ICD-9 is an acronym used in the medical field that stands for International Classification of Diseases, ninth revision. In the United States, the ICD-9 covered the years 1979 to 1998. Currently, ICD-10, which is the tenth revision, is in effect as the most current database of disease classifications. ICD-9 was used in the US until the 10th revision became fully implemented in 1998, though the actual revision was concluded some years earlier.
The ICD is used to provide a standard classification of diseases for the purpose of health records. The World Health Organization (WHO) assigns, publishes, and uses the ICD to classify diseases and to track mortality rates based on death certificates and other vital health records. Medical conditions and diseases are translated into a single format with the use of ICD codes. The current ICD-10 varies slightly from the previous ICD-9 and includes almost double the number of categories in a total of three volumes.
Current ICD classifications are alphanumeric codes that represent any known disease, condition, or circumstance that has or could cause a person’s death. The classifications are as specific as possible. For example, cancer is a leading cause of death, but the ICD provides a specific classification for each type of cancer, from lung cancer to breast cancer and so forth. Further, there are ICD classifications assigned to deaths not caused by disease, such as suicide, homicide, and accidental death. The September 11 attacks on the United States prompted further classifications for death by terrorism.
Many of the ICD-9 codes remain unchanged in the newest revision, and only where it became necessary to further classify or provide new classifications did the ICD-9 change. Individuals in the healthcare profession who manage health information and records must constantly keep abreast of the changes and modifications applied to the ICD.
The ICD has been in use since its inception in 1900. It is updated annually with minor revisions and every three years with major revisions, and it is republished in a fully revised version every ten years. It has been published by the WHO since 1970. The United States Department of Health and Human Services publishes their own further indexed version of the ICD to include diagnostic and operative procedures, which at present is ICD-9-CM, meaning clinically modified. In addition to statistics and mortality rates, the ICD is used for health records, reimbursement systems, and public data.