Q&A: New ‘Other obesity’ codes

CDI Strategies - Volume 18, Issue 49

Q: As you can imagine, the coding and CDI world is abuzz with all the recent guidelines and code changes for fiscal year 2025 ICD-10-CM. For us specifically, the new obesity codes. The new codes are described as classifications for E66.8, Other obesity. JustCoding explains: "Subcategory E66.8 (Other obesity) was expanded to include new codes E66.811-E66.813 (Obesity classes 1-3). Obesity classes are based on [body mass index] BMI.”

This would imply it is a separate type of obesity from E66.01, Morbid obesity. However, we are now consistently seeing these codes get combined (e.g. E66.813, E66.01, Z68.41). Often when this combination is selected for “visit diagnoses,” coding is updating the claim to just E66.813, Z68.41. Additionally, we are now also seeing an option within our EHR for "Obesity, Class II, BMI 35-39.9 due to excessive calories (E66.01)".

Should the new codes E66.811-E66.813 be used to describe “Other obesity,” not classified as E66.0, Obesity due to excess calories, E66.1, Drug-induced obesity, or E66.9, Obesity, unspecified?

A: I had the same issue your team has with the addition of these new codes, since Class 3 is sometimes categorized as “severe” by the Centers for Disease Control and Prevention (CDC). But I think the key is that it doesn’t say always. I think the best way to approach this is to use the most specific code based off the documentation, since the code description does not include the BMI range that is traditionally associated with the classes. Thankfully, the Coding Clinic, fourth quarter 2024, did include the BMI ranges as a source authority. Previously, I just cited what was on the CDC site when reviewing. 

For what it's worth, since there is more to diagnosing obesity than just BMI, I think this change was a way to account for providers using generally acceptable clinical terms to utilize the classes, which was always missing from the ICD-10-CM code set.  

To answer your first question, E66.811-E66.813 should only be used if the specific class is documented. You will notice in the ICD-10-CM code set that the BMIs are not part of the code description, nor are they in the inclusion terminology. 

Q: Can/should the new codes be used in conjunction with E66.01, Morbid obesity due to excess calories? Guidelines indicate the descriptor of “severe” would allow assignment of E66.01, Morbid obesity. Similarly, we have been using the descriptor of "class 3 obesity" in the same manner. With the new codes, should the descriptor of “class 3” still be used to allow for code assignment of morbid obesity? Alternatively, should the descriptor of "class 3" be required to code morbid obesity?

A: As stated above, even though there is not an “Excludes1” note under E66.01, the perceived intention of adding specific codes for classes was to bolster specificity and not promote excessive use of E66.9, Obesity, unspecified. If the documentation identifies a class this would likely be considered more specific than E66.01. My reasoning for this is that the addition would not be necessary if morbid obesity was sufficient. Some providers will use morbid as a descriptor even for patients with BMIs less than 40, due to having at least two weight-related issues (e.g., sleep apnea, hypercholesterolemia, etc.).

Q: What is the correct way to code the following: "Class 3 severe obesity due to excess calories without serious comorbidity with BMI of 40.0 to 44.9 in adult"?

A: Based solely on this statement, to take advantage of the specificity it would seem appropriate to report E66.813, Z68.41 unless further clarifications are made by the AHA’s Coding Clinic in future releases

Q: What is the correct way to code the following: "Obesity, Class II, BMI 35-39.9 due to excessive calories"? 

A: Based solely on this statement, E66.812, Z68.3- (5th depending on BMI).

Unfortunately, when these codes were added, they did not add an “Excludes1” note which would typically be the convention the coding classification would refer to when a more specific option should be used.  The fourth quarter Coding Clinic tried to cover the ambiguity by saying, "It is based on the documentation." 

I am optimistic that a clarification will be released in the upcoming Coding Clinic for this issue, since it is quite controversial and confusing as to what it appropriates. Adding these codes under the "Other” category seems to imply it is not due to excess calories, when probably more times than not classes 1-3 are due to excess calories, but I suppose they were thinking that, on the off chance it wasn't, it was following the coding convention of "Other."

Editor’s note: Shannon McCall, RHIA, CCS, CCS-P, CPC, CEMC, CRC, CCDS, CCDS-O, director of HIM and coding at HCPro, answered this question. Contact her at shannon.mccall@hcpro.com