ICD-11 Insights and Updates

Timing/Dates
The World Health Organization (WHO) began developing the International Classification of Disease, Eleventh version (ICD-11) in 2007 and first released a preliminary version for evaluation and testing in 2016. Which was ironically just one year after the U.S. finally adopted a clinical modification of the WHO’s ICD-10 (i.e. ICD-10-CM).

In May 2019, the World Health Assembly adopted ICD-11 for implementation in 2022.

On February 11, 2022, the World Health Organization (WHO) released ICD-11 2022. This is the official version of the eleventh revision of the International Classification of Diseases that WHO member countries are implementing worldwide. At this point, the WHO has moved on to the 11th version of ICD and is no longer supporting ICD-10 (which was first released in 1992). [The implication here is that our ICD-10-CM, though we just finally implemented it in the US in 2015, is based on an old, essentially obsolete system that WHO no longer supports.) Though to many it feels like we just implemented ICD-10-CM like yesterday, in fact if we start planning the implementation of ICD-11 now – by the time we implement a version of ICD-11, it will be more than 10 years since we implemented ICD-10-CM.

ICD-11 Content
ICD-11 is entirely digital with integrated application program interface (API) tools to facilitate implementation. In addition, according to the WHO, this eleventh version of ICD was compiled and updated with input from over 90 countries, which represents unprecedented involvement of health-care providers. Thus, ICD-11 is thoroughly and scientifically updated and designed for use in a digital world.

The 11th version of ICD is very different from the 9th and 10th versions that the U.S. modified to create the ICD-9-CM and ICD-10-CM code sets respectively. New features of ICD-11 include:

• An entirely new architecture that includes the Foundation Component, an underlying knowledge base from which a subset (or “linearization”) is defined to create a tabular list and alphabetic index
• Over 80,000 entities that point to approximately 17,000 codes in 26 chapters (compared to approximately 14,000 codes in 21 chapters in ICD-10)
• Alphanumeric codes ranging from 1A00 to ZZ92.ZZ (minimum of 4, maximum of 7 characters)
• New chapters covering sleep-wake disorders, traditional medicine and sexual health
• Up to date scientific knowledge, for example newly discovered microbes (e.g. COVID-19) and gaming disorders (added to the addictive disorders chapter)
• A new coding approach: “cluster” coding, which provides a mechanism to use more than one code, in a cluster, to fully represent a concept
• Machine computable design, including a unique resource identifier (URI) for each entity and an application program interface

New concepts in ICD-11 (not in ICD-10):

• Stem codes (codes that can be used alone or in combination with another code)
• Extension codes (cannot be used alone; designed to standardize the way additional details are added to a stem code)
• Post-coordination (provides a way to cluster more than one code together, e.g. a stem code with an extension code, to capture the desired level of detail)
• Cluster coding (involves the process of post-coordination of two or more stem codes or a stem code with one or more extension code using an ampersand & between the codes)

Implementation Date
So when will the U.S. replace ICD-10-CM and begin using a version of ICD-11 for reporting on health care claims? Well, we don’t know yet. But this release of the official ICD-11 is sure to spur activity in this respect.

In September 2021, the NCVHS issued recommendations to the Secretary of HHS advising on a research agenda to evaluate the use of ICD-11 in the U.S.
Three Key factors that will impact ICD-11 implementation timeline (decision points to watch for that signal movement in this direction):

• Regulatory vs. sub-regulatory process (NCVHS recommended that HHS use a sub-regulatory process to move from ICD-10-CM to ICD-11, i.e. make a version update as they do with all the other named HIPAA standards. If HHS accepts this recommendation, that will simplify the
  process and shorten the timeline)
• Changing the diagnosis code set alone vs. both diagnosis and procedure code set update (NCVHS also recommended that HHS clarify that ICD-10-PCS will not be updated with the transition of ICD-10-CM to ICD-11. Uncoupling the two code sets would further simplify and speed up the move to ICD-11.)
• Adopting a linearization of ICD-11 vs. creating a clinical modification (The US could define a subset of ICD-11 to use, rather than taking years to create an ICD-11-CM)

Results of Early Research on ICD-11
Three key studies have been published (2 by the NLM and one was a volunteer effort I did with a couple colleagues, all three publications are referenced below) Summary of research conclusions to date:

• 35% of the most commonly used ICD-10-CM codes can be fully represented by ICD-11 (using extension codes and post-coordination)
• By adding just 8 extension codes, ICD-11 can represent 60% of the most common ICD-10-CM codes (which is remarkable. When we switched from ICD-9-CM to ICD-10-CM, only 24% of ICD-9-CM codes were matched with an ICD-10-CM code)
• For patient safety, i.e. representing pressure ulcers: ICD-11 exceeds ICD-10-CM capabilities (using extension codes and post-coordination)
• For quality measures, i.e. representing Ischemic stroke, hypertension, and diabetes value sets found in electronic clinical quality measures (eCQMs): ICD-11 fully represents the disease concepts (using extension codes and post-coordination)
• ICD-11 has the potential to improve data capture for broader uses and could replace ICD-10-CM