Accountable care organizations (ACOs) will be allowed to participate in the Comprehensive Primary Care Plus (CPC+) pilot program.

The change in the model was announced on Twitter May 27 by Andy Slavitt, Acting Administrator for the Centers for Medicare & Medicaid Services (CMS), and included in an updated fact sheet by the agency.

“Primary care practices currently participating or considering participation in Tracks 1, 2 or 3 of (the Medicare Shared Savings Program) that meet the eligibility requirements of CPC+ may participate in both initiatives,” the agency said.

There are limits on ACO participation in the pilot. Practices participating in the ACO Investment model or the Next Generation ACO model aren’t eligible for CPC+, and CMS will cap ACO participation at 1,500 practices of the 5,000 total in the program. If more than 1,500 eligible ACOs apply, a lottery will determine which get into CPC+.

The CPC+ program was first unveiled in April. The model introduces monthly fee-based tracks of care, with the goal of improving flexibility for physicians to care for patients, rather than submit a Medicare claim after the service has been performed. It will be implemented in up to 20 regions beginning in January 2017, involving 20,000 doctors and an estimated 1 million patients.

When the initial proposal left out ACOs, some health policy experts were quick to call for their inclusion, like an April blog post by Aledade CEO Farzad Mostashari, MD, Schaffer Center for Health Policy and Economics Senior Fellow Bob Kocher, MD, and Duke-Margolis Center for Health Policy Director Mark McClellan, MD, PhD.

“We believe that the CPC+ program would gain substantially more adoption, bring in more commercial partners, have a greater impact on lowering total cost of care and accelerate the Administration’s policy of moving more physicians to value-based care if there was a CPC+ACO arm in the CPC+ pilot,” the three wrote.

Kocher supported the change allowing ACO participation on Twitter.

“By listening to doctors, CMS is creating a better model to improve quality and cost,” Kocher tweeted.

The next step for CPC+ is for interested payers to submit proposals by June 8. CMS will then announce the regions involved in the pilot by June 15.