A dozen doctors have lost their positions after a Honolulu hospital switched to a new employment contractor, officials said.

The Queen's Medical Center physicians belonged to Medical Specialists of Hawaii, which has held a contract with the hospital to care for surgical patients for the past decade, The Honolulu Star-Advertiser reported Sunday.

The hospital has hired Envision Healthcare Corporation of Nashville, Tennessee, one of the nation's largest physician-staffing companies, which is owned by private equity firm KKR & Co. Inc.

Patient care and physician coverage are not expected to be impacted by the change, said Rick Bruno, hospital vice president for patient care.

"All of the affected physicians working under MSH were offered employment through Envision or the Queen's Medical Group," Bruno said. "All of them remain active members of our medical staff, which allows them to continue to see patients at Queen's."

The 12 independent physicians are all hospitalists, a category of doctors who care for patients only while they are in the hospital. They retain hospital privileges, but are no longer paid or contracted to care for patients there. The doctors were offered positions with Envision, but none accepted, officials said.

Bruno did not respond to questions about how Envision plans to staff the hospital or the company's billing practices, the Star-Advertiser reported.

Envision has faced national scrutiny for reports of charging insurers and patients higher rates than warranted, as well as not informing patients the company would not participate with certain health insurance providers, resulting in large bills, the newspaper reported.

Envision representatives did not respond to requests for comment.