Trends in coverage for disease- modifying therapies for multiple sclerosis in medicare part D

The high cost of multiple sclerosis (MS) disease-modifying therapies can negatively affect access for patients through increased payer restrictions and higher out-of-pocket spending. Our objective was to describe changes in pharmacy benefit coverage and cost-sharing amounts for MS disease-modifying therapies in the Medicare Part D program, using enrollment-weighted Prescription Drug Plan Formulary files for the period 2007-16. Among therapies available throughout the study period, the rate of prior authorization use increased from 61-66 percent of plans to 84-90 percent. The share of plans with at least one therapy available without limitations declined from 39 percent to 17 percent. The projected cumulative out-of-pocket spending for 2019 was $6,894. The therapy with the highest out-of-pocket spending was generic glatiramer acetate. Policy makers need to consider both access restrictions and a growing costsharing burden as potential consequences of high and rising drug prices for people with MS.