HealthPartners says it will drop out of the network next year for UnitedHealthcare Medicare Advantage plans, claiming the nation's largest health insurer has an excessively high rate of coverage denials and frequently delays payment for services used by seniors.

Bloomington-based HealthPartners, one of the largest operators of hospitals and clinics in the Twin Cities, is sending letters this week about the change to roughly 30,000 patients.

The health system says practices at UnitedHealthcare create unnecessary waits and delays for patients that interfere with appropriate care.

"UnitedHealthcare delays and denies approval of payment for our patients' Medicare Advantage claims at a rate unlike any other insurer in our market," the letter says. "At times, this denial rate has been up to 10 times higher than other insurers we work with."

UnitedHealthcare, through a spokesperson, said it offered certain contract terms earlier this year that were sought by HealthPartners, but the health system later walked away from its position. UnitedHealthcare said HealthPartners is now making untrue and outlandish allegations about the insurer denying claims.

The spokesperson also alleged HealthPartners sought a price increase for employer-sponsored Medicare Advantage plans that would make its services more expensive than peer health systems.

"We proposed a contract that provided solutions HealthPartners sought to continue participating in our Medicare Advantage network," UnitedHealthcare said in a statement. "Rather than using the remaining time on our contract to implement these solutions, HealthPartners rescinded its position and is now putting Medicare Advantage patients in the middle of our negotiation, unnecessarily creating stress and fear for them while spreading outlandish, false claims."

HealthPartners will remain in-network through the end of the year, so subscribers don't need to take any action now.

The network change could be a factor, however, for seniors considering their options this fall in the annual open enrollment period for Medicare Advantage coverage. With these Advantage health plans, seniors choose to receive Medicare benefits through a private managed care health insurer.

UnitedHealthcare, however, said there's still time for negotiations.

"Our goal is to utilize the remaining months on our contract to reach an agreement that ensures the people we serve have continued network access to HealthPartners," the insurer said.

UnitedHealthcare and its parent-company, Minnetonka-based UnitedHealth Group, have faced a series of questions over the past year or so about coverage practices and policies. This month, 11 people were arrested outside its Minnetonka headquarters during an event to spotlight coverage denials.

In November, UnitedHealth Group was hit by a class-action lawsuit claiming the company used a faulty artificial intelligence algorithm to wrongly block coverage for certain Medicare patients. In July 2023, the U.S. Department of Labor sued a company subsidiary over allegations of wrongful coverage decisions.

HealthPartners is Minnesota's second largest nonprofit group. Its operations include one of the state's largest health insurance companies, a division competing against UnitedHealthcare in the Medicare Advantage market.

The network change next year will apply to care at HealthPartners and Park Nicollet clinics as well as the nonprofit group's hospitals, including Regions in St. Paul, Methodist in St. Louis Park and Lakeview in Stillwater.

"It's unusual for us to leave a health plan network," HealthPartners says in its patient letter. "Unfortunately, after a year of negotiations, we've determined that we can no longer participate in the UnitedHealthcare Medicare Advantage network."

Last summer, HealthPartners announced it would drop in 2024 from the network for Medicare Advantage plans from Humana, a Kentucky-based insurer. In that instance, the nonprofit did not mention concerns about denial rates in letters that were sent to about 13,000 patients.

UnitedHealthcare is the nation's largest Medicare Advantage health insurer. The company has grown its market share in Minnesota since entering the market for seniors here in 2019. That year, Humana also gained Medicare Advantage market share in Minnesota, amid membership declines at HealthPartners and two other nonprofit insurers.

Almost all doctors and hospitals are part of original Medicare, but Medicare Advantage plans have limited networks of doctors and hospitals that agree to provide care for the lowest out-of-pocket cost to seniors. These network rules effectively limit choices if enrollees can't afford the higher fees with out-of-network care.

Medicare open enrollment runs Oct. 15 through Dec. 7. That's the best time, according to HealthPartners, for people with individual Medicare Advantage coverage to consider options.

The health system says people with UnitedHealthcare Medicare Advantage provided by a former employer should discuss options with their employer or UnitedHealthcare.