Medicare Advantage plans have become popular with consumers because they combine traditional Medicare benefits with additional coverage, such as vision, dental care, and prescription drugs.

The program paid $210 billion to Medicare Advantage plans last year. Companies including UnitedHealth Group Inc., Humana Inc., and Aetna Inc. are the largest sellers of the coverage. Enrollment in Medicare Advantage has roughly doubled in the past decade, and one-third of Medicare patients are now covered by the private plans.

In 2016, Medicare Advantage plans denied 4 percent of requests to approve treatment before it was provided, known as prior authorization, and 8 percent of requests for payment after treatment, according to the report.

Only 1 percent of patients disputed the insurers' denials, but in those cases, the decisions were overturned three-quarters of the time, according to the report.

Improper denials “may contribute to physical harm for beneficiaries if they're not getting access to services that they need,” said Rosemary Rawlins, the inspector general's team leader on the report. Patients and doctors can also be harmed financially if not reimbursed for appropriate care, she said.

If plans aren't providing the care they're contracted to, it risks wasting taxpayers' money. The government “has already paid to cover beneficiaries' health care,” Rawlins said. Not every denial is an indication that patients are being blocked from needed treatment, however.

“You wouldn't expect the denial rate to be zero,” Rawlins said. “Part of managing care is denying care that's not needed.”

There's a lot of variation in how often Medicare Advantage plan denials were overturned. In 2016, seven Medicare Advantage contracts had almost all of their denials reversed on appeal — more than 98 percent. Another 69 contracts had denial rates above 90 percent. The report doesn't name specific companies or plans. Individual insurers can have more than one Medicare Advantage contract with the government.

Problems with denials of care aren't isolated to a few plans, however. The Centers for Medicare and Medicaid Services, or CMS, audits different organizations each year, “but consistently find problems related to denials of care and payment,” Rawlins said.

The CMS audits are one of many factors that affect health plans' star ratings, which are intended to help Medicare patients shop for plans based on quality. But starting in 2019, as the result of a change by CMS, the audits will no longer be a factor in the ratings, “which diminishes the usefulness of the star ratings system as a tool for beneficiaries,” the report said.

The inspector general recommended that CMS increase its oversight of Medicare Advantage plans and give patients better information about violations. The agency concurred with the findings.

A CMS spokesperson said in an email that the agency is committed to “strong oversight and enforcement of the Medicare Advantage program to ensure that plans are delivering care to Medicare beneficiaries” as required.

Read more:

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• New Medicare Advantage tool will lower prices, but also limit choice
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