The vast majority of Medicare Part D beneficiaries still don't choose the cheapest plans that meet their medication needs.

When the Medicare Part D prescription drug benefit began in 2006, a primary concern for some policy makers was whether seniors would be able to make smart choices from among the dozens of competing plans. Using 2009 Part D data, we found that only 5.2 percent of beneficiaries chose the cheapest plan. Nationwide, beneficiaries on average spent $368 more annually than they would have spent had they purchased the cheapest plan available in their region, given their medication needs. More than a fifth of beneficiaries spent at least $500 a year more than they needed to. Beneficiaries often overprotected themselves by paying higher premiums for plan features that they did not need, such as generic drug coverage in the coverage gap. Our findings suggest that beneficiaries need more targeted assistance from the government to help them choose plans, such as customized communications about the most cost-effective plans that would cover their medication needs.