The ICD-9 is the International Classification of Diseases, ninth revision, covering the years 1979 to 1998. The codes in this publication represent all diseases, conditions or circumstances known to cause a person's death. Managed by the World Health Organization, these codes exist as the standard used in medical records for conditions diagnosed globally. Medical personnel handling billing, insurance, health records and statistics are expected to remain up to date with the ever-changing ICD standards, with minor updates made annually and major revisions published each decade. While the ICD-10 was published in 1998 and placed in effect in 2007 as the current database of disease classification used for health records, reimbursement systems and public data, many hospitals still use the ICD-9 today.
The ICD codes originated in France in 1893 when physician Jacques Bertillion developed a coding system called the Bertillion Classification of Causes of Death. This first version of codes were brought to the United States in 1898 and are considered ICD-1. With the progression of medical science and the development of new diagnoses, the ICD lists have been updated now to the tenth revision. Minor annual updates are made, with revisions to the code set being published only as major medical updates require these expensive changes to be made. One example is the ICD-6 upgrade in 1949 when mental disorders were first added to the code set, requiring the entire list to be revised.
ICD codes have different variations and functions. These codes are applied internationally, with the two letters at the end used to record which country they come from. ICD-CM codes are used for diagnosis, CM meaning "clinical modification." These codes remain on a patient's records, and as electronic systems are further developed these codes become more important. ICD codes are also used by government health authorities to track certain diseases, especially those that are highly contagious or of great public interest. Authorities use ICD codes to track how the diseases spread and where they are prevalent, and then develop budgets and research programs. ICD codes also record causes of death as listed on death certificates.
Each diagnosis we receive as a patient is given a code that remains on our medical records, though they do not affect our future care if the disease is treatable. However, chronic problems like heart disease and diabetes will stay on one's record throughout life, affecting medical care and billing, altering the determinations made by medical providers about our care. The implementation of electronic medical records across the country is allowing for more widespread use of these codes, and the updates are becoming more important.
Additional Types of Codes
In addition to diagnosis, ICD-CM codes have related CPT-- Current Procedural Terminology -- codes. These five-digit codes describe all different medical procedures and services offered by health care providers. They are published by the American Medical Association, now in the fourth edition, providing standard criteria applicable to medical billing. CPT codes hold a critical relationship with the ICD-9 coding system in ensuring that patients are billed for services related to conditions for which they have been diagnosed.
Revisions of the ICD Codes
Revisions of the ICD codes are published approximately every decade, with updates made annually. Medical personnel are expected to keep up to date with these revisions as they are published and implemented. Since "upgrading" to the next update is an expensive transition, many hospitals around the world still refer to the ICD-9 coding system in their electronic databases, which is likely why this is still the standard terminology still used for medical coding. The ICD-11 is expected for publication in 2010 and implementation around 2015.