Comparing patient OOP spending for specialty drugs in medicare Part D and employer-sponsored insurance

OBJECTIVES: Per capita spending on specialty drugs increased 55% between 2014 and 2018. Individuals aged 55 to 75 years using specialty drugs make the transition from employer-sponsored insurance (ESI) to Medicare Part D coverage. We compared out-of-pocket (OOP) spending across ESI, Medicare fee-for-service (FFS), and Medicare Advantage (MA) prescription drug plans to examine the impact of benefit design on OOP spending. STUDY DESIGN: Analyses consisted of Truven MarketScan and Medicare Part D prescription drug claims from 2013 to 2017 for individuals enrolled in ESI, FFS, and MA drug plans taking at least 1 drug among the top 4 specialty drug classes: rheumatoid arthritis (RA), multiple sclerosis (MS), cancer, and hepatitis C. METHODS: Multivariate regression analyses with fixed effects were used to assess whether there are differences in OOP spending by insurance type and the impact of benefit design differences. A secondary outcome was drug choice within a therapeutic class. RESULTS: There were small differences in drug choice between Medicare and ESI but significant differences in OOP spending. Monthly OOP spending for ESI relative to FFS was $108 less for RA drugs, $288 less for MS drugs, $504 less for cancer drugs, and $1437 less for hepatitis C drugs. Spending was slightly greater for beneficiaries in MA plans compared with FFS. Higher Medicare spending was driven by gaps in coverage in the Part D benefit phases because beneficiaries pay a percentage of list price. CONCLUSIONS: OOP spending was substantially higher for Medicare enrollees compared with ESI enrollees as a result of the Part D benefit structure.