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Overview of ICD-11

By AGS Health

December 21, 2022

Understanding ICD-11

International Classification of Diseases (ICD) is the global standard for recording health information and causes of death. It is developed and updated annually by the World Health Organization (WHO). ICD-11 was presented at the World Health Assembly on March 25, 2019 and approved for implementation on January 1, 2022, which means all countries have access to it and the ability to implement ICD-11 in accordance with their own timetables.

Clinicians, statisticians, and classification and IT experts from around the world collaborated to develop the 11th edition, which was a first for ICD development and extremely beneficial for the medical community. The inclusion of these groups resulted in an increase in the number of diagnoses from 14,400 in ICD-10 to 55,000 unique codes in ICD-11, giving researchers and healthcare organizations access to more complete healthcare information. Given the significant changes, the WHO has acknowledged many countries will be slow to transition to ICD-11.

Each country can either adopt the code set as is or customize it to meet the individual needs of their country’s healthcare reporting system. In the U.S., ICD is customized through clinical modifications (the CM in ICD-10-CM) to allow it to be tied to provider reimbursements.

What is different with ICD-11?

ICD-10 is more than 25 years old. As such, there are major factors contributing to the need for a new edition, including:

  • Substantial advancements in medicine and the science of disease that have occurred over the past 30 years
    • ICD-10 is outdated both clinically and from a classification perspective
    • Substantial structural changes were needed to some chapters
    • Changes could not be handled under the normal ICD-10 updating mechanism
    • Changes needed were well beyond a major update
  • There was an increasing need for an electronic environment
  • Need to capture more information, especially for morbidity use cases

Ultimately, the decision was made in 2007 to begin work on a new edition. ICD-11 addresses gaps and problems, such as:

  • Antimicrobial resistance - essentially missing in ICD-10
  • HIV subdivisions - outdated detail in ICD-10
  • Simplified Diabetes coding
  • Skin cancer - melanoma types missing – basalioma missing in ICD-10
  • Valve diseases - outdated structure, need by valve, less rheumatic
  • Postprocedural conditions - clarify when using 19 and when not for postprocedural
  • Cancers with histopathology – ICD-O for cancer registries embedded
  • External causes – better coding traffic accidents

Other major differences between ICD-10 and ICD-11 include:

  • Codes look different – Alzheimer disease
    • ICD-10 – G30
    • ICD-11 – 8A20
  • Simplified code structure
    • Extension codes (e.g., temporality, severity, dimensions of injury and external causes)
    • Clustering of codes – combining 2 or more codes to describe a diagnostic entity
  • Some diseases changed locations
  • Six new chapters
    1. Diseases of blood and blood-forming organs
    2. Disorders of the immune system
    3. Conditions related to sexual health
    4. Sleep-wake disorders
    5. Extension codes
    6. Traditional medicine

On February 11, 2022, the WHO claimed 35 countries were using ICD-11. In the U.S., the implementation timeline is unknown; however, implementation discussions are underway.

The eleventh revision contains around 17,000 unique codes, more than 120,000 codable terms and is entirely digital.

Understanding of ICD-11

A Brief History of ICD

The first ICD edition was adopted by the WHO back in 1900, and it was used in the U.S. for mortality between 1900-1909. It evolved over time and has become a comprehensive classification system used in mortality, morbidity, as well as case mix, quality measures, patient safety, and more. It’s used mainly in primary care, secondary care, and research. ICD also records, reports, and groups conditions. The most widespread use for ICD is for the cause of death statistics or mortality. These statistics are used for research, public health monitoring, evaluating health interventions, and planning follow-up health care.

How was ICD-11 developed?

The classification system underwent a significant redesign, involving more than 300 specialists from 55 countries and 30 workgroups. More than 10,000 proposals were submitted from around the world to the WHO for consideration.

