Analysis of Proposed Medicare Part B to Part D Shift With Associated Changes in Total Spending and Patient Cost-Sharing for Prescription Drugs

JAMA Intern Med. 2019 Mar 1;179(3):374-380. doi: 10.1001/jamainternmed.2018.6417.


Importance: The US Department of Health and Human Services (HHS) has proposed to reform drug pricing in Medicare Part B, which primarily covers physician-administered drugs and biologic agents. One HHS proposal would shift coverage of certain drugs from Medicare Part B to Part D, which is administered by private prescription drug plans.

Objective: To estimate the association of changes of a shift in Medicare Part B to Part D with total drug spending and patient cost-sharing.

Design, setting, and participants: Retrospective drug cohort study of the 75 brand-name drugs associated with the highest Part B expenditures among fee-for-service Medicare beneficiaries in 2016.

Main outcomes and measures: Estimated total Medicare spending in Part B and Part D; annual out-of-pocket costs in Part B and under the standard 2018 Part D benefit; and proportion of drugs in Part D's protected drug classes (immunosuppressants for prophylaxis of organ transplant rejection, antidepressants, antipsychotics, anticonvulsants, antiretrovirals, and antineoplastics).

Results: At 2018 prices, total Medicare Part B spending for the 75 brand-name drugs with the highest Part B expenditures was estimated to be $21.6 billion annually. Under the proposed policy, total Part D drug spending for these drugs was estimated to range between $17.6 billion and $20.1 billion after rebates, corresponding to a 6.9% to 18.3% decrease in drug spending in Part D compared with Part B. Of the 75 drugs studied, 33 (44.0%) drugs, accounting for $9.5 billion (43.9%) in Part B spending, were in protected Part D classes where plans must cover essentially all drugs. For 67 drugs with available information, the prices for 65 (97.0%) were a median of 45.8% to 59.7% lower in comparator high-income countries than Part B drug prices. Median patient cost-sharing in Part B for all 75 brand-name drugs was $4683 (interquartile range [IQR], $1069-$9282) per year. Shifting Part B drugs to the 2018 standard Part D benefit was projected to decrease out-of-pocket costs by a median of $860 (IQR, -$3884 to $496) among Medicare beneficiaries without Medicaid or Part B supplemental insurance (Medigap). For beneficiaries who would qualify for the low-income subsidy program in Part D, cost-sharing would be lower in Part D than in Part B for all drugs. For beneficiaries with Medigap insurance, estimated Part D out-of-pocket costs exceeded average Medigap premium costs by a median of $1460 for those with Part D coverage and by a median of $1952 for those without Part D coverage.

Conclusions and relevance: Although the HHS proposal to shift certain drugs from Medicare Part B to Part D may reduce total drug spending, it may increase out-of-pocket costs for some Medicare beneficiaries, including those with Medicare supplement insurance. The Department of Health and Human Services should ensure that the proposed reforms benefit both patients and payers.

Publication types

  • Research Support, Non-U.S. Gov't
  • Video-Audio Media

MeSH terms

  • Aged
  • Cost Sharing*
  • Female
  • Humans
  • Male
  • Medicare Part B / economics*
  • Medicare Part D / economics*
  • Prescription Drugs / economics*
  • Retrospective Studies
  • United States


  • Prescription Drugs