Washington-based health systems CHI Franciscan and Virginia Mason have integrated to form Virginia Mason Franciscan Health, according to a news release Tuesday announcing the new organization.

Combined, the two health care systems — which announced last July they were exploring formation of a joint operating company — offer about 300 care sites in western Washington, including the Eastside. CommonSpirit Health, a nonprofit Catholic health system based in Chicago and the parent company of CHI Franciscan, is the parent of the new Virginia Mason Franciscan Health.

Initially, two CEOs will lead Virginia Mason Franciscan Health.

“Virginia Mason Franciscan Health has an incredibly strong foundation to build upon as our two storied organizations come together with an exciting vision, particularly as we expand services for the most vulnerable in our communities,” Ketul J. Patel, CEO of Virginia Mason Franciscan Health and president of the Pacific Northwest Division of CommonSpirit Health, said in the news release. Patel was formerly CEO of CHI Franciscan and president of the Pacific Northwest Division at CommonSpirit Health. “We are committed to building a consumer-focused health care system while expanding our presence as a national leader in the transformation of health care delivery.”

Dr. Gary S. Kaplan, CEO of Virginia Mason Franciscan Health and formerly chairman and CEO of Virginia Mason, said: “Today is a great day for our organization and our community. For years we have worked with CHI Franciscan, but now, together, our potential is limitless. We will be able to apply learnings across our entire system that not only improve the patient experience, but also change health care delivery for the better.”

Virginia Mason Franciscan Health will operate 11 hospitals and nearly 300 sites of care, including primary and specialty care clinics, same-day surgery centers, Benaroya Research Institute, Bailey-Boushay House, and Virginia Mason Institute. The organization will employ more than 18,000 people, including nearly 5,000 employed physicians and affiliated providers.

All patients will continue to use their same site of care and will continue to use their current insurance plans. Each organization will update patients before any changes take place, the release said.

CHI Franciscan and Virginia Mason previously partnered on obstetric and women’s health – opening a new birth center and women’s health clinic in Seattle last year – as well as a radiation oncology partnership at St. Anne Hospital in Burien and St. Francis Hospital in Federal Way. Those partnerships proved positive and will serve as the model for integration across the system, the release said.

CommonSpirit Health operates 137 hospitals and more than 1,000 care sites across 21 states.