What Do ICD Codes Mean?

ICD codes are part of an internationally recognized system for describing diseases, symptoms and medical conditions. The most recent version allows more than 12,000 codes.

Administration

• ICD stands for "International Classification of Diseases." The system is maintained by the World Health Organization of the United Nations.

Significance

• Standardizing the identification of diseases and conditions allows for better comparison of health statistics among countries and better coordination of public health efforts.

Systems

• The most recent version of the system is ICD-10. It allows for about twice as many codes as its predecessor, ICD-9, which had been running out of codes. Most countries use only ICD-10; the United States uses both.

In the U.S.

• The U.S. health-care system uses ICD-9 for classifying "morbidity"--diseases and conditions in living people--and ICD-10 for classifying "mortality"--cause of death. The federal government has required ICD-9 codes on all Medicare and Medicaid claims, which has hampered adoption of ICD-10.

Differences

• The ICD-9 system allows for up to five digits, all of them numerals, while ICD-10 allows for up to six characters, the first of which is a letter. The systems' codes are radically different. An asthma attack, for example, is "493.92" in ICD-9, but in ICD-10, it could be "J45.21," "J45.41" or "J45.51," depending on severity.

Identification

• See the links in the Resources section for searchable databases of ICD codes.