ICD-11 is a vast improvement on previous revisions. It reflects critical advances in science and medicine, alarming classifications with the latest knowledge of disease treatment and prevention – delivering more meaningful clinical data than ever before.

These changes range from being more informational, technology-friendly, and better able to support data collection and morbidity to lowering costs. WHO wanted to bring ICD-11 into the 21st century and make it a completely digital design and easily integrated with electronic health applications and information systems. It does a better job of capturing quality and safe healthcare data and is much more user-friendly. These advancements made ICD-11 more intricate and comprehensive than its predecessors.

It is also capable of linking ICD-11 with other classifications, for example, the International Classification of Functioning Disability and Health. For the first time, ICD-11 will enable dual coding of traditional medicine diagnosis alongside mainstream medicine and now also permits the generation of a functioning score based on the WHO Disability, Assessment Schedule.

It will also be a multilingual reference already translated into English, Russian, Chinese, Spanish, Arabic, and French.

ICD-11 in the U.S.

The Secretary of Health and Human Services (HHS) has given the U.S. an expected implementation year of 2025. But, if a clinical modification is needed, it could be postponed to 2027.

The National Center for Vital and Health Statistics (NCVHS) notes numerous steps towards implementation:

  • First, we need to evaluate the ICD-11 for U.S. purposes beginning in 2022.
  • National Committee on Vital and Health Statistics hearings are needed to discuss ICD-11 and make any required revisions.
  • Then, the notice of proposed rulemaking from HHS needs to be published in the Federal Register.
  • Finally, the Final Rule would have to be published in the Federal Register.

Not only does the above need to occur prior to computer system updates, but coders have to be educated as well. As of now, the final implementation date in the U.S. remains unknown.

Structural Changes

ICD-11 features several new chapters, including:

  • Diseases of the immune system
  • Sleep-wake disorders
  • Conditions related to sexual health
  • A new supplementary chapter, referred to as traditional medicine conditions

The codes are presented in alphanumeric order, covering the range from 1A00.00 to ZZ9Z.ZZ. There is always a letter in the second position and a new feature will be referred to as cluster coding. It is fully electronic and provides access to 17,000 categories with over 100,000 medical diagnostic index terms.

There is also a foundational component. This data source for the production and maintenance use of classification includes additional content that goes beyond the traditional paper-based use of classification and links to other classification terminology, which will be expanded in the future.

The stem codes of ICD-11 are organized in 26 chapters that follow the traditional pattern of ICD, relating to etiology, the organ system, maternal status, perinatal status, external causes, and factors influencing health status. While stem codes may be reported alone, they may also be reported in conjunction with an extension code or even other stem codes. And so, we’ll see linking of codes, referred to as post-coordination, allows the codes to describe documented conditions fully. The ability to post-coordinate codes will help the code set to be organized and provide a way to capture all the detail without exploding the code set with sometimes hundreds of additional codes to include every combination.

Other Significant Changes: ICD-10 to ICD-11

In ICD-10, the chapter numberings were roman numerals. In ICD-11, it is Arabic. We also have three character categories in ICD-10; in ICD-11, a category is referred to as a “Stem Code” with four characters.

Both code sets have alphanumeric codes so you see a letter in the first position and a number in the second, third, and fourth positions. In ICD-10, the first character of the code is a letter, but in ICD-11, we see a code starting with an “X” indicates an extension code, as well as the letters “O” and “I” are omitted to prevent confusion with the numbers “0” and “1.”

The ICD-11 code set supports post-coordination and linking codes within the code clusters.

Next Steps

Health organizations should identify someone to monitor industry updates surrounding ICD-11. It’s important for HIM professionals to stay current about ICD-11, which will help ensure a smooth transition.

With the exact implementation date in question, there’s much uncertainty about how to plan and prepare. Right now, the best solution is to stay current and keep teams updated.

For more information, watch our webinar on Overview of ICD-11 by coding expert Leigh Poland, covering everything from the latest revision of the ICD to implementation and key differences.

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