OBJECTIVES:Our study assessed trends in price, market share, and spending of all self-administered multiple sclerosis (MS) disease-modifying specialty medications in Medicare Part D from 2006-2016.

METHODS:Using Medicare Part D claims data, we extracted claims for self-administered MS disease-modifying specialty medications in 2006-2016. For each medication and year, we calculated:1) annual cost of treatment, based on Medicare Part D gross drug cost data and the recommended dosing regimens approved by the FDA;2) market share, defined as the proportion of treatment year equivalents accounted by every drug; and 3) total spending by year per 1,000 Medicare beneficiaries. We further quantified the contribution of Medicare payments, out-of-pocket costs, low-income cost-sharing (LICS)subsidy, coverage gap discounts, and other payments toward total spending.

RESULTS:Despite growth of therapeutic options, annual cost of treatment more than quadrupled (2006-2016) from $18,660 to $75,847. Trends in annual costs of treatment with each agent increased in parallel and at very similar rates every year. For instance, annual cost of treatment with Copaxone^® increased from $17,924 in 2006 to $36,937 in 2010 to $73,682 in 2016. Similarly, treatment with Avonex^® costed $18,563 in 2006, $35,836 in 2010 and $74,958 in 2016. Throughout the study period, Copaxone^® had the highest market share, followed by Avonex^® and Tecfidera^®.

Total spending per 1,000 beneficiaries increased by more than 10-fold, from $7,872 in 2006 to $79,411 in 2016. In 2016, Medicare payments accounted for 84.04% of total spending, LICS for 6.19%, out-of-pocket costs for 3.37%, manufacturer coverage gap discounts for 1.74%, and other payments for 4.67%.

CONCLUSIONS:Annual costs of treatment and drug spending of self-administered MS disease-modifying medications drastically increased over a decade despite the growth of therapeutic options. Increased competition in the specialty drug market does not necessarily translate into price declines. Policies to cap year-over-year inflation in the costs of existing products must be considered.