The International Classification of Diseases (ICD)

The International Classification of Diseases (ICD)

In the medical coding field ICD coding is the backbone of medical coding. International Classification of Diseases is necessary to transforming descriptions of diagnosis and procedures into universal acceptable medical code numbers.

The International Classification of Diseases (ICD) is the standard diagnostic tool for epidemiology, health management and clinical purposes. This includes the analysis of the general health situation of population groups. It is used to monitor the incidence and prevalence of diseases and other health problems, proving an image of the general health condition of countries and populations.

Physicians, nurses, health information managers and coders, researchers, health information technology workers, policy-makers, insurers and patient organizations are using ICD to classify diseases and other health problems recorded on many types of health and vital records, including death certificates and health records. In addition to enabling the storage and retrieval of diagnostic information for clinical, epidemiological and quality purposes, these records also provide the basis for the compilation of national mortality and morbidity statistics by WHO Member States. Finally, ICD is used for reimbursement and resource allocation decision-making by countries.

ICD-10 is the 10th revision of the International Classification of Diseases and Related Health Problems (ICD). ICD-10 was endorsed by the Forty-third World Health Assembly in May 1990 and came into use in WHO Member States as from 1994. ICD is currently under revision, through an ongoing Revision Process, and the release date for ICD-11 is 2017.

Difference between ICD-9 and ICD-10

The ICD-10 code sets have basic changes in structure and concepts that make them very different from ICD-9. Like, ICD-9 is the lack of specificity of the information conveyed in the codes. For example: If a patient is seen for treatment of a burn on the left leg, the ICD-9 diagnosis code does not distinguish that the burn is on the left leg. If the patient is seen a few weeks later for another burn on the right leg, the same ICD-9 diagnosis code would be reported. Additional documentation would likely be required for a claim for the treatment to explain that the burn treated at this time is a different burn from the one that was treated previously. In the ICD-10 diagnosis code set, characters in the code identify right versus left, initial encounter versus subsequent encounter, and other clinical information.

One more problem with ICD-9 is that some chapters are full and there is no scope to add new codes. In some cases, new codes have been assigned to different chapters making it difficult to find all available codes. ICD-10 codes have increased character length, which very much expands the number of codes that are available for use. With more available codes, it is less likely that chapters will run out of codes in the future.

The following tables provide a comparison of the features of the ICD-9 and ICD-10 diagnosis code sets.

ICD-9 ICD-10
3-5 characters in length 3-7 characters in length
Approximately 13,000 codes Approximately 68,000 available codes
First digit may be alpha (E or V) or numeric;digits 2-5 are numeric Digit 1 is alpha; digits 2 and 3 are numeric;digits 4-7 are alpha or numeric




Many countries use ICD-10 for reimbursement and resource allocation in their health system.

For example: Australia, Canada, China, France, Germany, Korea, and South Africa etc.

United States is still using ICD-9, the deadline for the United States to begin using ICD-10 for diagnosis coding and Procedure Coding System ICD-10-PCS for inpatient hospital procedure coding is set at October 1, 2015.

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