Washington, D.C.—Thousands of providers could find their federal quality ratings downgraded as the Obama administration prepares to make sweeping changes to its Five-Star rating program.

The Centers for Medicare & Medicaid Services on Thursday is expected to announce that it is rebasing its quality metrics, according to sources close to the agency. Some speculate that 10 to 15 percent of providers could lose at least one star, maybe even two, as a result of the changes.

It’s a whipsaw moment for many providers, who just saw their sector praised by CMS earlier this week when it released a report showing that the off-label use of antipsychotics for long term care residents had been reduced by 19.4 percent, well above an earlier goal of 15 percent.

“It sends the wrong message that quality in today’s skilled nursing centers is on the decline when nearly every quality marker—both in and outside of Five-Star—point to quality improving in our centers nationwide,” says Greg Crist, spokesman for the American Health Care Association/National Center for Assisted Living. The rebasing effort is bound to sow confusion for residents and families, he says.

For some provider advocates, it’s also a bitter irony: Many providers resisted the Five-Star system at the outset, worried that they couldn’t get fair analyses from regulators. But, having embraced the system—however grudgingly—the sector excelled: Nearly half of the nation’s long term and post-acute care centers have achieved either four- or five-star ratings.

“They’re moving the goal posts,” Crist says.

Bill Myers is Provider’s senior editor. Email him at wmyers@providermagazine.com. Follow him on Twitter, @ProviderMyers.