An IPPS Proposed Rule Preview – Body Mass Index (BMI)

An IPPS Proposed Rule Preview – Body Mass Index (BMI)

It’s hard to believe, but it is already June! School is out, the weather is warmer, and hopefully, you have a vacation on the schedule! It also means we have had the Inpatient Prospective Payment System (IPPS) Proposed Rule for a couple of weeks now.

Prior to the IPPS Masterclass this August, I will be doing a series of previews identifying some proposed code and DRG changes, with a focus on our current guidelines and guidance.

The first proposed invalid code for the 2027 fiscal year (FY) is Z68.1, Body mass index (BMI) 19.9 or less, adult. Codes may be proposed to be invalid for a number of reasons, with one being that there are new proposed codes that offer more specificity or further clarification. That is indeed the case here. For FY 2027, Z68.1 will become invalid and will be replaced by two new codes:

  • Z68.18        Body mass index (BMI) 18.4 or less, adult; and
  • Z68.19        Body mass index (BMI) 18.5-19.9, adult.

Code Z68.1 was considered a complication or comorbidity (CC) condition, and both new codes, Z68.18 and Z68.19, will be as well. This seems to be a very straightforward update that allows for that further specificity in the lower BMI values to be represented. It is important to remember that these are adult codes only. Our adult BMI codes are assigned for patients 20 and older. Pediatric BMI codes are to be assigned in patients ages 2-19. This is a very common audit error.

Many patients 18-19 years old have moved on from their pediatrician’s practice and are now patients of “adult” general practitioners. Regardless of where they receive care, the adult BMI codes can’t be assigned until they are 20 years old. 

As part of last year’s final rule, we got an update to our BMI coding guidelines. Please review 21.c.3 for the full guideline. While we know we only assign codes for BMI values when there is an associated, reportable diagnosis, our guideline update added the example of anorexia to the previous example of obesity. This makes the guideline inclusive of conditions representing values both high and low. It also added the guidance that the diagnosis should be documented by the patient’s provider.

This adds further clarification that while we can assign the BMI value based on documentation from other clinicians, that corresponding diagnosis must come from the provider. 

The next part of the update further instructs that “when the documentation reflects fluctuating BMI values during the current encounter for an associated reportable condition, assign a code for the most severe value.” This means the highest or lowest BMI value during the encounter will be assigned.

This is another common audit error. Many facility-specific coding rules instruct their coders to pull the BMI value from the history and physical (H&P) or the dietary evaluation for example.

While this could have been an attempt for consistency, it no longer follows the official guidelines. Make sure your coders are aware of this, and double-check your facility-specific policies to see if they need to be updated to reflect the current guidance. 

As part of your review in BMI code assignment, I would encourage you and your coding team to re-review the Coding Clinic edition from the fourth quarter of 2018 on this topic. It includes a dozen questions with answers on various BMI coding issues.

It addresses morbid obesity reported with a documented BMI less than 40, issues with the definition of reportable additional diagnoses, and reinforcing the guideline that BMI codes are not to be assigned in pregnancy. 

As a final reminder, remember that this is the proposed rule. We will see if the BMI coding changes are finalized as part of the final rule in the next couple months.

The comment period is still open, so if you wish to share your comments on this or any proposed change, you have until June 9. 

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Christine Geiger, MA, RHIA, CCS, CRC

Chris began her health information management career in 1986, working in hospitals and as a consultant. With expertise in ICD-10 coding, audits, and education, she has contributed to compliance reviews and coding programs. She holds a Master's from Washington University, a B.S. from Saint Louis University, and has taught coding at Saint Louis University. Chris is certified in HCC risk-adjusted coding and is active in health management associations.

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