Healthcare Insights

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

RankPhysician group nameDefinitive IDCityState# of physiciansExplore dataset
1HealthCare Partners IPA92755Garden CityNY5,042Explore
2U.S. Anesthesia Partners552756Fort LauderdaleFL3,695Explore
3Hill Physicians Medical Group550737Walnut CreekCA3,586Explore
4Renaissance Physician Organization552341HoustonTX1,387Explore
5Apogee Physicians955099ScottsdaleAZ1,073Explore
6Upland Medical Group552023ChinoCA893Explore
7Answer Health585475Grand RapidsMI842Explore
8IPA of Nassau & Suffolk Counties552273CommackNY719Explore
9Oakland Southfield Physicians585473SouthfieldMI672Explore
10Santa Clara County IPA (AKA SCCIPA)550734San MateoCA589Explore
11Seoul Medical Group551964Long BeachCA570Explore
12Physicians Medical Group of San Jose907136San JoseCA558Explore
13Central Ohio Primary Care956285WestervilleOH491Explore
14Advocare Doctors956180MarltonNJ434Explore
15Spectrum Healthcare Partners551050South PortlandME433Explore

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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