No longer. In 2013, the clinic hired oncology nurses to take patient calls and gave them protocols: For example, a chemo patient with a fever gets a same-day appointment and certain tests.

Baird said the program prevented 500 visits to the E.R. in 2016. “We were able to achieve Medicare’s ‘triple aim’: higher quality of care, lower cost and increased patient satisfaction,” he said.

Cancer causes suffering. Cancer patients take strong, toxic medicines. They need same-day appointments. But neither Medicare nor private insurers reimburse a practice for solving problems over the phone.

The Affordable Care Act allowed Dayton to make the switch. Since 2010, the A.C.A.’s Center for Medicare and Medicaid Innovation has run, financed or partnered with states to do demonstration projects with 61,000 providers, testing dozens of different ideas. This allows people to try new things, measure the results, and then scale up what works. People all over the country are showing that better, less expensive care is possible.

“This is a vehicle for experimentation,” said Barbara McAneny, chief executive of the New Mexico Cancer Center. “We need as many doctors’ thinking about what they can do better for their patients as they possibly can.”

Republicans in Congress have objected to what they consider the Innovation Center’s overreach. “There have been some concerns about how wide and how mandatory the pilot programs will be,” said Mark McClellan, who ran the Centers for Medicare and Medicaid Services under President George W. Bush and is now a professor at Duke. But like the shift away from fee for service, experimentation itself has bipartisan support. “The concerns are not about the concept of piloting and expanding new approaches for payment,” he said.

More than a third of Medicare payments to providers now depend on value instead of volume. This has already helped to hold down costs. And value-based payments will get a huge increase from a law kicking in this year that moves Medicare payments of physicians away from fee for service. The law passed with overwhelming bipartisan support — and it can’t work without the Innovation Center’s projects.