Trends in Prices, Market Share, and Spending on Self-administered Disease-Modifying Therapies for Multiple Sclerosis in Medicare Part D.

Importance: Before 2009, only 4 self-administered disease-modifying therapies (DMTs) were approved for the treatment of multiple sclerosis (MS). Since then, 7 new agents have entered the market.

Objective: To assess trends in prices, market share, and spending on self-administered DMTs for MS in Medicare Part D from 2006 through 2016.

Design, Setting, and Participants: This cohort study used claims data from 2006 through 2016 from a 5% random sample of Medicare beneficiaries (a mean of 2.8 million Medicare beneficiaries per year). All prescription claims for self-administered DMTs for MS (glatiramer acetate, interferon beta-1a, interferon beta-1b, fingolimod hydrochloride, teriflunomide, dimethyl fumarate, and peginterferon beta-1a) were extracted throughout the study period.

Main Outcomes and Measures: The main outcomes were the annual cost of treatment with each medication, based on Medicare Part D prescription claims gross costs and US Food and Drug Administration-approved recommended dosing; market share of each medication, defined as the proportion of pharmaceutical spending accounted by every drug; and pharmaceutical spending per 1000 Medicare beneficiaries for all drugs. The relative contributions of Medicare Part D Plans' payments, Medicare catastrophic coverage payments, low-income cost-sharing subsidies, patients' out-of-pocket costs, manufacturers' coverage gap discounts, and other payments toward pharmaceutical spending were further quantified.

Results: Annual costs of treatment with self-administered DMTs for MS more than quadrupled from 2006 to 2016, from a mean (SD) of $18 660 ($1177) to $75 847 ($16 956) and at a mean rate of 12.8% every year. Brand-name glatiramers accounted for the largest market share across the study period, ranging between $25 552 of $79 411 per 1000 Medicare beneficiaries (32.2%) and $10 342 of $21 365 per 1000 Medicare beneficiaries (48.4%). Platform therapies experienced a substantial drop from 2006 to 2016 in favor of newer therapies, with decreases in the market shares of brand-name glatiramers (per 1000 Medicare beneficiaries: $2861 of $7794 [36.7%] to $25 552 of $79 411 [32.2%]), interferon beta-1a (30 µg; per 1000 Medicare beneficiaries: $2521 of $7794 [32.3%] to $11 298 of $79 411 [14.2%]), interferon beta-1b (Betaseron; per 1000 Medicare beneficiaries: $1460 of $7794 [18.7%] to $3588 of $79 411 [4.5%]), and interferon beta-1a (8.8/22/44 µg; per 1000 Medicare beneficiaries: $951 of $7794 [12.2%] to $6588 of $79 411 [8.3%]) and increases in fingolimod (to $6311 of $79 411 per 1000 Medicare beneficiaries [7.9%]), teriflunomide (to $7177 of $79 411 per 1000 Medicare beneficiaries [9.0%]), and dimethyl fumarate (to $15 262 of $79 411 per 1000 Medicare beneficiaries [19.2%]). Throughout the study period, pharmaceutical spending per 1000 beneficiaries increased 10.2-fold (from $7794 to $79 411), and out-of-pocket patient spending per 1000 beneficiaries increased 7.2-fold (from $372 to $2673). The relative contribution of federal payments toward pharmaceutical spending increased from $5335 of $7794 (68.5%) to $58 620 to $79 411 (73.8%).

Conclusions and Relevance: Per this analysis, prices of self-administered DMTs for MS increased dramatically between 2006 and 2016. This resulted in a 7.2-fold increase in patient out-of-pocket costs.