The International Classification of Diseases, Ninth Revision, Clinical Modification, ICD-9-CM, is a classification system that groups related disease entities and procedures for the reporting of statistical information. The clinical modification of the ICD-9 was developed by the National Center for Health Statistics for use in the United States. 

The ICD-9-CM consists of : 

• a tabular list containing a numerical list of the disease code numbers in tabular form, 
• an alphabetical index to the disease entries, 
• and the classification system for surgical, diagnostic, and therapeutic procedures (this last section is not part of the international version of ICD) 

ICD-9-CM uses: 

• Classify morbidity and mortality information for statistical purposes 
• Indexing of hospital records by disease and operations 
• Reporting of diagnosis by physicians 
• Data storage and retrieval 
• Tool in reporting national morbidity and mortality data 
• Basis of DRG for hospital reimbursement 
• Reporting and compiling of health care data to assist in 
  • evaluating the appropriateness and timeliness of medical care 
  • planning health care delivery systems o determining patterns of care among health care providers o analyzing payments for health services
  • conducting epidemiological and clinical research ICD-9-CM

Maintenance: 

Responsibility for maintenance of the classification system is shared between the National Center for Health Statistics, or NCHS (diagnosis classification) and the Health Care Financing Administration, or HCFA (procedure classification). NCHS and HCFA co-chair the ICD-9-CM Coordination and Maintenance Committee. Established in 1985, the committee was formed to provide a public forum to discuss possible updates and revisions to the ICD-9-CM. Committee meetings are held twice a year. Suggestions for modifications come from both the public and private sectors. Suggestions for modifications are submitted prior to a scheduled meeting. The meetings are open to the public and comments are encouraged at the meeting and in writing. No decisions are made at the meetings. The committee's role is advisory. All final decisions are made by the Director of NCHS and the Administrator of HCFA. Final decisions are made after the December meeting and become effective October 1 of the following year. 

Official code revision packages, referred to as addenda, are published each year prior to October 1 effective date and are made available to the public in several ways. New codes and code extensions are published in the Federal Register. Modifications to the alphabetic index and revisions of notes are found only in the addenda. The entire addenda is published in Coding Clinic for ICD-9-CM.