Out-of-pocket costs for infliximab and its biosimilar for RA under Medicare Part D

Prescribing biosimilar versions of biologic drugs is intended to bring costs down, but Medicare's complex cost-sharing structure makes it difficult to tell whether this goal has been accomplished in this patient population.

Prescribing biosimilar versions of biologic drugs is intended to bring costs down, but Medicare's complex cost-sharing structure makes it difficult to tell whether this goal has been accomplished in this patient population. For example, branded drugs and biologics—but not biosimilars—are discounted during the coverage gap period that is triggered when a beneficiary's total drug costs exceed a designated threshold. That is set to change next year, when biosimilars will receive the same 50% break as biologics, but patients' out-of-pocket responsibilities will still hinge on whether they are treated differently than biologics in terms of pricing and plan cost-sharing requirements. To investigate, researchers considered the first biosimilar for rheumatoid arthritis—infliximab-dyyb—and its index biologic, infliximab. Of 2,547 plans nationwide, only 10% covered the biosimilar; while 96% covered the biologic. Infliximab-dyyb had moderately lower costs over an 8-week prescription period as well as on an annual basis; however, Part D plans all required coinsurance cost-sharing similar to what was required with infliximab. Absent the gap discounts, expected out-of-pocket costs were $5,118 per year for infliximab-dyyb vs. $3,432 per year for infliximab. Even with biosimilar gap discounts starting in 2019, infliximab-dyyb still may not significantly reduce out-of-pocket obligations for Part D beneficiaries due to its steep price and coinsurance cost-sharing similar to infliximab. Rather, the market will require additional policy to address affordability and access to specialty drugs.