Defining Health Systems
The first step in studying health systems is to develop a definition of what constitutes a "health system," which is expected to evolve over time. Below, each Center of Excellence has contributed its own definition as a starting point, as has AHRQ and the Coordinating Center, which it used to develop the Compendium of U.S. Health Systems, 2016.
Dartmouth College Center of Excellence’s Definition of a Health System
The Dartmouth College Center of Excellence defines a health system as an organization that consists of either at least one hospital plus at least one group of physicians or more than one group of physicians. For the purposes of this definition, the group of physicians must include at least three primary care physicians. Dartmouth is studying multiple levels within a system: individual practices, hospitals, and system leadership.
Dartmouth has identified systems and their component entities by looking at the formal corporate relationship among the entities. While independent practices and independent hospitals do not meet the definition of a system, Dartmouth is also studying these entities.
NBER Center of Excellence’s Definition of a Health System
The National Bureau of Economic Research (NBER) Center of Excellence defines health system based on three types of arrangements between two or more health care provider organizations: (1) organizations with common ownership, (2) contractually integrated organizations (e.g., accountable care organizations), and (3) informal care systems, such as common referral arrangements. Systems include organizations combined horizontally (e.g., a hospital system) or vertically (e.g., a multihospital system also owning physician practices and post-acute care facilities).
RAND Center of Excellence’s Definition of a Health System
The RAND Center of Excellence defines a health system as two or more health care organizations affiliated with each other through shared ownership or a contracting relationship for payment and service delivery. For its work, a health system must have at least one acute care hospital and at least one physician organization. For RAND, this excludes "horizontally integrated" health systems, such as systems consisting only of hospitals. Notably, organizations can be members of multiple health systems, such as a physician organization that participates in more than one accountable care organization.
Definition of a Health System Used in AHRQ’s Compendium of U.S. Health Systems, 2016
The Compendium of U.S. Health Systems, 2016, defines a health system as an organization that includes at least one hospital and at least one group of physicians that provides comprehensive care (including primary and specialty care) who are connected with each other and with the hospital through common ownership or joint management. Under this definition, foundation models are considered a form of joint management, while joint participation among providers in an accountable care organization is not, by itself, indicative of joint management. “Group” is not synonymous with a separately organized medical group; hospitals that employ community-based physicians who provide comprehensive care (but are not organized as a medical group) are considered health systems under this definition.