Estimating Medicare advantage lock-in provisions impact on vulnerable Medicare beneficiaries.

Beginning January 2006, Medicare beneficiaries will have limited ability to change health plans. We examine the Medicare managed care enrollment and disenrollment behavior of traditionally vulnerable beneficiaries from 1999-2001 to estimate the potential impact of the new enrollment restrictions. Findings that several such groups were more likely to make multiple health plan elections, leave their managed care plan midyear, and/or have higher...