not exist in ICD–9–CM, such as blood type and the Glasgow Coma Scale.

For more information about ICD–10–CM, see the National Center for Health Statistics “Classification of Diseases, Functioning, and Disability” website at: and the Centers for Medicare & Medicaid Services ICD–10 transition website at: (Also see Sources and Definitions, International Classification of Diseases [ICD].)

Page last reviewed: August 12, 2022