DAYTON — Edward and Ginger Seamon of Middletown took pride in the new Atrium Medical Center in Warren County, volunteering there regularly.

But the Seamons — he a retired principal and she a retired teacher — now find themselves in a fix: After Jan. 1, should they need hospitalization, they can’t be admitted at Atrium without paying cost-prohibitive, out-of-network rates.

That’s because Medical Mutual of Ohio said last week it’s terminating its agreement with Premier Health Partners, whose hospitals include Miami Valley and Good Samaritan hospitals, Upper Valley Medical Center and Atrium. Medical Mutual said it won’t accept Premier’s proposed reimbursement rates.

“It’s very ironic that we can’t use it (Atrium),” Ginger Seamon said. She and her husband, who is about to receive a volunteer service award from the hospital, plan to stop volunteering there at year’s end.

The Seamons aren’t alone. Public-sector retirees throughout the Dayton region will be affected if Premier Health Partners is no longer part of Medical Mutual’s network.

In 2010, a Medical Mutual plan is the only option available for State Teachers Retirement System retirees 65 and older not enrolled in Medicare parts A and B, as well as for retirees under 65, STRS spokeswoman Laura Ecklar said. (The Seamons don’t have Medicare part A).

The impact will be felt primarily in retirees’ access to hospitals, not doctors, Ecklar said.

Ecklar couldn’t say how many STRS beneficiaries would be affected by the pending Medical Mutual-Premier rift.

The Ohio Public Employees Retirement System, meanwhile, has 2,393 beneficiaries in the Dayton area that use the Premier hospital network, OPERS spokeswoman Julie Graham-Price said. The majority of them are not Medicare-eligible, meaning they’re under 65 years old.

Beneficiaries of the Ohio Police and Fire Pension Fund are not affected; their benefits are administered by UnitedHealthcare, a fund spokesman said.

Medical Mutual is also the sole third-party administrator for Upper Valley Medical Center’s health plan. The looming rift affects 1,120 employees there.

Medical Mutual members may call (877) 328-6664 for information.

Contact this reporter at (937) 225-7457 or bsutherly@DaytonDailyNews.com.