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What is ICD-11? An Overview

By DeVry University

The information presented here is true and accurate as of the date of publication. DeVry’s programmatic offerings and their accreditations are subject to change. Please refer to the current academic catalog for details.

December 7, 2021

8 min read

What is ICD-11? The International Classification of Diseases (ICD) was created by the World Health Organization (WHO) as a globally recognized diagnostic tool for epidemiology, health management and clinical purposes. The number 11 in ICD-11 indicates that healthcare organizations in the United States and other WHO member states currently follow the 11th revision of the ICD, which took effect on January 1, 2022. This revision captures the significant progress made in science and medicine over the past 30 years, reflects modern societal norms and transforms the way conditions are classified and coded in the clinical setting.

Goals of ICD-11

Our "what is ICD-11" discussion would not be complete without examining the purpose of this update. The WHO and its decision-making body, the World Health Assembly, realized that despite the updating process, ICD-10-CM (International Classification of Diseases, Tenth Revision, Clinical Modification) was clinically and technologically outdated and missing content for several de facto uses of ICD, like primary care or clinical decisions. To bring the system into the 21st century, structural changes were needed, as well as the need to operate in today’s environment of electronic medical records and capture more information for morbidity use cases.

According to the U.S. Centers for Disease Control and Prevention, the goals of this 11th ICD revision also included ensuring that ICD-11 will be a digital product, functioning in an electronic health records environment and linking with terminologies like SNOMED (Standardized Nomenclature of Medicine).

What’s Different in ICD-11?

Simply stated, the classification system has undergone a major makeover. It is now structured as a database that can include more than a dozen dimensions, with changes that range from making it more IT-friendly and better able to better support data collection on morbidity, to lowering cost. There’s also been a name change. Its full name is ICD-11 for Mortality and Morbidity Statistics, or ICD-11-MMS. Several changes have been made to the mental health disorders that are listed, including some that may be considered long overdue in the eyes of clinicians.

A partial list of additions and modifications includes:

    • Coding for antimicrobial resistance, which was missing in ICD-10, is included to enable data documentation and analysis consistent with the WHO Global Antimicrobial Resistance Surveillance System (GLASS).
    • A new classification for HIV has been created to account for the growing population of those living longer with the disease, providing the ability to link the virus with conditions, such as malaria, tuberculosis and dementia, among others.
    • New chapters on sleep-wake disorders and sexual health have been added.
    • Gender incongruence (gender dysphoria in the DSM) is no longer listed as a mental disorder but rather a sexual health condition. This change is intended to reduce the stigma that is associated with a psychological rather than a medical condition.
    • The section on personality disorders has been completely overhauled. As there was found to be much overlap in clinical practice, there is now a single diagnosis of “personality disorder” labeled as mild, moderate or severe, and measured in terms of 6 trait domain areas to retain some of the earlier specificity of diagnosis.

A couple of noteworthy features, like extensions and clustering, have the potential to improve ICD-11 code data. Extensions are non-diagnostic codes that add flexibility to the classification. They cannot be used alone, but rather are intended to be added to a stem code, replacing ICD-10 adjunct codes. Extension codes are appended to describe laterality, acuity, severity and other dimensions and external causes of injury.


Cluster coding, or combining two or more codes to describe a documented clinical concept, is how ICD-11 marks codes that are post-coordinated to describe one condition. When a diagnostic statement is broken down into its component parts for simplicity, clustering enables them to be linked in the coded record.


The AAPC, the nation’s largest education and credentialing organization for medical coders and billers, explains it this way:


Cluster coding refers to a convention where a “with” operator, either a forward slash or ampersand, is used to link ICD-011 codes together to create a diagnostic “sentence.”


