New 2019 regulations for BMI coding

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Q: Can an ICD-10-CM body mass index (BMI) code be used as a stand-alone code? If not, what does the documentation need to include to justify the use of a BMI code?

A: The 2019 ICD-10-CM Official Guidelines state that you cannot use a BMI code alone (these are found in ICD-10-CM code category Z68.-). BMI codes should only be assigned when the associated diagnosis (such as overweight or obesity) meets the definition of a reportable diagnosis.

Keep in mind that that BMI codes were never intended to be used as standalone codes; they were always meant to be accompanied by a corresponding diagnosis code.  In previous years, the guidelines read, “As with all other secondary diagnosis codes, the BMI codes should only be assigned when they meet the definition of a reportable diagnosis.” However, there was a long-standing issue of Coding Clinic published in 2011 that stated:

“Individuals who are overweight, obese or morbidly obese are at an increased risk for certain medical conditions when compared to persons of normal weight. Therefore, these conditions are always clinically significant and reportable when documented by the provider. In addition, the body mass index (BMI) code meets the requirement for clinical significance when obesity is documented.”

This 2011 direction appears to no longer be valid. The Coding Clinic published in the fourth quarter of 2018 specifically states that the provider must provide documentation of a clinical condition such as obesity or overweight to justify the reporting of a code for BMI.

So this begs the question of what diagnoses, such as sleep apnea, diabetes, or hypertension, could make the use of a BMI code relevant. The same Coding Clinic article does not identify the conditions that can be considered associated with a BMI. So my best advice to show that BMI is clinically relevant is to ensure that the documentation clearly links the condition to BMI. 

For patients with provider documentation identifying “morbid” obesity, the code E66.01 (morbid [severe] obesity due to excess calories) can be assigned even if the BMI is not greater than 40, per the Coding Clinic.  This guidance is important since there are some situations where a patient can have severe or morbid obesity with a BMI of 35-39.9 due to co-existing comorbid conditions.  

As noted in the 2019 ICD-10-CM Official Guidelines, Section I.A.19, “The assignment of a diagnosis code is based on the provider’s diagnostic statement that the condition exists. The provider’s statement that the patient has a particular condition is sufficient. Code assignment is not based on clinical criteria used by the provider to establish the diagnosis.” 

Renee Dowling is a billing and coding consultant with VEI Consulting in Indianapolis, Ind. Send your billing and coding questions to medec@ubm.com.