The fate of Medicare plans offered by private insurance companies is in question as the federal government seeks to cover costs of the health care overhaul by reducing payments for those plans.

The changes to the plans, called Medicare Advantage, would affect about 14 percent of Virginians currently enrolled in Medicare.

"I'm not sure that anybody truly understands what has been passed nor do they understand how it will affect Medicare Advantage," said Shannon Abell, director of senior services at the LOA Area Agency on Aging. "I've heard a lot of talk about it, but no insurance company, as far as I know, has come out in writing and said one way or another."

While the rate cuts won't take effect until next year, the popularity of the plans has grown recently. And Medicare recipients have until today to switch their current plans for 2010.

Insurers are also emphasizing that the health care overhaul will lead to changes in Medicare, but those will be phased in over many years.

"The bottom line is, right now, there are no changes," said Debora Spano, UnitedHealthcare spokeswoman.

Additionally, supplement policies owned by many people who do not select a Medicare Advantage plan, are largely unaffected by the legislation, she said.

Medicare Advantage plans offer benefits equal to or greater than guaranteed benefits under traditional Medicare and are reimbursed at a fixed rate regardless of the actual cost of providing service to an individual.

Medicare currently pays these private plans on average 14 percent more than the average monthly cost for beneficiaries in traditional Medicare. For a typical couple in traditional Medicare, that would have equated to nearly $90 in additional Medicare premiums in 2010, according to the Centers for Medicare & Medicaid Services.

The Obama administration argued, and others such as AARP agreed, that the overpayments were driving up the overall costs of Medicare. The Congressional Budget Office concluded that the overhaul will reduce annual growth in Medicare expenditures by 1.4 percentage points per year and extend the program's solvency by at least nine years.

Ultimately it will be up to the private insurers who issue the plans to decide if it is still economically feasible to continue with Medicare Advantage.

"Some may reduce some benefits like gym memberships or eyeglasses," Bill Kallio, president of AARP Virginia, said in an e-mail. "Some may decide they can't make enough profit. In no circumstances can these plans offer less than what is guaranteed under traditional Medicare."

Insurance companies are still working through the specifics of the bill.

"There are still a lot of details that need clarifying," said Scott Golden, spokesman for Anthem Blue Cross Blue Shield of Virginia. "There is a lot of gray area."

Insurers are also waiting on more information from the government about the implementation of the new law, Golden said.

Even as insurance companies grapple with how the overhaul will change their business practices, Medicare Advantage plans are advertising enrollment through today. After today Medicare recipients will be locked into their current plan for the year.

While the vast majority of the 1.1 million Medicare recipients in Virginia don't select the private medicare plans, Medicare Advantage's popularity has grown.

As of March 12, the Centers for Medicare & Medicaid Services said 154,456 Virginians were enrolled in a Medicare Advantage plan, including 14,924 people in the Roanoke and New River valleys and Bedford County and city. A year ago, 144,931 Virginians were enrolled in a Medicare Advantage plan.

The two largest providers of Medicare Advantage plans in the state each saw gains in enrollment. Humana Inc. grew its plans collectively by 4 percent, capturing 53,338 people. Enrollment in United Healthcare Services plans, which cover about 23,500 people, grew 6 percent.

Still Carilion Clinic, which entered the Medicare Advantage market for the first time this year, blamed the overhaul debate for its lower-than-expected enrollment figures. The Southwest Virginia health care provider had hoped to sign up about 1,000 people; instead it attracted slightly fewer than 200, according to the Centers for Medicare & Medicaid Services.

Enrollment in Anthem's plans fell slightly from 9,337 in March 2009 to 9,116 in March 2010.

Anthem offers a couple of different plans, and while one saw enrollment increase, the other didn't.