International Classification of Diseases ninth revision
International Classification of Diseases ninth revision (ICD-9) is a medical code set that is maintained by the World Health Organization (WHO). The primary purpose of this code set is to classify causes of death. It is a U.S. extension that is maintained by the National Center for Health Statistics within the Centers for Disease Control and Prevention (CDC) and identifies morbidity factors or diagnoses. The ICD-9-CM (clinical modification) codes have been selected for use in HIPAA transactions.