While accountable care organizations have been a hot topic in the health care provider community since their inclusion in the Affordable Care Act, public awareness of ACOs is still relatively low. ACOs participating in the federal shared savings program administered by the Centers for Medicare & Medicaid Services are required to inform all beneficiaries of their enrollment while patients can't opt out of ACOs, they can stop their physicians and hospitals from sharing their data with other participants.

Earlier this year, Atlantic ACO in New Jersey, a collaborative effort between Atlantic Health and Valley Health System, notified its 50,000 Medicare beneficiaries via mail of their enrollment in the ACO; roughly 350 patients called a hotline set up for patients seeking further information.

David Shulkin, M.D., president and CEO of Morristown Medical Center, one of the ACO's member hospitals, says many patients were concerned about the veracity of the letter, noting that criminals sometimes target the elderly with fraudulent requests.

"When they got a letter that we were going to be sharing [their] data, many wanted to confirm this was legitimate," Shulkin says.

Callers were reassured that the letter was legitimate and were informed of the ACO's potential benefits to their care. Only 11 percent of callers still decided to opt out of data sharing.

"Some of them don't want the government involved in any of their data," Shulkin says.

For the beneficiaries who remain on board, Atlantic ACO officials say they hope the experiment will help realign a traditionally high-cost, fragmented market where few physician groups are affiliated with hospitals. ACO members already are beginning to meet and develop new best practices around congestive heart failure, says Marc Goldstein, vice president for physician services at Valley Health.

"This is an experiment hospitals, physicians and nursing homes can take on with very little risk and learn to work together for the benefit of patients," Goldstein says.