The Federal Trade Commission (FTC) in the US has lodged an antitrust lawsuit to block John Muir Health's planned $142.5m deal for taking full ownership in San Ramon Regional Medical Center from Tenet Healthcare.

The agency argues that the deal would eliminate competition between John Muir Health and San Ramon Regional Medical Center in California's I-680 corridor, leading to higher healthcare costs.

This complaint alleges that the acquisition would give John Muir Health control over more than 50% of the market for inpatient general acute care services in the region.

According to the agency, this would result in increased insurance premiums, co-pays, and other out-of-pocket costs for commercial health insurance enrollees.

The FTC and the California Attorney General's office are jointly filing a complaint in federal court and seeking a temporary restraining order to prevent the transaction pending an administrative proceeding.

This complaint asserts that the proposed deal would reduce incentives for quality improvements in healthcare services in the affected region.

FTC Bureau of Competition director Henry Liu said: “San Ramon Regional Medical Center has played an important role in ensuring Californians in the I-680 corridor have access to quality, affordable care for critical health care services, such as cardiac surgery and childbirth.

“John Muir’s acquisition of San Ramon Medical would increase already high health care costs in the area and threaten to stall quality improvements that help advance care for all patients.”

John Muir Health comprises two prominent medical centres, the Walnut Creek Medical Center and the Concord Medical Center.

Besides, it operates urgent care centres and provides primary care and outpatient services.

Its physician network includes more than 1,000 primary care and specialist physicians, and its medical group consists of 350 clinicians.