Like its predecessor ICD-9-CM, ICD-10-CM is based upon the International Classification of Diseases, which is published by the World Health Organization (WHO) and which uses unique alphanumeric codes to identify known diseases and other health problems. According to WHO, physicians, coders, health information managers, nurses and other healthcare professionals also use ICD-10-CM to assist them in the storage and retrieval of diagnostic information. ICD records are also used in the compilation of national mortality and morbidity statistics.
The ICD-10-CM revision includes more than 68,000 diagnostic codes, compared to 13,000 in ICD-9-CM. In addition, ICD-10-CM codes include twice as many categories. ICD-10-CM diagnosis codes consist of three to seven digits, compared to the three to five digit system of ICD-9-CM. The increase in the amount and length of ICD-10-CM codes will allow for greater coding specificity.
Despite not being used in American hospitals, the ICD-10-CM code set has been revised yearly since 2003 to keep up with alterations made to ICD-10 by WHO. In preparation for ICD-10-CM implementation, a partial code freeze stopped the regular annual updates to ICD-10-CM codes in October 2011. Since then, there have been limited yearly changes made to the ICD-10-CM coding set with the normal updates scheduled to resume in 2016.