Top 15 independent practice physician groups by number of physicians

According to the American Academy of Family Physicians, an independent physician association (IPA) is a business entity organized and owned by a network of independent physician practices for the purpose of reducing overhead or pursuing business ventures such as contracts with employers, accountable care organizations (ACO) and/or managed care organizations (MCOs).

IPAs are a type of physician group, collectives of physicians—or occasionally individual physicians—acting as an organization to deliver care, usually with a focus on a particular specialty. Definitive Healthcare tracks more than 126,000 physician groups in the U.S., with membership ranging from a single doctor to over 11,000 care professionals.

We’ve compiled a list of the largest IPAs in the U.S. Read on to see which groups have the most member physicians.

15 largest independent physician associations

Rank Physician Group Name Definitive ID City State # of Physicians
1 HealthCare Partners IPA 92755 Garden City NY 5,042
2 U.S. Anesthesia Partners 552756 Fort Lauderdale FL 3,695
3 Hill Physicians Medical Group 550737 Walnut Creek CA 3,586
4 Renaissance Physician Organization 552341 Houston TX 1,387
5 Apogee Physicians 955099 Scottsdale AZ 1,073
6 Upland Medical Group 552023 Chino CA 893
7 Answer Health 585475 Grand Rapids MI 842
8 IPA of Nassau & Suffolk Counties 552273 Commack NY 719
9 Oakland Southfield Physicians 585473 Southfield MI 672
10 Santa Clara County IPA (AKA SCCIPA) 550734 San Mateo CA 589
11 Seoul Medical Group 551964 Long Beach CA 570
12 Physicians Medical Group of San Jose 907136 San Jose CA 558
13 Central Ohio Primary Care 956285 Westerville OH 491
14 Advocare Doctors 956180 Marlton NJ 434
15 Spectrum Healthcare Partners 551050 South Portland ME 433

Fig. 1 Data is from the Definitive Healthcare PhysicianGroupView product. Data is sourced from Definitive Healthcare’s proprietary research and CMS Physicians Compare. Data accurate as of July 2022.

Which independent practice groups are the largest?

HealthCare Partners IPA based in Garden City, New York tops our list of independent practice groups, with 5,042 physicians among its ranks.

U.S. Anesthesia Partners of Fort Lauderdale, Florida comes in second place with 3,695 physicians, while Hill Physicians Medical Group of Walnut Creek, California takes third with 3,586 physicians.

Generally speaking, larger practice groups are more likely to have the financial resources necessary to support routine business functions, administration and care services. Plus, larger groups usually maintain larger patient bases, providing a more stable income stream and a greater tolerance for financial risk.

Aside from the financial benefits they offer, physicians may be attracted to larger practice groups for potential work-life balance benefits—especially as burnout rates rise following COVID-19. The greater number of physicians in a group, the more comprehensive coverage that group can provide without stretching its members’ availability thin.

What is the difference between an IPA and an accountable care organization (ACO)?

IPAs and ACOs are similar in that they’re both networks of providers who collaborate to deliver coordinated care within a specific patient population. However, the two models are different in important ways.

ACOs are specifically designated by the Centers for Medicare and Medicaid Services (CMS) under the Medicare Shared Savings Program to incentivize greater coordination in value-based care. ACO members are awarded with greater reimbursements when their organization demonstrates improved patient outcomes and reduced care costs.

IPAs, on the other hand, are formed by its members to share financial, technological and staffing resources, and to improve members’ bargaining power with employers and other organizations.

An IPA is owned and operated by a network of independent physician practices, while an ACO can comprise doctors, hospitals and other healthcare providers. An IPA—or its individual members—may opt to join an ACO or negotiate with one to secure resources or implement system-wide improvements.

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