Federal and Individual Spending on the 10 Costliest Medications in Medicare Part D from 2011 to 2015.

Access to prescription medications is critical as the U.S. population ages. Escalating drug costs have garnered mounting attention from the public with increasing federal scrutiny. The Medicare Part D program will increasingly be relied upon to support the health of our nation's older people. We reviewed the publically available Medicare Part D usage data from 2011 to 2015 to quantify the cost of the 10 costliest medications for Part D, evaluated the number of beneficiaries treated with these medications, and measured beneficiaries' out-of-pocket costs. We observed over the analysis period, an increase in spending for these medications, a reduction in number of patients that received them, with increased out-of-pocket costs for the patient. In 2015 U.S. dollars, the amount Medicare Part D spent on the 10 costliest medications increased from $21.5 billion in 2011 to $28.4 billion in 2015-a 32% increase. The number of beneficiaries who received 1 of the 10 costliest medications fell from 12,913,003 in 2011 to 8,818,471-a 32% drop, with an average annual decrease of 7.9%. Out of pocket spending by patients that use these medications increased over the study period. For beneficiaries without the low-income subsidy, the average out-of-pocket cost share for 1 of the 10 costliest medications increased from $375 in 2011 to $1,366 in 2015-a 264% increase overall and an average 66% increase per year. Specialty medications are a growing portion of the costliest medications. As medication costs continue to escalate, and specialty medications become more common, the U.S. will be increasingly challenged with devising mechanisms to access sustainable, affordable medications for all older adults.