Doctors with the Marin Sonoma Individual Practicce Association are partnering with Health Net to offer an alternative Medicare plan to Sonoma County seniors.

Many faced losing their Medicare Advantage coverage because of a recent deal between UnitedHealthcare and Sutter Health that steered care to Sutter doctors. In 2012, UnitedHealthcare will instead offer two plans, including a zero-premium plan that does not require low-income eligibility but requires beneficiaries to choose from a list of Sutter Health-affiliated providers.

The arrangement with Health Net provides for "a choice of physicians and hospitals throughout Sonoma County," said Joel Criste, chief executive of the Marin Sonoma IPA.

UnitedHealthcare representatives reject the idea that their new plan limits beneficiaries' choice of doctors. A company spokeswoman said the new plan offers cost-savings and access to comprehensive care through Sutter Health's extensive hospital and physician network in Sonoma County, as well as through a broader physician network that includes Annadel Medical Group, Northern California Medical Associates and other contracted physicians. The network extends into the city of Sonoma.

The IPA, a health care system with roots in Marin County, has been making significant inroads into Sonoma County, forming partnerships and alliances with Sonoma County medical groups and facilities.

IPA representatives say the Medicare Advantage plan offered by Health Net will allow seniors to maintain their local doctors and to use non-Sutter community hospitals, including Sonoma Valley Hospital, Santa Rosa Memorial, Petaluma Valley Hospital, Palm Drive Hospital and Healdsburg District Hospital.