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ICD-10 Coding Changeover

What is it?
What does it mean for my practice?
What are some additional resources?

What is it?

The International Statistical Classification of Diseases (ICD) is the international standard diagnostic classification for all general epidemiological, health and clinical use. It is a coding and classification system of diseases, signs and symptoms, abnormal findings, complaints, social circumstances and external causes of injury or diseases, as determined by the World Health Organization (WHO).

The first edition, known as the International List of Causes of Death, was adopted by the International Statistical Institute in 1893. The WHO took over the responsibility for the ICD at its creation in 1948 when the Sixth Revision was published, which included causes of morbidity for the first time.

Developed almost 35 years ago, ICD-9 is now widely viewed as outdated because of its limited ability to accommodate new procedures and diagnoses that have developed since its implementation. ICD-9 contains only 17,000 codes. By contrast, the ICD-10 code sets contain more than 155,000 codes, including a host of new diagnoses and procedures, and more adequately reflecting the current state of medicine.

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. The United States government delayed transition to the ICD-10 system due to concerns about the impact of the transition on the health system and economy, among others.

In 2008, The Department of Health and Human Services (HHS) announced that it would begin the process for adopting ICD-10 code sets by October 2011. However, the proposed implementation was delayed a further two years following receipt of extensive public comments objecting to the proposal, and its originally planned timeline.

The United States will begin official use of ICD-10 on October 1, 2015. All HIPAA-covered entities must make the change.

What does it mean for my practice?

The ICD-10 transition will require systems and business changes throughout the health care industry. The change will affect coding for everyone covered by the Health Insurance Portability and Accountability Act (HIPAA), not just those who submit Medicare claims.

ICD-10 codes must be used on all HIPAA transactions, including outpatient claims with dates of service, and inpatient claims with dates of discharge on and after October 1, 2015. Otherwise, claims and other transactions may be rejected, and will need to be resubmitted with the ICD-10 codes. This could result in delays and impact to your reimbursements, so it is important to start now to prepare for the changeover to ICD-10 codes.

This change does not affect CPT coding for outpatient procedures.

On January 1, 2012, standards for electronic health care transactions change from Version 4010/4010A1 to Version 5010. These electronic health care transactions include functions like claims, eligibility inquiries, and remittance advices. Unlike the current Version 4010/4010A1, Version 5010 accommodates the ICD-10 codes, and must be in place first before the changeover to ICD-10. The Version 5010 change occurs well before the ICD-10 implementation date to allow adequate Version 5010 testing and implementation time.

To accommodate the ICD-10 code structure, the transaction standards used for electronic health care claims, Version 4010/4010A, must be upgraded to Version 5010 by January 1, 2012.

If providers do not conduct electronic health transactions using Version 5010 as of January 1, 2012, delays in claim reimbursement may result. If health plans cannot accept Version 5010 transactions from providers, they may experience a large increase in provider customer service inquiries affecting their operations.

Preparing for ICD-10 and Version 5010 – including potential updated software installation, staff training, changes to business operations and workflows, internal and external testing, reprinting of manuals and other materials, and more – will take time. CMS has constructed a timeline for providers to begin implementing, testing, and changing over to the new Version 5010 claims system. See the timeline, and other helpful information here.

According to that timeline, providers should already have begun external testing of Version 5010 for electronic claims.

What are some additional resources?

Compliance timelines, materials from CMS-sponsored calls and conferences, and links to resources are available here. Check link often for the latest information and updates from CMS.

CMS hosts National Provider Conference Calls where providers can learn about how ICD-10 will affect their practices.


Visit CMS  "Road to 10" for smaller physician practices with primers for clinical documentation, clinical scenarios, and other specialty-specific resources.


Visit the AMA Wire for a broad range of materials available to help physicians prepare for the October 1st deadline.