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Strategic Formulary Design in Medicare Part D Plans

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  • Kurt Lavetti
  • Kosali Simon

Abstract

The design of Medicare Part D causes most Medicare beneficiaries to receive fragmented health insurance, whereby prescription drugs and other medical care are covered by separate insurance plans. Fragmentation of insurance plans is potentially inefficient since separate insurers maximize profits over only one component of healthcare spending, despite many complementarities and substitutabilities between types of healthcare. Fragmentation of some plans but not others can also lead to market distortions due to differential adverse selection, as integrated plans may use drug formulary designs to induce enrollment by patients who are profitable under Parts A & B, while stand-alone drug plans have no such incentive. We study whether the design of insurance plans in Medicare Part D reflects these two differences in incentives using data on the universe of Part D plan formularies, drug prices, and Medicare claims data. We find evidence consistent with both hypotheses. Relative to fragmented plans, integrated plans systematically design their drug formularies to encourage enrollment by beneficiaries with medical conditions that are profitable under Parts A & B. However, integrated plans also more generously cover drugs that have the potential to causally reduce medical costs. These large differences in incentives and plan design between integrated and fragmented plans are likely the precursors of substantial differential selection of enrollees, and the basic design of Medicare Part D abets this covert selection.

Suggested Citation

  • Kurt Lavetti & Kosali Simon, 2016. "Strategic Formulary Design in Medicare Part D Plans," NBER Working Papers 22338, National Bureau of Economic Research, Inc.
  • Handle: RePEc:nbr:nberwo:22338
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    Cited by:

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    2. A. A. Withagen-Koster & R. C. Kleef & F. Eijkenaar, 2020. "Incorporating self-reported health measures in risk equalization through constrained regression," The European Journal of Health Economics, Springer;Deutsche Gesellschaft für Gesundheitsökonomie (DGGÖ), vol. 21(4), pages 513-528, June.
    3. David Dranove & Christopher Ody & Amanda Starc, 2021. "A Dose of Managed Care: Controlling Drug Spending in Medicaid," American Economic Journal: Applied Economics, American Economic Association, vol. 13(1), pages 170-197, January.
    4. Michele Fioretti & Hongming Wang, 2019. "Subsidizing Inequality: Performance Pay and Risk Selection in Medicare," Sciences Po Economics Discussion Papers 2019-15, Sciences Po Departement of Economics.
    5. Michael Geruso & Timothy J. Layton, 2017. "Selection in Health Insurance Markets and Its Policy Remedies," Journal of Economic Perspectives, American Economic Association, vol. 31(4), pages 23-50, Fall.
    6. Bergquist, Savannah L. & Layton, Timothy J. & McGuire, Thomas G. & Rose, Sherri, 2019. "Data transformations to improve the performance of health plan payment methods," Journal of Health Economics, Elsevier, vol. 66(C), pages 195-207.
    7. Michael Geruso & Timothy Layton & Daniel Prinz, 2019. "Screening in Contract Design: Evidence from the ACA Health Insurance Exchanges," American Economic Journal: Economic Policy, American Economic Association, vol. 11(2), pages 64-107, May.
    8. Timothy Layton & Alice K. Ndikumana & Mark Shepard, 2017. "Health Plan Payment in Medicaid Managed Care: A Hybrid Model of Regulated Competition," NBER Working Papers 23518, National Bureau of Economic Research, Inc.
    9. Nathan Kettlewell, 2020. "Policy Choice and Product Bundling in a Complicated Health Insurance Market: Do People Get It Right?," Journal of Human Resources, University of Wisconsin Press, vol. 55(2), pages 566-610.
    10. Michele Fioretti & Hongming Wang, 2020. "Performance Pay in Insurance Markets: Evidence from Medicare," Working Papers 2020.03, International Network for Economic Research - INFER.
    11. Martin Andersen, 2017. "Constraints on Formulary Design Under the Affordable Care Act," Health Economics, John Wiley & Sons, Ltd., vol. 26(12), pages 160-178, December.
    12. Savannah L. Bergquist & Timothy J. Layton & Thomas G. McGuire & Sherri Rose, 2018. "Intervening on the Data to Improve the Performance of Health Plan Payment Methods," NBER Working Papers 24491, National Bureau of Economic Research, Inc.
    13. Jonathan Gruber, 2017. "Delivering Public Health Insurance through Private Plan Choice in the United States," Journal of Economic Perspectives, American Economic Association, vol. 31(4), pages 3-22, Fall.
    14. Geruso, Michael & Layton, Timothy J. & McCormack, Grace & Shepard, Mark, 2019. "The Two Margin Problem in Insurance Markets," Working Paper Series rwp19-035, Harvard University, John F. Kennedy School of Government.
    15. Ausmita Ghosh & Kosali Simon & Benjamin D. Sommers, 2017. "The Effect of State Medicaid Expansions on Prescription Drug Use: Evidence from the Affordable Care Act," NBER Working Papers 23044, National Bureau of Economic Research, Inc.
    16. Ghosh, Ausmita & Simon, Kosali & Sommers, Benjamin D., 2019. "The Effect of Health Insurance on Prescription Drug Use Among Low-Income Adults:Evidence from Recent Medicaid Expansions," Journal of Health Economics, Elsevier, vol. 63(C), pages 64-80.

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    More about this item

    JEL classification:

    • I11 - Health, Education, and Welfare - - Health - - - Analysis of Health Care Markets
    • I13 - Health, Education, and Welfare - - Health - - - Health Insurance, Public and Private

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