ICD-11: The future of diagnosis coding

July 24, 2023 / By Karla VonEschen, MS, CPC, CPMA

It feels like the medical coding world is still getting used to many aspects of ICD-10-CM, so the idea that ICD-11 is just around the corner seems wild. However, the new coding system is not too far off in the future, so we must consider the changes and how it could impact coding and revenue. In my opinion, the transition from ICD-9-CM to ICD-10-CM was more painful than the change from ICD-10-CM to ICD-11 will be. There are intricacies in ICD-11 that coders need to get used to, but it shouldn’t feel as drastic as when we transitioned to ICD-10-CM. 

When comparing the two coding systems, ICD-11 has several advantages, including creating new diagnoses, refining diagnostic criteria for existing diagnoses and adding dimensionality to some codes. Here are some other benefits of ICD-11: 

  • Updated coding for HIV, including subcategories and removal of outdated information 
  • A new supplementary section for functional assessment 
  • Inclusion of codes for rare diseases 
  • Flexibility and accuracy allow health information professionals to better track population health, patient safety and patient outcomes 
  • Expanding codes to include new terms, concepts and synonyms 

Let’s consider the following example showing how Type 2 diabetes mellitus (DM) with ketoacidosis without coma is coded in ICD-10-CM and ICD-11.   


E11.10 Type 2 diabetes mellitus with ketoacidosis without coma  5A22.0/5A11 Diabetic ketoacidosis without coma, type 2 diabetes mellitus 

The current ICD-10-CM coding system combines the type of diabetes with ketoacidosis and without coma in one code. In ICD-11, coders use a stem code to identify the main health issue and a post-coordination code to link core diagnostic concepts or add additional clinical information to the primary stem code. Diabetic ketoacidosis without coma is coded with 5A22.0, the stem code. The type of diabetes is coded with 5A11, the post-coordination code.  

The two codes together are referred to as a “cluster code.” Once the code for diabetic ketoacidosis without coma is chosen in the WHO ICD-11 Coding Tool, the coder is instructed to select a post-coordination code for the type of diabetes. Post-coordination is used to further define a health condition by applying one or more additional codes. When a stem and post-coordination code is used, the coding concept includes a slash (/) between the two codes.   

It’s difficult to determine how the United States may modify ICD-11, and no date has been identified for implementing the new coding system. This shouldn’t deter organizations from getting acquainted with the new system and, at a minimum, encourage coders to start learning about ICD-11. Now is a great time to identify your organization’s top diagnosis bills and see how those may change based on the World Health Organization (WHO) ICD-11 tool. A clinical documentation review can be performed to establish where documentation is lacking and what type of education may be needed for clinical staff.  Incomplete or missing documentation will have the same impact on ICD-11 as on ICD-10-CM. There is a domino effect when physician documentation is deficient: consider coding, reimbursement, organizational data, continuity of care for patients and potential backlog for denied services that need to be reviewed.   

I firmly believe that taking small steps now will lead to a smoother transition once an implementation date is set. It’s easy to put off information gathering, especially when the implementation of ICD-10 took so long and included multiple last minute delays. Once an implementation date is set, health care organizations can begin working with software vendors, create a formal education process for coders and clinical staff, update internal policies and procedures with information for the new coding system and ensure internal applications will accommodate ICD-11 while maintaining the previous ICD-10-CM coding system. 

Karla VonEschen is a coding analyst at 3M Health Information Systems.