A Reframing of Obesity on the Horizon

This a heads-up on a definitional change coming our way. There will be the launching of a new framework for obesity in mid-January, per a commission of academic clinicians, scientists, public health experts, patient representatives, and the World Health Organization (WHO).

The consensus statement will be published in The Lancet Diabetes and Endocrinology, and more than 75 medical societies and other organizations have endorsed it.

The concept is that individuals who have excess adiposity, or fat, in their body can either be at risk of or be actively experiencing adverse effects and bodily harm from it. The state of having excess adiposity with consequent tissue and organ abnormalities is being reframed as a disease state called “clinical obesity.”

Currently, we assess a patient’s body mass index (BMI) to diagnose obesity. BMI has limitations. The formula used to calculate BMI uses a patient’s weight, but there is no consideration for whether the weight is due to lean body mass or fat mass. A very muscular person may have a high BMI, but low fat mass. BMI doesn’t note where fat has accumulated. Central abdominal fat due to visceral fat offers a higher risk of conditions like heart disease and diabetes.

BMI is useful as a screening tool, but once obesity has been identified, whether it is clinical or nonclinical needs to be established. This is even embedded in how we currently stratify obesity. The condition that used to be called “morbid obesity” has been rebranded as Class 3 obesity, or severe obesity. It is characterized by a BMI ≥ 40 or a BMI ≥ 35 with obesity-related health conditions. Examples of these conditions are hypertension, Type 2 diabetes, and atherosclerotic heart disease.

Just like the evolution of sepsis caused all sorts of coding headaches, I predict that the change in obesity nomenclature may cause coding troubles in ICD-10-CM. The current indexing has a code, E66.2, for morbid obesity with alveolar hypoventilation, also known as obesity hypoventilation syndrome. E66.2 is the only comorbid condition or complication (CC) in the subcategory. There is also a code for morbid obesity due to excess calories, E66.01, but I wonder how often clinicians use this precise verbiage. Fortunately, the indexing of the phrase “morbid obesity” allows assignment of E66.01. On Oct. 1, 2024, the code set expanded to include the classes of obesity (Classes 1-3). Class 3 obesity is coded with E66.813. If a provider says, “Morbid obesity, Class 3,” how is that handled?

Is the verbiage, “clinical obesity” going to be assigned E66.89, Other obesity not elsewhere classified, or E66.9, Obesity, unspecified? Are providers going to diagnose specific classes of obesity as clinical obesity, if there are obesity-related conditions?

Coders are permitted to pick up the Z code indicating the BMI if a practitioner has made a nutritional diagnosis, even if the BMI has been recorded by a nurse or dietitian. If the clinician only explicitly diagnoses “obesity,” but the BMI is 42, should the clinical documentation integrity (CDI) specialist or coder pick up the obesity without the more specific classification? BMI of 40 or greater also affords the Complication or Comorbidity (CC) designation.

For Diagnosis-Related Group (DRG) and reimbursement purposes, the unspecified code for obesity with the BMI of ≥ 40 to 44.9 giving the CC of Z68.41 would be adequate. Codes are not only for reimbursement, but also for epidemiological, statistical, and public policy purposes.

Now that we have some very effective treatments in the glucagon-like peptide-1 receptor agonist drugs, we want to be sure that patients at highest risk get preferential access. But are we really going to query for higher specificity?

It will be interesting to see if WHO is going to adapt ICD-11, according to this new disease definition, since they were at the table creating the framework.

Whether it will trickle down and over to ICD-10-CM is yet to be seen.

Programming note:

Listen to Dr. Erica Remer as she cohosts Talk Ten Tuesday today with Chuck Buck at 10 am Eastern.