Healthcare Insights

Top 25 Accountable Care Organizations by Population

An Accountable Care Organization (ACO) is a formal group of physicians, hospitals, or other care providers that voluntarily work together to deliver high-quality coordinated care to Medicare beneficiaries. The goal of an ACO is to provide affordable care through reducing or eliminating unnecessary duplication of tests or services, lowering the risk of medical errors. For each ACO, there is a defined patient population, primarily composed of Medicare beneficiaries, for which it is held accountable in terms of care cost, gross savings, and quality.

The following list highlights the top 25 ACOs by patient population, representing over 16.4 million patients with an average population of 657,000. Of the top 25, 84 percent are classified as commercial ACOs— an ACO model with a non-government payer.

TMA PracticeEdge, a commercial ACO based out of Austin, TX, ranks first with a patient population of five million — 112-percent higher than the next highest ACO, Aetna-Children’s Hospital of Philadelphia (CHOP) which has a patient population of 1.4 million.

Top 25 Accountable Care Organizations by Patient Population

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Rank	Definitive ID	ACO Name	ACO Type	City	State	ACO Start Date	Patient Population
1	810909	TMA PracticeEdge (Texas Medical Association - Blue Cross and Blue Shield of Texas ACO)	Commercial ACO	Austin	TX	2015 Q1	5,000,000
2	842940	Aetna - Childrens Hospital of Philadelphia (CHOP) ACO	Commercial ACO	Philadelphia	PA	2015 Q4	1,400,000
3	552096	Steward Integrated Care Network (AKA Steward Promise)	Medicare Shared Savings ACO	Needham	MA	2016 Q1	1,000,000
3	552289	Aetna - Carilion Clinic ACO	Commercial ACO	Roanoke	VA	2011 Q3	1,000,000
5	552388	Capital Bluecross - Heritage Medical Group ACO	Commercial ACO	Lemoyne	PA	2011 Q2	700,000
5	552068	Atrius Health Pioneer ACO (Closed - Left Pioneer Program)	Medicare Pioneer ACO	Newton	MA	2012 Q1	700,000
7	579844	Anthem Blue Cross of California - Healthcare Partners ACO	Commercial ACO	El Segundo	CA	2013 Q4	675,000
8	579912	Aetna - Riverside Health System ACO	Commercial ACO	Newport News	VA	2013 Q2	500,000
8	585269	Horizon Blue Cross Blue Shield of New Jersey - Partners in Care ACO	Commercial ACO	East Brunswick	NJ	2014 Q1	500,000
10	823406	Aetna - Virtual Medical Group ACO	Commercial ACO	Marlton	NJ	2015 Q1	400,000
11	552285	Advocatecare ACO	Commercial ACO	Chicago	IL	2011 Q1	375,000
11	969400	BCBS Illinois - Advocate Physician Partners Accountable Care	Commercial ACO	Rolling Meadows	IL	2012 Q3	375,000
13	969315	BCBS Arizona - Banner Health Network ACO	Commercial ACO	Phoenix	AZ	2012 Q1	350,000
13	552349	Cigna - Penobscot Community Health Care ACO (Closed)	Commercial ACO	Bangor	ME	2012 Q2	350,000
13	553402	Cigna - Banner Health Network ACO	Commercial ACO	Phoenix	AZ	2012 Q4	350,000
16	577487	UnitedHealthcare - Seton Health Alliance ACO	Commercial ACO	Austin	TX	2013 Q3	320,000
17	578002	Partners for Kids ACO	Medicaid ACO	Columbus	OH	2012 Q3	300,000
17	552067	Allina Health Pioneer ACO (Closed - Left Pioneer Program)	Medicare Pioneer ACO	Minneapolis	MN	2012 Q1	300,000
17	969460	HealthPartners - Northwest Metro Alliance	Commercial ACO	Bloomington	MN	2010 Q1	300,000
20	585460	Blue Shield of California - EPIC ACO	Commercial ACO	Redlands	CA	2014 Q1	273,000
21	835846	University Hospitals - Anthem Blue Cross and Blue Shield ACO	Commercial ACO	Cleveland	OH	2015 Q3	270,000
22	849729	Humana - DeKalb PHO ACO	Commercial ACO	Decatur	GA	2016 Q1	250,000
22	858080	DeKalb Medical Physicians Group - UnitedHealthcare ACO	Commercial ACO	Decatur	GA	2016 Q3	250,000
22	947978	Cigna - DeKalb Physicians Health Organization	Commercial ACO	Decatur	GA	2015 Q4	250,000
25	552351	Cigna - Westmed Medical Group ACO	Commercial ACO	Rye Brook	NY	2012 Q2	237,000

Fig 1.  Data from Definitive Healthcare from the Accountable Care Organizations Database. Data is from the Center for Medicare & Medicaid Services and Definitive Healthcare proprietary data. Most recent data available, accessed in January 2021.