Physicians and hospitals have formed 106 new accountable care organizations to participate in the Patient Protection and Affordable Care Act's Medicare Shared Savings Program, the Centers for Medicare & Medicaid Services announced yesterday. Fifteen of the groups will participate in the program's Advance Payment Model, which provides advance payment of expected shared savings to rural and physician-based ACOs that would benefit from additional start-up resources. MSSP participants agree to be held accountable for improving the health and experience of care for Medicare fee-for-service beneficiaries while reducing the rate of growth in health care spending. To date, more than 250 organizations have formed Medicare ACOs, which are expected to serve more than 4 million beneficiaries. About half of the ACOs are physician-led organizations serving fewer than 10,000 beneficiaries, and about 20% include community health centers, rural health centers and critical access hospitals that serve low-income and rural communities, CMS said. Additional hospitals and physicians can apply to the program this summer.