Big Differences Between Three ICD-10 Coding Systems

Here are some interesting facts about ICD-10 that may not be commonly known.

International Classification of Diseases (ICD) was created by the World Health Organization (WHO), which has served the healthcare community for over a century. While most industrialized countries moved to the ICD’s “tenth revision” – ICD-10 – 30 years ago (1983), the United States only transitioned in October 2015.

There are differences, however, between what WHO publishes and what the US actually utilizes.

WHO’s ICD-10 classification system is for diagnosis codes only, and does not contain any procedural codes.

ICD-10-CM (Clinical Modification) is a US clinical modification of WHO’s ICD-10, developed to support US health information needs. ICD-10-CM is designed for classifying and reporting diseases in all US healthcare settings. WHO gave the US permission for these modifications.  I have not been able to find out why these modifications were made or what specifically was modified, but the technology systems of US healthcare organizations that operate internationally – either now or in the future – will need to accommodate for both the US ICD-10-CM codes and the WHO’s standard ICD-10 codes.

ICD-10-PCS (Procedure Classification System) was developed by the Centers for Medicare & Medicaid Services (CMS) and is not based on WHO’s coding system. ICD-10-PCS replaced the ICD-9-PCS and are only required for facilities reporting procedures on hospital inpatient services.

When speaking of these new classifications in the US, the term “ICD-10” is often used for both code sets (ICD-10-CM and ICD-10-PCS), but it is important to understand that they serve very different purposes.

…On the forefront, WHO has already released a BETA version of ICD-11.