On 12/23/2013, Medicare announced 123 new Accountable Care Organizations, covering approximately 1.5 million more Medicare beneficiaries. The list of new ACOs may be found here: ACOs with start date 1/1/2014.

Lists of ACOs previously announced are here:

• Start date April 1, 2012 (27 ACOs, ~375,000 beneficiaries in 18 States)
• Start date July 1, 2012 (87 ACOs)
• Start date January 1, 2013 (106 ACOs)

With the 1/1/2014 start date of 123 new ACOs, an estimated 4.3 million Medicare beneficiaries are provided care through some 343 ACOs. What’s the growth looked like? What’s the ACO penetration of the Medicare beneficiary population? Here are some answers.

Source:  Advantage plan enrollees.

The percent of Medicare beneficiaries covered by ACOs remains relatively low at this time [about 8.8% of approximately 49.4 million (Kaiser Family Foundation)], and is lower than participation rates in the early years of “Medicare+Choice,” “Advantage” (Part C) plans. Only time will tell whether the number of beneficiaries receiving care through an ACO may approach or even overtake the number in Part C plans.