Seventeen more accountable care organizations (ACOs) have joined CMS’s Next Generation ACO model, the most advanced and high-risk available to ACOs in Medicare.

While three health systems left the program, the additions bring the total number of participants to 58 for 2018 with participants serving about two million Medicare beneficiaries. California has the highest number of participants of any state with eight, followed by seven in Massachusetts.

“The interest and growth in participation in the Next Generation Model shows that ACOs are increasingly driving change and pushing healthcare delivery and payment reform forward in new and innovative ways. These ACOs are trailblazers and we congratulate them for their work,” said Clif Gaus, President and CEO of the National Association of ACOs (NAACOS).

Since the transition to a new CMS administration, results and new participants in Next Generation and other ACO models have been less publicized, along with others being outright canceled. The models have achieved savings, however. In 2016, the first year of Next Generation ACO, 11 of its 18 participants generated gross savings of $71 million, being paying $58 million in bonuses. The other seven ACOs owed $23 million in losses, $20 million of which had to be paid back. All 18 ACOs scored 100 percent across 33 quality measures.

The larger Medicare Shared Savings Program (MSSP) generated larger savings of $652 million in the same year. That program has also grown, welcoming 124 new entrants in 2018 covering a total of 10.5 million beneficiaries. Most of those ACOs are participating in the upside-only Track 1 of MSSP, but a growing share (18 percent in 2018) opted to take on downside risk, largely thanks to the addition of the new risk-based Track 1+.

A full list of Next Generation ACO participants for 2018 can be found here.