Use and Spending for Biologic Disease-Modifying Antirheumatic Drugs for Rheumatoid Arthritis Among US Medicare...

Biologic therapies have assumed an important role in treating rheumatoid arthritis (RA). We sought to investigate use, spending, and patient cost-sharing for Medicare beneficiaries using biologic drugs for RA, comparing patients exposed to minimal cost-sharing because of a Part D low-income subsidy (LIS) to those facing substantial out-of-pocket costs (OOP).

We performed a retrospective, nationwide study using 2009 Medicare claims for a 5% random sample of beneficiaries with RA who had at least 1 RA drug dispensed. We analyzed biologic drug utilization and costs across the Part B (medical benefit) and Part D (pharmacy benefit) programs by LIS status using multinomial regression. We also projected OOP costs as the Affordable Care Act (ACA) mandates closure of the Part D coverage gap by 2020.

Among 6,932 beneficiaries, 1,812 (26.1%) received a biologic drug. LIS beneficiaries were significantly more likely to obtain Part D home-administered biologics (relative risk ratio [RRR] 2.98, 95% confidence interval [95% CI] 2.50-3.56), while non-LIS beneficiaries were less likely to receive Part D biologic agents (RRR 0.58, 95% CI 0.48-0.69). OOP costs in Part D were lower, as expected, for LIS beneficiaries ($72 versus $3,751 per year for non-LIS). Non-LIS beneficiaries had lower costs for Part B facility-administered biologic agents (range $0-$2,584) than for Part D home-administered biologic agents. ACA reforms will narrow OOP differences between Part D and B for non-LIS beneficiaries.

In contrast to LIS beneficiaries who receive mostly Part D home-administered biologic DMARDs, nonsubsidized beneficiaries have significant cost-based incentives to obtain facility-administered biologic DMARDs through Part B. The ACA will result in only slightly lower costs for Part D biologic drugs for these beneficiaries.