There are two related classifications of diseases with similar titles, and a third classification on functioning and disability. The ICD is the classification used to code and classify mortality data from death certificates. The ICD, Clinical Modification (ICD-9-CM) is used to code and classify morbidity data from the inpatient and outpatient records, physician offices, and most National Center for Health Statistics (NCHS) surveys. NCHS serves as the World Health Organization (WHO) Collaborating Center for the Family of International Classifications for North America and in this capacity is responsible for coordination of all official disease classification activities in the United States relating to the ICD and its use, interpretation, and periodic revision.

In 1893, a French physician, Jacques Bertillon, introduced the Bertillon Classification of Causes of Death at the International Statistical Institute in Chicago.

A number of countries adopted Dr. Bertillon's system, and in 1898, the American Public Health Association (APHA) recommended that the registrars of Canada, Mexico, and the United States also adopt it. The APHA also recommended revising the system every ten years to ensure the system remained current with medical practice advances. As a result, the first international conference to revise the International Classification of Causes of Death convened in 1900; with revisions occurring every ten years thereafter. At that time the classification system was contained in one book, which included an Alphabetic Index as well as a Tabular List. The book was small compared with current coding texts.

Version 9 of the ICD and Health Related problems (ICD-9) was used until the end of 1994 when version 10 was introduced.

ICD10 is a substantial revision of the coding classification and there is not always a single equivalent code in ICD10 for a code in ICD9.

NOTE: The ICD-9 codes are still primarily use in the United States, while the ICD-10 codes are being used most else where.  This program will allow Health-Care Entities (Providers, Clearing Houses, Payers) and other organizations to easily migrate to the newer version.

Section 503(a), which includes a requirement for updating the ICD-9-CM diagnosis and procedure codes in April 1 of each year, in addition to the current process of annual updates on October 1 of each year. This change will not affect Medicare payments or DRG classifications until the fiscal year that begins after that date.

The ICD-9-CM Coordination and Maintenance Committee will implement a partial freeze of the ICD-9-CM and ICD-10 (ICD-10-CM and ICD-10-PCS) codes prior to the implementation of ICD-10 on October 1, 2013. There was considerable support for this partial freeze. The partial freeze will be implemented as follows:

• On October 1, 2011, the last regular, annual updates to both ICD-9-CM and ICD-10 code sets will be made.
• On October 1, 2012, there will be only limited code updates to both the ICD-9-CM and ICD-10 code sets to capture new technologies and diseases as required by section 503(a) of Public Law 108-173.
• On October 1, 2013, there will be only limited code updates to ICD-10 code sets to capture new technologies and diagnoses as required by section 503(a) of Pub. L. 108-173. There will be no updates to ICD-9-CM, as it will no longer be used for reporting.
• On October 1, 2014, regular updates to ICD-10 will begin.

The first (alpha) draft of the ICD-11 system (authored by WHO) was on May 10, 2010, with a beta draft due May 10, 2011. The final draft will be submitted to World Health Assembly (WHA) by 2014. Pilot implementation is scheduled to begin in March 2014. The ICD revision process is open to all comers willing to register, back their suggestions with evidence from medical literature and participate in online debate over proposed changes through an ICD Update and Revision Platform extranet. WHO is using Web 2.0 principles for the first time to revise ICD via a multi-author drafting platform known as the Initial ICD-11 Collaborative Authoring Tool (iCAT). The iCAT production server had been viewable by all, but in November 2010 editing rights were restricted to WHO, Revision Steering Group, Topic Advisory Groups and external peer reviewers of proposals and content until the beta draft stage is reached. More detailed information on the revision process, access to the revision platform and iCAT is available at the WHO website.

ICD Revision Timelines

 May 2011: Open ICD-11 Alpha Browser to the public for viewing

 July 2011: Open ICD-11 Alpha Browser to the public for commenting

 May 2012: Open ICD-11 Beta to the public

 ICD-11 Beta Information

 WHO will engage with interested stakeholders to participate in the ICD revision process.

 Individuals will be able to:

 Make comments

 Make proposals to change ICD categories

 Participate in field trials

 Assist in translating

 May 2015: Present the ICD-11 to the World Health Assembly