Long-term cost-effectiveness model of interferon beta-1b in the early treatment of multiple sclerosis in the United States

BACKGROUND: Multiple sclerosis (MS) is a potentially debilitating autoimmune disease that affects the brain and spinal cord. Disease-modifying therapies have been shown to slow disease progression but were not believed to prolong the survival of patients with MS. The recent 21-Year Long-Term Follow-Up (21Y-LTF) study found a significant survival advantage for patients receiving early treatment with interferon beta (IFNβ)-1b compared with placebo (no early treatment).

OBJECTIVES: The aim of this study was to conduct cost-effectiveness analyses estimating the long-term benefit of early treatment with IFNβ-1b among MS patients from a US societal perspective.

METHODS: A Markov model was developed to simulate the experience of patients with MS from the 21Y-LTF study over a lifetime. Patients were randomized to receive either IFNβ-1b or placebo for up to 5 years and then receive a variety of MS treatments (including no treatment) thereafter. Survival data reported from the 21Y-LTF study were incorporated into the model. The model assumes that patients' MS was managed in similar ways for both groups during the uncontrolled phase of the 21Y-LTF study (ie, survival difference between the 2 groups is the result of early use of IFNβ-1b). Health outcomes were life-years and quality-adjusted life-years (QALYs). Costs included treatments, direct disease management, informal care, and lost productivities and were reported in 2011 US dollars.

RESULTS: In the modeled placebo group, the median age at death was predicted to be 63.7 years, and the median survival time from disease onset was 36.7 years. Early treatment with IFNβ-1b reduced the lost health benefits by 2.8 life-years and 1.9 QALYs, respectively, after discounting. Total discounted cost for IFNβ-1b-treated patients was $86,223 higher than that of patients receiving placebo. The incremental cost-effectiveness ratio was $46,357 per QALY gained and $30,967 per life-year gained. Sensitivity analyses indicate the robustness of the model's results.

CONCLUSIONS: Treatment with IFNβ-1b during the earlier disease phase of patients with MS significantly increased patient life-years and QALYs. IFNβ-1b is likely to be a cost-effective intervention for MS.