Medicare and Medicaid managed care: a tale of two trajectories.

Two decades of efforts to promote managed care models in Medicare and Medicaid have resulted in vastly different experiences as measured by enrollment, plan participation, and ability to achieve the goals of public policy-makers. The Medicare Modernization Act of 2003 introduced a major transformation to engage and retain private health plans. It is useful for plan administrators to consider why the trajectories for the programs have been so divergent and to assess prospects for success in the Medicare Advantage initiative.