Stalled contract negotiations between UnitedHealthcare, the health insurance giant, and Mount Sinai Health System, a leading New York City hospital system, are forcing tens of thousands of New Yorkers to switch doctors or risk paying out-of-network prices.

The impasse has dragged on for months. Mount Sinai has sought to raise prices significantly, but the insurance company has refused to agree to pay the new proposed rates. As a result, Mount Sinai’s hospitals are now out of network for patients insured by UnitedHealthcare or Oxford, which are subsidiaries of the same company.

But the issue is about to become even more urgent for many patients because many Mount Sinai affiliated doctors — in addition to the hospitals themselves — are about to be removed from UnitedHealthcare’s network, starting March 22. That means patients with United who have employer-sponsored or individual plans will be billed out-of-network rates when they see a Mount Sinai affiliated doctor at a doctor’s office.

The negotiations have sent many patients scrambling to find new doctors. UnitedHealthcare says about 80,000 Mount Sinai patients are affected.

What Happened?

The dispute between the insurance giant and the hospital system is a rare instance in which health care contract negotiations have spilled into public view.

Mount Sinai sought to negotiate better rates with UnitedHealthcare, demanding that the insurance giant pay the hospital more for doctor visits and hospital stays. United claims Mount Sinai was asking for rates to go up some 58 percent over the next four years.

Mount Sinai says it asked for a significant increase because it recently learned that UnitedHealthcare was paying Mount Sinai significantly less per medical procedure than it was paying other top New York City hospitals.

Mount Sinai estimates that another hospital system, NewYork-Presbyterian receives about 40 percent more from UnitedHealthcare than Mount Sinai does for many common procedures.

Hospitals and health insurers negotiate “in network” rates individually. The prices were often treated as secret, and hospital executives often had only a vague idea of what insurance companies paid their competitors for similar care. But that has changed with recent laws and regulations that have required hospitals to publish information about rates.

“It is something we thought for many years by speaking to colleagues at other institutions, but we were able to prove in 2023 because of the new transparency laws,” said a Mount Sinai obstetrician-gynecologist, Dr. Alan Adler, who has been involved in the negotiations with United.

That set the stage for the current dispute: Mount Sinai wanted United to pay them more in line with the competition, while United wanted to keep costs down. It has called the hospital network’s demands “outlandish.”

In a statement, UnitedHealthcare said the two parties were in “active discussions,” and said it had “provided the health system with multiple proposals that include meaningful rate increases that ensure they’d continue to be reimbursed at market-competitive rates.”

Brent Estes, a senior vice president at Mount Sinai, said United “has offered us virtually nothing more than the prior contract.”

“Regrettably,” he added, “we are bracing for our physicians to be out of network.”

How might patients be affected?

The situation has been especially stressful and confusing for New Yorkers who are receiving cancer care at Mount Sinai or who had planned to give birth there, according to doctors. Though such patients may be eligible to remain with their doctor without paying more, it has been tough to get clear answers.

One pregnant woman, for instance, received a letter last month from UnitedHealthcare saying that she would still be considered in network at Mount Sinai when it came time to deliver her baby. But the letter, which was provided to The Times by a Mount Sinai employee with the patient’s name redacted, said the in-network coverage was approved for a three-day period in April — apparently corresponding with her due date — and covered only “routine obstetric care” and a vaginal delivery.

The letter said nothing about what would happen if she went into labor early, or needed a C-section. A spokesman for UnitedHealthcare, Cole Manbeck, said that some automated letters sent by the insurance company “may have created a little bit of confusion.” But Mr. Manbeck said United had followed up with phone calls to clarify that the delivery would be covered, no matter the date or method.

Jane Hogan, a 55-year-old writer for a cosmetics company, sees Mount Sinai doctors for chronic migraines and back problems.

She spent one recent morning trying to ensure that a biopsy would be covered under her United health insurance. She called the situation “anxiety inducing” and time-consuming.

Many other hospitals in New York City remain within UnitedHealthcare’s networks, including NewYork-Presbyterian, the city’s largest private hospital system.

Chris Pope, a health care policy analyst at the Manhattan Institute, a conservative think tank, said the insurer probably had the upper hand in negotiations because United patients could just move their care to other health systems, leaving Mount Sinai with far less revenue, he said.

“United can walk away from Sinai, much easier than Sinai can do without United,” he said.