The Government Accountability Office (GAO) recently released a report on Medicare Part D which found that nearly 90 percent of mid-year changes to the plan were formulary enhancements.

Formulary enhancements can add a drug to the formulary or remove or loosen restrictions on a drug. Such enhacements accounted for 87.4 percent of formulary changes in 2008 and 88.6 percent in 2009. Negative changes, such as removing a drug from a formulary, accounted for 12.6 percent of changes in 2008 and 11.4 percent in 2009. Additionally, in 2008 about 5 percent of beneficiaries (over 1.1 million beneficiaries) filled a prescription for a drug that was later affected by a negative mid-year change.

Pharmaceutical Care Management Association (PCMA) President and CEO Mark Merritt said of the GAO report, "While experts agree that pharmacy benefit managers (PBMs) help Part D come in under budget each year, GAO's new report provides fresh evidence that the Medicare drug benefit also expands access to new medications."