A new study in the Archives of Internal Medicine led by Christopher Millett, a 2008–09 Commonwealth Fund Harkness Fellow, examined whether the Medicare Part D prescription drug benefit has reduced out-of-pocket drug costs for seniors and other beneficiaries. The authors found that beneficiaries' mean annual out-of-pocket expenditures on medications decreased by 32 percent, from $1,011 to $691, in the year after Part D was implemented. However, the researchers also noted a 32 percent reduction in spending among beneficiaries who did not enroll in a Part D plan. This decrease may be attributable to the greater availability and use of generic drugs and the introduction of discount prices by large supermarket chains, among other factors.