The state has selected six organizations to oversee health care for some of the neediest adults in Massachusetts, as it works to streamline coverage for about 110,000 people who qualify for both Medicare and Medicaid.

The program is aimed at saving money and lessening the confusion for doctors and patients caused by the two programs sharing responsibility for bills. Many dually eligible people have complex and costly health needs, including mental illnesses, developmental disabilities, or drug and alcohol addictions.

The groups chosen as “integrated care organizations” already are established insurers in Massachusetts or have experience managing health coverage for large groups of patients. They must complete a state readiness review before the program begins enrolling people in April.

In most counties, dually eligible people can choose between several organizations authorized to manage their coverage. If they don’t select an organization, they will be assigned to one by the state, unless they opt out of the program entirely.

Network Health will serve the entire state and is the only organization available in Dukes and Nantucket counties. The other organizations approved for certain counties are Blue Cross Blue Shield of Massachusetts, Boston Medical Center HealthNet Plan, Commonwealth Care Alliance, Fallon Total Care, and Neighborhood Health Plan.

The Fallon group is a partnership between Fallon Community Health Plan and Magellan Health Services, Inc., a Connecticut-based publicly-traded firm that, among other things, provides Medicaid pharmacy benefits in two dozen states.