More Group Practices and Doctors Join Health Systems, New Data Finds

The number of doctors in group practices (those with more than one physician billing traditional Medicare) who were affiliated with vertically integrated health systems increased 5 percentage points, from 56.9 to 61.9 percent, between 2018 and 2022, according to new data on group practices released by the Agency of Healthcare Research and Quality (AHRQ).

These findings come from AHRQ’s Compendium of U.S. Health Systems, the leading public resource for studying health care organizations. Mathematica partnered with AHRQ to release six new files as part of the Compendium, including the Group Practice linkage files for 2020 through 2022, which include information on system affiliation, size, and traditional Medicare billing activity for the nation’s 35,448 group practices during the COVID-19 public health emergency.

States, health care leaders, and researchers can use these publicly available resources to better understand the structure of health systems, identify specific trends in consolidation in different areas or for various types of provider organizations, and address pressing questions about costs, quality, and access to care locally and nationally.

The new data reveals additional insights on how providers and health care organizations continue to reorganize. Physician group practices are getting larger, and those affiliated with health systems tend to be much larger compared to those that are not. Between 2018 and 2022, the average number of doctors per group practice regardless of affiliation increased from 15 to 18, while the size of group practices affiliated with health systems increased from 54 to 66 doctors per practice on average.

In addition to the Group Practice linkage files, the new files also include the following:

• 2023 Outpatient Site linkage file, which contains street-level information on 279,446 sites. This information complements data on ownership relationships and system affiliations and can be used to classify sites by type, including primary care and behavioral health.
• 2023 Hospital linkage file, which includes 6,800 hospitals and contains data on system affiliation, corporate parents, size, and revenue.
• System files, the cornerstone of the compendium, which now include 2023 data and continue to provide key measures of size, composition, insurance offerings, and systemwide hospital revenue for the 639 systems in the Compendium in 2023.

Mathematica partnered with AHRQ to develop, enhance, and analyze data from the Compendium of U.S. Health Systems as part of AHRQ’s Comparative Health System Performance Initiative.