ST. LOUIS — UnitedHealthcare notified more physicians that they will be removed from the company's Medicare Advantage plan on Sept. 1, which may mean thousands of Missourians will have to switch doctors.

it is the second round of cuts to UnitedHealthcare's Medicare Advantage physician ranks, the St. Louis Post-Dispatch reported. UnitedHealthcare is the largest carrier of Medicare Advantage plans for seniors and has about 95,000 plan members in Missouri.

Cardiologist Joseph Craft III, president of the St. Louis Metropolitan Medical Society, said the decision will affect thousands of patients in the St. Louis area alone.

UnitedHealthcare terminated nearly 100 Missouri doctors from the Medicare Advantage plan in April and said it plans to cut 5 percent to 7 percent of the more than 10,000 physicians in Missouri this year. The company told the Post-Dispatch in an email that the cuts affected less than 10 percent of the state's physicians, which would translate to fewer than 1,000 physicians. UnitedHealthcare does not expect to make any more changes to its size in Missouri this year.

The newspaper said that much of the latest cut seems target dermatologists, ophthalmologists, gastroenterologists and orthopedic surgeons.

Dr. George Hruza of Chesterfield, president-elect of the American Society for Dermatologic Surgery, received the network termination on June 2. He said that at least 36 other dermatologists have been terminated — nearly half of the skin specialists in the St. Louis region.

"This area has a lot of farmers, so a lot of people who have sun damage — these patients are now asked to find another doctor," Hruza said.

UnitedHealthcare said the main factors for the change were the health industry's move toward quality over quantity and a closer collaboration between insurers and doctors. The provider said that with a smaller group of doctors, patient data could be shared better, too.

"We are working to make transitions to new doctors as smooth as possible and will do all that we can to prevent interruptions in care," UnitedHealthcare spokeswoman Jessica Kostner said.

But Craft said, "The relationships (doctors) have with their patients is being disrupted arbitrarily, mid-contract term, with no explanation. It's not reasonable. It's not fair to patients to do that."