Southern Maine health care provider InterMed PA has joined Community Health Options, a Lewiston-based co-op created in 2013 to offer health insurance plans under the Affordable Care Act.

The nonprofit Community Health Options said in a news release Monday that it entered into a partnership with InterMed to increase the number of choices available to its members.

InterMed is the largest physician-owned primary care practice in Maine, with 81 physicians in Portland, South Portland and Yarmouth, it said.

“InterMed is highly respected and an important source of care for more than 75,000 primary care patients in the community. Together we seek to achieve the triple aim of reducing costs of care while improving health outcomes and improving the patient experience,” Health Options CEO Kevin Lewis said in the release.

InterMed CEO Dan McCormack said he was impressed with the rapid membership growth Community Health Options has experienced in Maine and New Hampshire.

“It was clear from the beginning of our discussions that our interests are aligned with a shared desire to provide high-quality, high-value healthcare for our patients,” he said.