Special Bulletin: OIG Looks at Medicare Advantage Risk Score Audits

MAOs use chart reviews to increase risk-adjusted payments is seen as inappropriate by the OIG. 

The U.S. Department of Health and Human Services (HHS) Office of Inspector General (OIG) released a study that should cause a chill to run down the spines of hospital and Medicare Advantage plan leaders alike. The study was published on Dec. 13, 2019.

First, you have to understand how risk scoring works, and why hospitals and Medicare Advantage plans could even collude to increase reimbursement for both entities.

Medicare Advantage plans are reimbursed via a base “per patient day” (PPD) amount, adjusted for the individual weighted score computed using Hierarchical Condition Codes (HCCs). The Centers for Medicare & Medicaid Services (CMS) takes all of the diagnosis codes submitted on paid claims and uses them to adjust how much they think a patient with those codes should cost on a daily basis.

Hospitals are paid based on the diagnosis-related group (DRG) assigned, based on the same diagnosis codes.

Here is where it gets crazy. Since most contracts between hospitals and Medicare Advantage plans are based on Medicare DRGs, both the hospital and the Medicare Advantage plan increase reimbursement by coding (or maybe over-coding) certain diagnosis codes.

Let’s look at why the OIG performed this audit, in their own words:

“We undertook this study because of concerns that Medicare Advantage organizations (MAOs) may use chart reviews to increase risk-adjusted payments inappropriately. Unsupported risk-adjusted payments are a major driver of improper payments in the Medicare Advantage (MA) program, which provided coverage to 20 million beneficiaries in 2018 at a cost of $210 billion.”

What is the OIG talking about, with chart reviews to increase reimbursement to the Medicare Advantage plan? Most plans have teams of “risk adjustment auditors” that review claims using “suspect” data analysis. The plans look at billings from the last Medicare Advantage plan for patients, medications the patient may be taking, and computer modeling to see if the patient is really sicker than the billed claims data shows. If they confirm that the patients may have other diagnoses not listed on the billed data, they notify the providers, asking them to rebill claims with the new diagnosis found during the “audit.” That’s good news for the plan, and good news for the provider, in most cases. It is bad news for Medicare.

This is how the OIG described its audit process:

“We analyzed 2016 MA encounter data to determine the 2017 financial impact of diagnoses reported only on chart reviews, and not on any service record in the encounter data that year. We also analyzed CMS’s responses to a structured questionnaire to identify action taken by CMS to review the impact of chart reviews on MA payments.”

What did the OIG find?
“Our findings highlight potential issues about the extent to which chart reviews are leveraged by MAOs (Medicare Advantage Organizations) and overseen by CMS. Based on our analysis of MA encounter data, we found that MAOs almost always used chart reviews as a tool to add, rather than to delete, diagnoses – over 99 percent of chart reviews in our review added diagnoses. In addition, diagnoses that MAOs reported only on chart reviews (and not on any service records) resulted in an estimated $6.7 billion in risk-adjusted payments for 2017. CMS based an estimated $2.7 billion in risk-adjusted payments on chart review diagnoses that MAOs did not link to a specific service provided to the beneficiary – much less a face-to-face visit.”

What should hospitals do?
We think that hospitals should perform regular coding audits and compare findings between Medicare Advantage, standard Medicare, and managed care payers. We specifically think that providers need to request the results of coding audits performed by Medicare Advantage plans and to notify the compliance officer of the hospital of any changes made by the plan. Providers should also make sure that contracts with MA plans require the plan to disclose the results of any claim audits performed.

Read the OIG report: https://oig.hhs.gov/oei/reports/oei-03-17-00470.asp

Facebook
Twitter
LinkedIn

Timothy Powell, CPA, CHCP

Timothy Powell is a nationally recognized expert on regulatory matters, including the False Claims Act, Zone Program Integrity Contractor (ZPIC) audits, and U.S. Department of Health and Human Services (HHS) Office of Inspector General (OIG) compliance. He is a member of the RACmonitor editorial board and a national correspondent for Monitor Mondays.

