"If you're reducing the size of the panel, it could be six months or it could be a year, and that doesn't bode well for the patients," he said. "I think this is really mind-boggling."

Subbarao said he doesn't know why some doctors were de-selected from the Medicare Advantage plan.

"I don't know if they even had ttime to present their case," he said. "We are professionals and we expect the same professional courtesy with everone we deal with."

He said his office has reached out to UnitedHealthcare officials to find out more about why they've taken this step.

"I think it is clearly driven by the finances," he said. "I'm not saying the financial situation shouldn't be part of the equation. If it's the whole equation, and that's what it sounds like, then we have a problem."

Dr. Robert Lapkin said his New Britain-based practice, Nephrologic Associates, received a letter Monday from UnitedHealthcare stating that it was being dropped from the company's Medicare Advantage network. The Hospital of Central Connecticut with its two locations in New Britain and Southington is the primary hsopital for Lapkin's practice. The practice also does consultation work for Bristol Hospital.

"I guess they're trying to get leaner, with fewer specialists," he said in a phone interview Wednesday.

He said the "sweeping drop of specialists" will mean that many patients will have travel out of the area to get treatment. About 160 of his practice's patients are covered under United's Medicare Advantage plan.

"We're the only nephrologists in the greater New Britain area," he said. "We have a fair number of dialysis paitents who are insured under the UnitedHealthcare Medicare Advantage plan. I don't know who's going to take care of them."

Lapkin said his office manager called the insurance company about why his practice was dropped, but "didn't get any answers."

"We'll be contacting our congressional delegation, and maybe they can change this," he said.

Advocates React

Margaret Murphy, associate director for the Center for Medicare Advocacy, said the change could lead to many problems.

"I don't think this was well-thought-out or being well-implemented," she said. Because many of the people affected will be older, she said, some might not be particularly savvy when it comes to insurance and could end up with plans that they don't want.

"There could be older people or their caregivers who don't pay attention [to the notices] or don't realize that their doctors are out of network, and now they're faced with extra expenses," she said.

Murphy said the timing of the change is particularly fraught, since Medicare enrollment begins Oct. 15. And she said many officials from the Centers for Medicare and Medicaid Services, who would nomally be available to help, are on furlough as a result of the federal government shutdown.

Murphy said one solution for patients whose doctors have been dropped from their Medicare Advantage would be to enroll in traditional Medicare. Most doctors participating in Medicare Advantage will accept Medicare payments, she said.

Victoria Veltri, the state healthcare advocate, said this is the first time she can remember an insurance company dropping this many doctors. Particularly troubling, she said, is the plan to drop 810 primary care physicians.

"That raises some concerns because health care is shifting so that we're relying more on primary care physicians," she said. "And I just don't know right now what the loss of 800 of these doctors will do. I think we need to answer that question: Where are these providers and how many patients are they seeing?"

Veltri said she UnitedHealthcare officials agreed Wednesday to meet with her to discuss details of the plan. The date of the meeting hadn't been set as of late Wednesday.

O'Brien, the regional president of UnitedHealthcare Networks, said the factors that influenced the company's decision are not unique to UnitedHealthcare.

"Making changes to the design of networks for specific markets and products is not new," O'Briens said. "It is a necessary part of conducting our business as we work to achieve the triple aim of better health, better care and lower costs."

Aetna and Anthem Blue Cross and Blue Shield in Connecticut said Wednesday that they are not planning any cuts to their physician networks comparable to UnitedHealthcare's decision though both said they are constantly reviewing those networks.