The new Medicare Part D prescription drug benefit: an estimation of its effect on prescription drug costs in a Medicare population with atrial fibrillation.

OBJECTIVES: To compare prescription drug cost savings under the most commonly selected Medicare Part D prescription plan in 2006 with savings under the Medicare standard benefit and with drug costs assuming no coverage in an elderly cohort of patients.
DESIGN: Inception cohort study.
SETTING: An academic medical center. PARTICIPANTS: Four hundred seventy-two patients aged 65 and older who were followed as part of a larger study assessing stroke prevention in patients with atrial fibrillation. MEASUREMENTS: Prescription drug expenditures were calculated for each patient in the cohort under three conditions: the 2006 AARP-endorsed prescription drug plan, the Medicare standard benefit, and no prescription drug coverage.
RESULTS: Total prescriptions drug costs were lower under the AARP plan, yet patients paid a similar percentage of total costs under the AARP plan and the Medicare standard benefit. Using different cost assessments, 27% to 46% of patients entered the "doughnut hole" in the AARP plan, and 3% to 11% emerged to receive catastrophic coverage.
CONCLUSION: Both the AARP-sponsored and standard Medicare Part D prescription drug benefit programs offer significant savings to enrollees. A greater savings is achieved under the private AARP drug insurance plan, largely due to greater discounts reflected in the negotiated drug prices. A substantial portion of enrollees enter but do not emerge from the coverage gap.