More than 135,000 high-cost Illinois patients who are eligible for both Medicare and Medicaid will be assigned to a managed care health plan by early next year, if they don't opt out of a new program to coordinate their care.

The initiative is a partnership between Illinois and the federal Centers for Medicare and Medicaid Services.

Illinois is the fourth state to get approval for such a demonstration project, aimed at providing better care at lower costs for a group of patients known as "dual eligibles." The federal agency announced its approval Friday.

Dual eligibles account for a high proportion of spending in Medicaid. In 2010, for example, they made up about 9% of the population and 27% of the costs of the program.