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Top 10 ACOs by Patient Population

May 17, 2018 BY Alanna Moriarty

Top 10 ACOs by Patient Population

An Accountable Care Organization (ACO) is a voluntary coalition of healthcare providers characterized by a care delivery and reimbursement model tying provider payments to quality metrics and patient care outcomes. The goal of the ACO model is to reduce total care costs for a specific patient population. Each ACO has a defined patient population for which it is held accountable in terms of care cost and quality. Patient populations are primarily comprised of Medicare beneficiaries.

All but one of the top 10 ACOs with the largest patient populations are commercial ACOs--the exception is one Medicare Next Generation ACO. Commercial ACOs are reimbursed by commercial payers or self-insured employers and do not have public reporting requirements, unlike those associated with the Centers for Medicare and Medicaid Services (CMS). A Leavitt Partners analysis found that commercial ACOs covered more than 17 million lives as of April 2016, more than twice that covered by Medicare and Medicaid ACOs. Many Commercial ACOs emulate the Medicare Shared Savings Program (MSSP) model, reimbursing provider services and comparing the total costs to a benchmark every year.

Top 10 ACOs by Patient Population
ACO Name Patient Population ACO Type
TMA PracticeEdge 5,000,000 Commercial ACO
Texas Health Resources ACO 1,600,000 Commercial ACO
Childrens Hospital of Philadelphia (CHOP) ACO 1,400,000 Commercial ACO
Delaware Valley ACO 1,400,000 Commercial ACO
Steward Integrated Care Network 1,000,000 Medicare Next Generation ACO
Carilion Clinic ACO 1,000,000 Commercial ACO
Heritage Medical Group ACO 700,000 Commercial ACO
Healthcare Partners ACO 675,000 Commercial ACO
Riverside Health System ACO 500,000 Commercial ACO
Partners in Care ACO 500,000 Commercial ACO

Fig 1 Data from Definitive Healthcare based on ACO self-reporting and CMS Programs. The Definitive Healthcare database tracks financial and performance metrics on over 1,500 ACOs.

To succeed in a commercial ACO, providers must be able to manage value-based reimbursement, which relies heavily on new technology, a smooth administrative process, and a culture shift in the participating care facility. ACO participants are required to understand the patient experience across the entire healthcare continuum, which can mean investing in a hospital's physician network to ensure optimal control over patient care. Once facilities opt to join an ACO, the organization as a whole has the option to participate in various care improvement and value-based programs, such as the MSSP.

The MSSP was announced in 2010 as an incentive for providers to collaborate on improving patient care coordination and reducing care costs. Under the Shared Savings Program, participating ACOs can choose from four different "tracks," each with unique requirements and rewards. The primary issue with this method is that the vast majority of ACOs choose Track 1, which absolves participants from risk and does not require them to repay Medicare for overspending. However, while ACOs are not penalized for overspending, they are also unable to collect bonus payments in the form of generated shared savings. 

In addition to care facilities and payers, independent physicians are also able to participate in the MSSP. This allows independent practitioners to benefit from value-based CMS initiatives, empowering them to invest in new technologies, aggregate performance and quality data, and more easily complete CMS reporting requirements. Participation in an ACO minimizes the workload of independent physicians, enabling them to spend more time seeing patients and less time logging data. Health systems and local hospitals also benefit when independent physicians participate in an ACO. Solo practitioners are more likely to refer patients to hospitals and health systems in the same ACO, expanding their patient population without hiring additional care providers and saving a hospital or health system money.

Top 10 MSSP ACOs by Total MSSP Expenditures
ACO Name Total MSSP Expenditures (M) Patient Population
Advocate Physician Partners Accountable Care $1,493 139,617
Delaware Valley ACO $1,376 123,888
Physicians Accountable Care Solutions $1,143 115,415
Physician Organization of Michigan ACO $1,000 104,559
Southwestern Health Resources Accountable Care Network $977 87,479
Iowa Health Accountable Care LC $823 92,589
Mercy Health ACO $816 82,614
Meridian ACO $803 63,249
Genesis Healthcare ACO $784 15,787
Illinois Health Partners ACO $745 81,093

Fig 2 Data from Definitive Healthcare based on CMS reports.

Experts acknowledge that the shift from fee-for-service to value-based care is the future of medicine and care delivery. The challenge is how to implement these changes quickly and effectively, without compromising care coordination or patient experience. Because commercial ACOs do not have public reporting requirements, it is difficult to gather the data required to assess industry progress. This industry-wide movement toward value-based care means physicians must adapt to new methods of care delivery and reporting, which could mean greater opportunities for strong physician leaders. Physician workflow is increasingly data-oriented, leading to a heavy reliance on electronic health record (EHR) systems. This can be frustrating for physicians, as they are often forced to spend less time meeting with patients in-person, and more time logging the details of the patient visits. Physicians who are most easily able to adapt their workflows can pave the way for others in their facility and ACO.

Visit the Definitive Blog to read more about MSSP ACOs and population health trends.

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