The Centers for Medicare and Medicaid Services has announced that Eighty-nine new accountable care organizations (ACOs) have joined the Medicare Shared Savings Program (MSSP) effective January 1.

This brings the total number of ACOs participating in the Shared Savings Program to 405 and increases the number of beneficiaries served to more than 7.2 million. When added to the Pioneer ACO program that brings the total number of ACOs to 424 serving 7.8 million beneficiaries.

According to Sean Cavanaugh, deputy administrator and director for the Center for Medicare, the addition of the new ACOs will add about 23,000 new providers to the program, on top of the 17,000 who joined the MSSP in 2014.

“The growth of this program for providing health care has been continued and consistent since its inception, and we are encouraged by that interest,” Cavanaugh wrote in a blog on cms.gov. He pointed out that the program is providing “promising results.”

For example, MSSP ACO’s improved on 30 of the 33 quality measures over the first two years of the program, and also outperformed group practices reporting quality on 17 out of 22 measures Cavanaugh also pointed out that these promising results extend to increased costs savings, with a combined total program savings of $417 million for the MSSP and the Pioneer ACO model.

Click here for a list of the 89 new ACOs.