Catholic Health Initiatives, which jointly operates Colorado’s largest hospital group, Centura Health, has signed a merger agreement with Dignity Health that will create a new nonprofit Catholic health group based in Chicago.

CHI, based in Arapahoe County near the Interstate 25 and E-470 interchange, employs about 720 people in the metro area, not counting Centura Health workers, and is one of the largest headquarters in Colorado based on revenue. Dignity Health is headquartered in San Francisco.

The two systems will bring together hospitals and clinics across a 28-state region. Chicago was chosen as the base for handling the integration because of its central geographic location and flight access, a CHI spokesman said Thursday.

“We are joining together to create a new Catholic health system, one that is positioned to accelerate the change from sick care to well care across the United States,” Kevin Lofton, chief executive officer of CHI, said in a statement issued Thursday.

CHI spokesman Michael Romano said it’s too early to know what impact the combination will have on specific jobs, departments, or services.

“We expect integration to take place over one to two years after the combination is complete, during which time we will operate in some ways as separate organizations,” he said.

CHI’s existing offices in metro Denver; Erlanger, Ky.; and Fargo, N.D., will remain open and employees at those locations won’t be required to move during the integration, Romano said.

But some streamlining will occur at some point, he added.

CHI was formed in 1996 through the consolidation of four Catholic health systems. That same year, CHI teamed with Adventist Health System to jointly operate Centura Health, which has 17 hospitals in Colorado and is based in Centennial.

CHI operates 100 hospitals and 30 critical care facilities in 17 states. It reported $15.5 billion in revenues and owned assets valued at $21.9 billion in its most recent fiscal year.

Dignity Health got its start in 1986 when two congregations of the Sisters of Mercy combined. It has 400 care centers and a network of more than 9,000 doctors across a 22-state region. The 39 hospitals it operates are located in California, Arizona and Nevada.

Dignity Health generated $12.9 billion in revenues and owns assets valued at $17.4 billion. Both nonprofits provided more than $2 billion each in charity care the past year.