CMS Claims Risk Adjustment Overpayments Commonly Include 10 Specific Diseases

by  Aimee L. Wilcox, CPMA, CCS-P, CST, MA, MT
May 24th, 2022

Over the past few years, we have seen several Medicare Advantage (MA) plans audited by the Office of Inspector General (OIG) that have provided significant feedback for HCC or risk adjustment coders and Medicare Advantage Organizations (MAOs). Once the OIG has completed their audit and published their findings, the report is made public for anyone to review.

In May 2021, the Department of Health and Human Services (HHS) OIG published a report titled, “Medicare Advantage Compliance Audit of Specific Diagnosis Codes that Anthem Community Insurance Company, INC (Contract H3655) Submitted to CMS.” This audit included claims for MA enrollees from 2015-2016. Please note that ICD-10-CM was implemented on October 1, 2015, so this particular audit includes a review of both ICD-9-CM and ICD-10-CM diagnosis codes and coding guidelines.

An overview of the OIG’s findings clearly shows a disagreement between the OIG and Anthem regarding the methodologies used for the review, disagreements related to specific chart reviews, and a claimed misunderstanding of legal and regulatory requirements. The OIGs report identified seven (7) high-risk disease groups that are commonly misreported due to a lack of supporting documentation in the medical record and indicates as part of their strategy, that they focused on these specific diagnoses, which include: 

Best coding practices would warrant the inclusion or mention of a recent inpatient hospital encounter supporting the diagnosis and treatment for the acute conditions. For example, ICD-10-CM category I21.- includes a related ICD-10-CM coding guideline that states, 

“For encounters occurring while the myocardial infarction is equal to, or less than, four weeks old, including transfers to another acute setting or a post-acute setting, and the myocardial infarction meets the definition for “other diagnoses” (see Section III, Reporting Additional Diagnoses), codes from category I21 may continue to be reported. For encounters after the 4-week timeframe and the patient is still receiving care related to the myocardial infarction, the appropriate aftercare code should be assigned, rather than a code from category I21. For old or healed myocardial infarctions not requiring further care, code I25.2, Old myocardial infarction, may be assigned.”

While the OIG’s review impresses upon us the importance of identifying documents that provide additional supporting evidence, such as a recent MRI study to support an acute stroke, or a history and physical or discharge summary within the last 60 days to support an acute heart attack, it also begs the question of how much evidence is enough to support these high-risk diagnoses? 


While the OIG’s review indicated that the patient was not on a prescribed anticoagulant, a closer review of the record is always warranted, as not every patient is eligible for or able to take anticoagulant therapy and may, instead, require a vascular filter (e.g., IVC filter) to prevent a life-threatening pulmonary embolism. The patient’s documented history and not just the medication list will be an important factor in providing enough supporting evidence for these high-risk diagnoses. 

Vascular Claudication

TheOIG noted this high-riskHCC condition is commonly misreported from a problem list or past medical history when it should be supported by a medical record that identifies the coAdminndition as actively being treated. 

Major Depressive Disorder 

Coders and auditors must clearly understand the coding guidelines specific to reporting the various types of depression and major depressive disorders. While the new ICD-10-CM code F32.A for “depression, unspecified” was added in October 2021, it only risk-adjusts to RxHCC and not to CMS-HCC or HHS-HCC. On the other hand, major depressive disorder (MDD) represented by ICD-10-CM codes F32.0-F32.5, do risk adjust to RX, CMS, and HHS version and may be represented as mild, moderate, or severe and any supporting documentation, including prescription medications used to treat the condition are considered adequate to support reporting as an HCC condition.

Potentially Mis-keyed Diagnosis Codes 

The OIG report references a tool they developed to identify commonly mis-keyed ICD-9-CM diagnosis codes that correlate to high-risk HCC codes. Not available for ICD-10-CM, but applicable for the audit year January 2015-September 2015, it was used to identify any of the 832 potentially mis-keyed diagnosis codes. Anthem argued their inability to replicate the OIG’s methodology for this particular finding, indicating the algorithm used to identify additional issues beyond the audited population was never provided to them.

While these reports often provide great insights into the approach and methodologies used by the OIG in these audits, they also contain vital information on how MAOs push back by deploying their own audits of the data to identify and counter potentially misleading or inaccurate claims made by the OIG auditors. Many lessons can be learned by reviewing these types of audits, and facilitating implementation of compliance policies to avoid similar errors.


Disclaimer: The above article is the opinion of the author(s) and should not be interpreted by providers/payers as official guidance. For any questions about the content of this article, please contact the author(s).

About the Author: Aimee L. Wilcox is a medical coding, billing, and auditing consultant, author, and educator with more than 30 years of clinical and administrative experience in healthcare, coding, billing, and auditing. Medicine, including coding and billing, is a constantly changing field full of challenges and learning and she loves both. Aimee believes there are talented medical professionals who, with proper training and excellent information, can continue to practice the art of healing while feeling secure in their billing and reimbursement for such care.

CMS Claims Risk Adjustment Overpayments Commonly Include 10 Specific Diseases. (2022, May 24). Find-A-Code Articles. Retrieved from

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