To estimate the budget impact of adding delayed-release dimethyl fumarate to a managed care
formulary in the United States (US).
Delayed-release dimethyl fumarate is a new oral drug indicated for the treatment of relapsing forms of multiple sclerosis (MS).
A model was developed in Microsoft Excel to evaluate the budget impact over a 5-year time horizon of adding delayed-release dimethyl fumarate to the current mix of disease-modifying therapies (DMTs) for the treatment of relapsing forms of MS (Figure 1). The model compared the drug-related costs of the current mix of treatments with the costs of an estimated treatment mix with delayed-release dimethyl fumarate included on an MCO formulary for
an MCO with 1,000,000 covered lives. Based on an estimated prevalence of MS in the US of 0.21%1 and an estimated 60% of those with relapsing forms of MS,2 2,100 people were estimated to have a diagnosis of MS, and 1,260 of those were estimated to be living with relapsing forms of MS in any given year. Treatment share of delayed-release dimethyl fumarate was assumed to increase from 10% in 2013 to 25% in 2017, with this treatment share taken proportionately by treatment shares from all the other DMTs (Table 1). Drug costs included acquisition costs adjusted by copayments or coinsurance rates and dispensing fees, as well as administration and monitoring costs based on estimated resource use and US unit costs (Table 2). Annual relapse treatment costs were estimated using the following: Relapse rates from the delayed-release dimethyl fumarate phase 3 trial placebo groups, relative risk reduction of a relapse for each DMT in the treatment mix derived using a mixed-treatment comparison analysis 4,5 (Table 3), and average treatment cost for a relapse from Kobelt and colleagues6 infl ated to 2013 US dollars ($2,117). A one-way sensitivity analysis was performed changing key input parameter values.
The estimated budget impact of adding delayed-release dimethyl fumarate to the formulary was negative for the fi rst 5 years. In 2014, with a treatment share of 13.0%, the estimated budget decrease was 0.10% of the total annual costs for DMT-related and relapse treatment costs and a decrease of $0.006 per member per month (PMPM). In 2017, with a treatment share of 25.0%, the estimated budget decrease was also 0.10% of the total annual costs and a decrease of $0.007 PMPM (Table 4). Sensitivity analyses showed that the model was most sensitive to the acquisition costs of delayedrelease dimethyl fumarate (Figure 2).
Under model assumptions for treatment shares, adding delayed-release dimethyl fumarate to the MCO formulary would result in a small decrease in MCO costs for patients with relapsing forms of MS.