OIG Identifies $462 Million in Potential Medicare Advantage Overpayments for Acute Stroke Diagnoses

The Office of Inspector General (OIG) recently released a report estimating that CMS may have overpaid Medicare Advantage Organizations approximately $462 million in 2021 based on unsupported acute stroke diagnoses.

For those working in Medicare Advantage risk adjustment, the findings themselves should not come as a surprise. Stroke diagnoses have been a recurring area of concern in OIG audits for years, with many reviews identifying situations in which a beneficiary had a history of stroke but the condition was reported as an active acute event for risk adjustment purposes.

What makes this report significant is that the OIG expanded its review beyond individual organizations and evaluated the issue across the broader Medicare Advantage landscape.

According to the report, approximately 25.5 million beneficiaries were enrolled in Medicare Advantage during the period reviewed. Of those, roughly 774,000 members had a reported stroke diagnosis, representing a prevalence rate of approximately 3%. The OIG identified more than 240,000 beneficiaries whose stroke diagnoses were reported under circumstances it considered high risk, such as physician office encounters without evidence of an acute stroke hospitalization or outpatient hospital visit during the same service year.

To evaluate the issue, the OIG reviewed a sample of 97 beneficiaries and found that none of the acute stroke diagnoses submitted by Medicare Advantage organizations were supported by the associated medical records. Based on those findings, the agency estimated that CMS may have overpaid health plans approximately $462 million for this diagnosis category alone.

These findings are consistent with previous OIG audits. Since 2022, the OIG has completed numerous Medicare Advantage reviews involving stroke diagnoses and has repeatedly identified the same pattern: historical stroke conditions being reported as active acute stroke events. The consistency of these findings suggests that stroke remains one of the more vulnerable diagnosis categories from both a coding accuracy and compliance perspective.

The broader implication extends beyond stroke. The OIG continues to demonstrate how data analytics can be used to identify diagnosis patterns that warrant additional scrutiny. In this case, the agency focused on acute stroke diagnoses reported without corresponding hospital-based treatment records. Similar analytical approaches can be applied across many other high-risk conditions and diagnosis categories.

For Medicare Advantage organizations, these reports provide valuable insight into where regulators are focusing their attention. They serve as an early warning regarding diagnoses, documentation practices, and coding patterns that may present elevated compliance risk and future audit exposure.

How Rebellis Can Help

The OIG's findings reinforce the importance of proactive risk adjustment oversight. Rebellis partners with Medicare Advantage organizations to assess compliance risk, evaluate diagnosis reporting accuracy, and strengthen audit readiness through targeted coding reviews, diagnosis validation audits, mock RADV assessments, provider education, and operational process evaluations.

As regulators increasingly leverage data analytics to identify high-risk diagnoses and coding patterns, organizations should ensure they have the governance, monitoring, and validation processes necessary to detect issues internally before they become audit findings. Rebellis helps plans identify potential vulnerabilities, quantify exposure, and implement practical solutions that support accurate risk adjustment reporting and regulatory compliance.

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