Impact of Medicare Part D on access to and cost sharing for specialty biologic medications for beneficiaries with rheumatoid arthritis

Arthritis Rheum. 2009 Jun 15;61(6):745-54. doi: 10.1002/art.24560.


Objective: Many worry that the use of specialty tiering for biologic disease-modifying antirheumatic drugs (DMARDs) by Medicare Part D plans imposes a heavy financial burden on beneficiaries with rheumatoid arthritis (RA). To date, no one has examined the cost-sharing structures for biologic DMARDs in Part D plans or the resulting cost burden for patients.

Methods: We followed 14,929 vulnerable, low-income patients with RA who were enrolled in the Medicare Replacement Drug Demonstration (MRDD) in 2005. As the MRDD population transitioned into Part D in 2006, we examined correlates of Part D enrollment and compared the cost-sharing provisions for biologic DMARDs in the Medicare Advantage and stand-alone plans. We simulated the out-of-pocket costs of beneficiaries under 3 cost-sharing scenarios.

Results: Eighty-one percent of MRDD beneficiaries with RA enrolled in Part D. Enrollment predictors were female sex (odds ratio [OR] 1.48, 95% confidence interval [95% CI] 1.32-1.67), prior MRDD benefit use (OR 2.29, 95% CI 2.04-2.58), other self-reported drug coverage (OR 1.53, 95% CI 1.36-1.71), and receiving an MRDD subsidy (OR 2.00, 95% CI 1.74-2.30). Compared with stand-alone plans, Medicare Advantage plans had lower deductibles, lower premiums, and fewer prior authorization, step therapy, and quantity limit restrictions. However, approximately 75% of all plans used coinsurance as the preferred form of cost sharing. Out-of-pocket costs exceeded $4,000 annually in all cost-sharing scenarios.

Conclusion: Most MRDD beneficiaries with RA enrolled in Part D. Although plans assume some costs for biologic DMARDs, the majority of costs are shifted to beneficiaries and to Medicare. Such cost shifting may place these medications out of the beneficiary's financial reach and expose Medicare to high financial liability.

MeSH terms

  • Aged
  • Antibodies, Monoclonal / economics*
  • Antibodies, Monoclonal / therapeutic use
  • Antirheumatic Agents / economics*
  • Antirheumatic Agents / therapeutic use
  • Arthritis, Rheumatoid / drug therapy
  • Arthritis, Rheumatoid / economics*
  • Cost Sharing*
  • Female
  • Health Services Accessibility / economics*
  • Health Services Accessibility / legislation & jurisprudence
  • Humans
  • Male
  • Medicare Part D*
  • United States


  • Antibodies, Monoclonal
  • Antirheumatic Agents