Related Stories

Leave a Reply

Please log in to your account to comment on this article.

Featured Webcasts

Mastering Principal Diagnosis: Coding Precision, Medical Necessity, and Quality Impact

Mastering Principal Diagnosis: Coding Precision, Medical Necessity, and Quality Impact

Accurately determining the principal diagnosis is critical for compliant billing, appropriate reimbursement, and valid quality reporting — yet it remains one of the most subjective and error-prone areas in inpatient coding. In this expert-led session, Cheryl Ericson, RN, MS, CCDS, CDIP, demystifies the complexities of principal diagnosis assignment, bridging the gap between coding rules and clinical reality. Learn how to strengthen your organization’s coding accuracy, reduce denials, and ensure your documentation supports true medical necessity.

December 3, 2025

Proactive Denial Management: Data-Driven Strategies to Prevent Revenue Loss

Denials continue to delay reimbursement, increase administrative burden, and threaten financial stability across healthcare organizations. This essential webcast tackles the root causes—rising payer scrutiny, fragmented workflows, inconsistent documentation, and underused analytics—and offers proven, data-driven strategies to prevent and overturn denials. Attendees will gain practical tools to strengthen documentation and coding accuracy, engage clinicians effectively, and leverage predictive analytics and AI to identify risks before they impact revenue. Through real-world case examples and actionable guidance, this session empowers coding, CDI, and revenue cycle professionals to shift from reactive appeals to proactive denial prevention and revenue protection.

November 25, 2025
Sepsis: Bridging the Clinical Documentation and Coding Gap to Reduce Denials

Sepsis: Bridging the Clinical Documentation and Coding Gap to Reduce Denials

Sepsis remains one of the most frequently denied and contested diagnoses, creating costly revenue loss and compliance risks. In this webcast, Angela Comfort, DBA, MBA, RHIA, CDIP, CCS, CCS-P, provides practical, real-world strategies to align documentation with coding guidelines, reconcile Sepsis-2 and Sepsis-3 definitions, and apply compliant queries. You’ll learn how to identify and address documentation gaps, strengthen provider engagement, and defend diagnoses against payer scrutiny—equipping you to protect reimbursement, improve SOI/ROM capture, and reduce audit vulnerability in this high-risk area.

September 24, 2025

Trending News

Featured Webcasts

Surviving Federal Audits for Inpatient Rehab Facility Services

Surviving Federal Audits for Inpatient Rehab Facility Services

Federal auditors are zeroing in on Inpatient Rehabilitation Facility (IRF) and hospital rehab unit services, with OIG and CERT audits leading to millions in penalties—often due to documentation and administrative errors, not quality of care. Join compliance expert Michael Calahan, PA, MBA, to learn the five clinical “pillars” of IRF-PPS admissions, key documentation requirements, and real-life case lessons to help protect your revenue.

November 13, 2025
E/M Services Under Intensive Federal Scrutiny: Navigating Split/Shared, Incident-to & Critical Care Compliance in 2025-2026

E/M Services Under Intensive Federal Scrutiny: Navigating Split/Shared, Incident-to & Critical Care Compliance in 2025-2026

During this essential RACmonitor webcast Michael Calahan, PA, MBA Certified Compliance Officer, will clarify the rules, dispel common misconceptions, and equip you with practical strategies to code, document, and bill high-risk split/shared, incident-to & critical care E/M services with confidence. Don’t let audit risks or revenue losses catch your organization off guard — learn exactly what federal auditors are looking for and how to ensure your documentation and reporting stand up to scrutiny.

August 26, 2025

Trending News

Happy National Doctor’s Day! Learn how to get a complimentary webcast on ‘Decoding Social Admissions’ as a token of our heartfelt appreciation! Click here to learn more →

CYBER WEEK IS HERE! Don’t miss your chance to get 20% off now until Dec. 1 with code CYBER25

CYBER WEEK IS HERE! Don’t miss your chance to get 20% off now until Dec. 2 with code CYBER24