For example:


Diagnosis: Duodenal ulcer with acute hemorrhage


Cluster: DA63/ME24.90&XA9780

    • DA63 is the condition (stem code) Duodenal ulcer
    • Has manifestation ME24.90 (stem code) Acute gastrointestinal bleeding, not elsewhere classified
    • Specific anatomy (extension code) XA9780 Duodenum

Advantages of ICD-11

What is ICD-11 in relation to the previous revision? According to AAPC, ICD-11 is a game-changer for the healthcare industry because it recognizes several common diagnoses that were overlooked in ICD-10. The addition of more than 40,000 new codes makes it a more complex system, but its advantages are many:

    • Ease of use when compared to previous versions. Coding is more contemporary and more easily integrated with electronic health records.
    • Completely electronic with a goal of user-friendliness.
    • Updated structure and content: Besides diseases, ICD-011 includes external causes, disorders, signs and symptoms, anatomy, histopathology and more.
    • Each category features 4 characters rather than 3, and there are 2 levels of subcategories, with a range of codes of 1A00.00 to ZZ9Z.ZZ.
    • Additional chapters for immune system diseases, sleep-wake disorders, traditional medicine, sexual health, developmental anomalies and functioning assessment.
    • Better representation of cancers, devices, medications, substances, severity and causes of injuries.
    • Allows for multiple applications to meet health system priorities. Examples include clinical recording, research, mortality, morbidity, primary care reporting, patient safety, antimicrobial resistance, resource allocation, epidemiology, public health, health system performance and reimbursement.

How Does ICD-11 Change Medical Billing and Coding?

Here's what the adoption of ICD-11 means for medical coders and billers:

It Includes More Diagnoses and Conditions

ICD-11 has added a significant number of diagnoses, increasing from 14,000 to more than 55,000 unique codes. The addition recognizes conditions not included in ICD-10, so medical coders and billers can become more granular and accurate in their submissions.

The new ICD-11 contains 26 chapters, 5 more than ICD-10. New sections cover diseases of the blood or blood-forming organs, disorders of the immune system, sleep-wake disorders, conditions related to sexual health and traditional medicine.

While some of the content is new, others were developed from existing chapters. For instance, many conditions in the sexual health chapter were previously classified under different categories. This means medical coders will need to take care to ensure that they're using the correct codes even for conditions they're familiar with.

It Increases Specificity and Flexibility

Medical codes will have 4 characters before the decimal point, instead of 3 like in ICD-10 and may contain up to 3 characters after the decimal point. The second position is always a letter, and additional codes add specificity to the base code (e.g., associated conditions). ICD-11 codes also exclude the letters "O" and "I" to avoid confusion with the numbers "1" and "0".

Medical coders and billers who work with specialty groups had to add a lot of codes to ICD-10. The new classification system in ICD-11 allows them to build codes that can accurately describe the conditions patients are being treated for, even if they still need to select an “unspecified” code.

Meanwhile, the alphanumeric coding structure allows more flexibility in diagnostic groupings. They are also updated to become more consistent with scientific evidence and align with clinical practice needs.

It Supports the Latest Technologies

ICD-11 enables healthcare organizations to streamline processes and increase operational efficiencies with the latest technologies. Instead of a static publication, it's built as a database and accessed as a web platform to support the use of electronic health records (EHRs). 

As such, it has the flexibility to grow and change as new scientific and medical discoveries emerge. The online content will evolve from the same basic structure so medical coders and billers won't have to adapt to yet another new version as the information is updated.

The ICD-11 platform also includes a robust search feature. For example, physicians can look up diagnoses using natural or preferred terminology. The system will then automatically match it with the correct technical code. This helps streamline workflows while increasing the accuracy of the coding process.

ICD-11 is designed to support interoperability. Healthcare organizations can use API to integrate the new database with their systems and software seamlessly. You can also link the digitized platform with various medical libraries to enhance its functionality.

Since ICD-11 will connect with most EHR systems through the Systematic Nomenclature of Medicine and Clinical Terms (SNOMED CT) Foundation, it will create changes in the coding system for most healthcare organizations.

To support the use of various e-health technologies, ICD-11 comes with many digital tools to help facilitate the medical coding and billing process. For instance, the implementation package includes a coding tool, reference guide, browser tool and transition tables.

Diagnoses Added to ICD-11

The launch of ICD-11 introduced a completely revised structure for the classification of mental and behavioral disorders. The following examples are representative of these updates.

Gaming Disorder

Gaming Disorder (GD) is defined in ICD-11 as a pattern of gaming behavior (digital or video-gaming) characterized by impaired control over gaming, increasing priority given to gaming over other activities to the extent that gaming takes precedence over other interests and daily activities and the continuation or escalation of gaming despite the occurrence of negative consequences.

The inclusion of GD in ICD-11, while highly debated, was based on reviews of available evidence and the need to standardize the disorder to make prevention and treatment measures readily available.

