But Berwick kept the tone upbeat. "People do sense we're on the threshold of an important and productive change and we're coming up with a workable and promising framework," he said.
Some organizations such as Kaiser Permanente have said that they do not plan to apply to become an ACO for their population of Medicare patients because under their current model, they already have the elements of an accountable care and their care would not benefit.
Kaiser CEO George Halvorson has said that Kaiser provides care for its 8.8 million beneficiaries using the essential elements of an ACO right now.
In an interview with HealthLeaders Media last month, he said, "I think the payment structure defined in the ACO regs is an interim step toward getting people to function as an accountable care organization. And I think it is directionally correct. It is not as good as a Medicare Advantage program where you receive full prepayment for the care of the patient. This is a partial prepayment."
It isn't clear whether the Pioneer model might prompt Kaiser to change its mind.
The American Medical Association's immediate past president J. James Rohack, MD, said in a statement that Berwick's alternative proposals Tuesday take "a step in the right direction, but more action is needed to ensure all physicians who wish to do so can lead and participate in Medicare ACOs."
He added that the AMA believes the benefits of ACOs "cannot be fully realized unless physicians in all practice sizes can be involved. According to the AMA physician practice survey, 78 percent of office-based physicians in the United States work in practices with nine physicians or less. The AMA has encouraged CMS to provide assistance for physicians in small practices, including startup capital and small business loans, to meet the large initial expenses that will come with participation in ACOs.
Some other providers also were not persuaded.