Budget impact of adding peginterferon beta-1a to the formulary for the treatment of relapsing forms of multiple sclerosis

BACKGROUND: Peginterferon beta-1a is a new interferon that is dosed every 2 weeks via subcutaneous injection and indicated for the treatment of relapsing forms of multiple sclerosis (MS). OBJECTI VE: To estimate the budget impact of adding peginterferon beta-1a to a managed care formulary in the U.S. METHODS: A model was developed in Microsoft Excel to evaluate the budget impact over a 5-year time horizon of adding peginterferon beta-1a to the current mix of disease-modifying therapies (DMTs) used for the treatment of relapsing forms of MS. The model compared the drug-related and relapse costs of the current mix of treatments with the costs of an estimated treatment mix with peginterferon beta-1a included on a managed care organization (MCO) formulary for an MCO with 1,000,000 covered lives. The number of people with relapsing forms of MS in the MCO was estimated using published prevalence data. Treatment share of peginterferon beta-1a was assumed to increase from 3% in 2014 to 7% in 2018 with this market share taken proportionately by treatment shares from the other interferons. Drugrelated costs included: acquisition costs adjusted by co-payments or coinsurance rates and dispensing fees; administration and monitoring costs for related resource use; and adverse event treatment costs based on resource use for two potential adverse events, influenza-like symptoms and injection site necrosis. Annual relapse treatment costs were estimated using relapse rates from the ADVANCE phase 3 trial placebo group, relative risk reduction of a relapse for each DMT in the treatment mix derived using a mixed-treatment comparison analysis, and the treatment cost for a relapse from a U.S. study. A one-way sensitivity analysis was performed changing key input parameter values. RESULTS: The estimated budget impact of adding peginterferon beta-1a to the formulary was negative for the first 5 years: in 2014, with a treatment share of 3.0%, the estimated budget decrease was 0.07% of the total annual costs for DMT-related and relapse treatment costs and a decrease of $0.005 per member per month (PMPM); in 2018, with a treatment share of 7%, the estimated budget decrease was 0.23% of the total annual costs and a decrease of $0.014 PMPM. Sensitivity analyses showed that the model was most sensitive to the acquisition costs of peginterferon beta-1a. CONCLUSIONS: Under model assumptions for market shares, adding peginterferon beta-1a to the MCO formulary would result in a small decrease in MCO costs for patients with relapsing forms of MS.