A network of independent doctors in Marin County and southern Sonoma County is making a big push farther north, recruiting scores of doctors in Sebastopol, Healdsburg and Santa Rosa.

The expansion could offer the county's struggling community hospitals and many local doctors fighting to keep their private practices afloat the chance to become part of a medical provider network able to compete with health care giants Kaiser Permanente and Sutter Health.

For tens of thousands of HMO patients in Sonoma County, it means the opportunity to choose from hundreds of primary care physicians and specialists in two counties.

On Friday, the Marin-Sonoma Individual Practice Association, or IPA, signed an agreement with Annadel Medical Group, which is made up of 28 doctors on staff at Santa Rosa Memorial.

Participation in the IPA means that Annadel doctors will accept HMO patients who are enrolled in the Marin-Sonoma IPA. The IPA will also take over the task of negotiating contracts with HMO plans, securing a prepaid contract for physician services.

"This alliance will prove an important first step in what we hope will be a continually growing network of physicians and health care providers who share a common long-term vision," said Todd Salnas, chief operating officer of St. Joseph Health System-Sonoma County.

Evan Rayner, CEO of Healdsburg District Hospital, said Friday that 11 independent primary care doctors with ties to the hospital have also recently become members of the IPA. Similar talks are under way between the IPA and local physicians throughout the county.

The Marin-Sonoma IPA is discussing a possible "integration" with the much smaller Sebastopol-based IPA, said Dr. Richard Powers, a west county family physician with strong ties to Palm Drive Hospital.

"Palm Drive needs to be part of a larger marketing and contracting group to survive," said Powers, a former president of the Sonoma County Medical Association.

Before the recent additions, the IPA boasted 100 physician members in Sonoma Valley and Petaluma. The network now has 250 physicians in the county, including 67 primary care and 194 specialists, said Joel Criste, Marin-Sonoma IPA's CEO. The association has 300 doctors in Marin County.

Criste said the IPA could grow to about 500 doctors by the end of the year.

Formerly known as the Marin IPA, the network will also promote and market local doctors, their services and specialties and their affiliated hospitals.

"They can't compete with Sutter or Kaiser if they're just this one little hospital," said Powers. "They need to be part of a larger organization."

In addition to handling medical service contracts for its doctors, the Marin-Sonoma group offers continuing medical education courses, patient health education and professional support for adopting electronic health records.

"We've already been in Sonoma County for a while and considered a name change before," said Marcy Norenius, the organization's director of special projects. "The reason we're looking at moving north is to help the private practice physician up there continue to practice independently and to give patients up there in Sonoma County better access to a larger physician network."

The expansion into Sonoma County comes as private doctors locally and across the country are struggling to keep practices open. Medicare reimbursements, which often drive private insurance reimbursements, have not kept up with medical inflation for the past 14 years, said Dr. Peter Bretan, a Novato urologist and president of the Marin Medical Society.

Last year, the Marin IPA and Marin General Hospital formed a nonprofit foundation called Prima Medical Foundation, which contracts with the Prima Medical Group, a for-profit physicians group of about 48 physicians -- six of them in Sonoma Valley.

The foundation was formed as a way of recruiting and retaining primary care physicians and specialty physicians for communities feeling the competitive squeeze. One of the corporate sponsors of the Prima Medical Foundation is Sonoma Valley Hospital.

The six Sonoma doctors are also members of the new Marin-Sonoma IPA.

The IPA network bands together medical groups, large and small hospitals and private doctors in alliances that are a wave of the future under President Barack Obama's Affordable Care Act, which calls on health care providers to provide more efficient patient care.

In late March, the federal government released rules governing the creation of Accountable Care Organizations, health care networks made up of doctors, hospitals and other medical providers.

These organizations would share the responsibility of keeping patients healthier, helping them avoid costly hospital stays and treatments. Doctors, hospitals and other providers would share these savings. Local health care professionals are only now beginning to digest the new rules.

Some observers said the Marin-Sonoma IPA may be the first step toward the formation of an accountable care organization. But Marin-Sonoma IPA's Norenius said it's too early to make such a claim.

"We're looking at that," she said, "and trying to decide what the best way is to meet those requirements and that need."

You can reach Staff Writer Martin Espinoza at 521-5213 or martin.espinoza@pressdemocrat.com.