The established codes for GD are:

    • Gaming disorder, predominantly online: 6C51.0
    • Gaming disorder, predominantly offline: 6C51.1
    • Gaming disorder, unspecified: 6C51.Z

Complex PTSD

Complex post-traumatic stress disorder, or Complex PTSD, is defined as a disorder that may develop following exposure to prolonged or repetitive events of a particularly threatening or horrific nature. This may include things like prolonged domestic violence or repeated childhood abuse. The symptoms of complex PTSD cause substantial impairment in personal, family, social, occupational or other important areas of functioning and include significant and ongoing:

  • Beliefs about oneself as being diminished, defeated or worthless, accompanied by feelings of shame, guilt or failure related to the traumatic event.
  • Problems in affect regulation.
  • Difficulties in sustaining relationships and in feeling close to others.

The established code for Complex PTSD is 6B41.


Prolonged Grief Disorder

Prolonged Grief Disorder (PGD) is a condition in which, following the death of a person close to the bereaved, such as a spouse, partner, parent or child, there is a persistent and pervasive grief response. This response is characterized by longing for the deceased or a preoccupation with the deceased accompanied by intense emotional pain. Examples of this emotional pain include sadness, guilt, anger, denial, difficulty accepting death and feeling that one has lost a part of one’s self.

The grief response in cases of PGD persists for an atypically long period of time following the loss (more than 6 months at a minimum) and exceeds what is considered a normative period of grieving, taking into account the person’s cultural and religious context. The disorder causes significant impairment in the bereaved individual’s personal, family, social, occupational or other important areas of functioning.

The established code for PGD is 6B42.

How to Prepare for ICD-11 Medical Coding and Billing Changes 

Medical coding and health information management (HIM) professionals must take the time to become familiar with the new ICD-11 concepts and prepare for the transition thanks to the large number of diagnoses added to this edition, along with the new coding system. While the expanded features of ICD-11 will ultimately give medical coders and billers more advanced tools with which to do their jobs, they will need training to learn how to use them accurately.

Here are a few ways healthcare organizations can proactively support their staff:

  • Develop training plans before making the transition. You may need to reassess training processes to ensure that your coding team has the resources it needs to adapt to the ICD-11 changes.

  • Work with IT to update your systems and applications (i.e., HER, practice management, revenue cycle management software) to versions that support integration with the ICD-11 database.

  • Work with experienced coding specialists to evaluate how you can make changes to the current coding and billing practice to optimize revenue cycle management, reduce coding errors and improve patient outcomes based on the new ICD-11.

  • Assign a dedicated resource to monitor updates and communicate ICD-11 status to stakeholders. This person should stay current with ICD-11 news and announcements from the U.S. Department of Health and Human Services (HHS), the Centers for Medicare & Medicaid Services (CMS), the American Health Information Management Association (AHIMA), the American Medical Association (AMA) and other industry organizations.

ICD vs. DSM: What’s the Difference?

While the ICD and the Diagnostic and Statistical Manual of Mental Disorders (DSM) are both authoritative guidebooks for medical and mental health professionals and share some similarities, there are substantial differences between them. The primary difference is that the ICD is much broader in its scope and authorship. Here’s a breakdown:

  • While the ICD covers all parts of the body and mind, the DSM focuses solely on mental health disorders.

  • Published by the American Psychiatric Association, the DSM has a narrow scope and is focused on North America. The ICD’s authorship is global and is open to the public for submissions.

  • The ICD provides codes for each diagnosis for insurance billing, but the DSM doesn’t have its own codes. It publishes the corresponding ICD codes for each mental health diagnosis.


Will there be an ICD-12?

It’s impossible to say whether, or when, a 12th revision will be introduced. ICD-11 was built as a database and is accessible as a web platform to support the use of EHRs, a flexibility that was not possible in the previous, static platform. ICD-11 is also very expandable, which might mean than an ICD-12 wouldn’t be necessary. However, if new medical information or data analytics technologies are introduced that require a major overhaul, an ICD-12 could be revisited.

Is ICD-11 the only medical coding classification system?

No. There are currently 5 major medical coding classification systems: ICD-11 (which is intended to replace ICD-10 as the global standard for diagnostic codes), ICD-10CM, ICD-10-PCS, CPT and HCPCS Level II. If you’re interested in a career in medical billing and coding, it’s important to learn about each of them.

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