International Classification of Diseases (ICD)

What Is ICD-9 & ICD-10?

ICD stands for the International Classification of Diseases (ICD). The ICS is the oldest method of tracking diseases and mortality in the world. Developed in Europe, several versions have evolved over time. The first edition was known as the International List of Causes of Death, and was adopted by the International Statistical Institute in 1893.

ICD-9 is the original diagnostic coding system that was implemented by the World Health Organization (WHO). ICD-10 is a new generation diagnostic coding system that was implemented in 1993 to replace ICD-9. ICD-10 is used by almost every country in the world today, except for the United States. This code set is scheduled to replace ICD-9-CM, our current U.S. diagnostic code set, on Oct. 1, 2013.

Another designation, ICD-10-PCS, for “procedural coding system,” will also be adopted in the United States in 2013. ICD-10-PCS will replace Volume 3 of ICD-9-CM as the inpatient procedural coding system. The final rule stated that CPT would remain the coding system for physician services.

Why Is The U.S. Moving To ICD-10-CM?

ICD-9-CM has several problems. For starters, it is running out of room quickly!

Because ICD-9-CM is organized scientifically, each 3-digit category can have only 10 subcategories. Currently, almost all numbers in all categories have been assigned codes.

As medical science continues to grow and make new discoveries, we are in need of a larger coding system that will enable us to assign diagnoses.

How Is ICD-10-CM Different From ICD-9-CM?

ICD-10-CM and ICD-9-CM are quite similar! The organization of the codes, guidelines, conventions, and rules are all very similar. Anyone who is qualified to code ICD-9-CM should be able to easily make the transition to ICD-10-CM.

The big differences between the two systems are differences that will affect information technology and software at your practice. Here’s a chart showing the differences:

Issue	ICD-9-CM	ICD-10-CM
Volume of codes	Approximately 13,600	Approximately 69,000
Composition of codes	Mostly numeric, with E and V codes alphanumeric. Valid codes of 3, 4, or 5 digits.	All codes are alphanumeric, beginning with a letter and with a mix of numbers and letters thereafter. Valid codes may have 3, 4, 5, 6 or 7 digits.
Duplication of code sets	Currently, only ICD-9-CM codes are required. No mapping necessary.	For a period of 2 years or more, systems will need to access both ICD-9-CM codes and ICD-10-CM codes as the country transitions from ICD-9-CM to ICD-10-CM. Mapping will be necessary so that equivalent codes can be found for issues of disease tracking, medical necessity edits and outcomes studies.

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