UnitedHealth Group Inc. used “aggressive strategies” to maximize diagnoses and boost payments for patients on private Medicare health plans, a new Senate report found, adding to pressure on the largest US health insurer.

The health-care conglomerate has a “robust” workforce — augmented by artificial intelligence — to capture diagnoses that drive payments in the Medicare Advantage program, the report from the Senate Judiciary majority staff said. Advantage plans have been dogged by allegations from watchdogs and whistleblowers that they exaggerated how sick their members are to inflate their payments from the government.

UnitedHealth, the largest seller of private Medicare Advantage plans, said it disagreed with the committee’s characterization of its practices.

“Our programs comply with applicable CMS requirements and have, through government audits, demonstrated sustained adherence to regulatory standards,” the company said in a statement.

UnitedHealth shares fell as much as 2.9% in New York. The company, which is set to report earnings later this month, separately reaffirmed its 2025 forecast in a filing Monday.

More pressure

The report adds to growing pressure on companies selling private versions of Medicare health plans. The Medicare Advantage program paid nearly half a trillion dollars to private insurers in 2024 to cover about half of people on Medicare. That business has driven most of the growth for US health insurers in the last decade.

The report found that risk adjustment, the process of identifying patient diagnoses, “has become a business in itself — by no means should this be the case.” Medicare Advantage plans should be paid based on the needs of their patients, “not their knowledge of coding rules and their ability to find new ways to expand inclusion criteria for diagnoses.”

Mehmet Oz, the Trump administration’s leader of Medicare and Medicaid, promised a crackdown on insurers’ efforts to amplify diagnoses that lead to higher payments, a practice he’s called “cheating.”

Insurance companies say they’re paid appropriately for the risk they take on and reject accusations that they’ve inflated payments in Medicare Advantage. In the past few years, the business has become more challenging for health insurers, as medical costs rise faster than expected and the federal government has pulled pack on extra payments for some diagnoses.

Grassley wrote to UnitedHealth last February asking about aspects of the company’s Medicare business and how it submits information to the government on patient illnesses for reimbursement. The letter cited reporting in the Wall Street Journal that suggested the company generated billions in payments through questionable diagnoses. The insurer has defended its practices.

The Judiciary staff report was based on more than 50,000 pages of documents the company sent to Grassley’s office. The findings were first reported by the Wall Street Journal.

UnitedHealth is also facing civil and criminal probes into aspects of its business including Medicare billing. The company has said it’s cooperating with those investigations and has “full confidence” in its practices.

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