Long-term cost effectiveness of interferon-β-1a in the treatment of relapsing-remitting multiple sclerosis: An econometric model

Objective: To evaluate the cost effectiveness of subcutaneous interferon-β-1a (IFNβ-1a) 44μg three times weekly in relapsing-remitting multiple sclerosis (RRMS) using an econometric model. Methods: Data on RRMS patients treated with IFNβ-1a 22 or 44μg subcutaneously three times weekly or placebo for up to 4 years were obtained from the Prevention of Relapses and disability by Interferon-β-1a Subcutaneously in Multiple Sclerosis (PRISMS) study. The area under the Expanded Disability Status Scale (EDSS) score-time curve was used as a measure of disability and the effectiveness of therapy was expressed as EDSS-months of disability prevented. Costs were calculated for the UK and France, and results were projected to 10 and 20 years using a time series regression model. Results: Over 10 years, treatment with IFNβ-1a 44μg subcutaneously three times weekly prevented 121 EDSS-months of additional disability at a cost of Euros (€)732 each (year of costing 2000). Over 20 years, 321 EDSS-months were saved at a cost of €359 per month (year of costing 2000). Conclusion: This analysis indicated that IFNβ-1a 44μg subcutaneously three times weekly is cost effective in RRMS and that treatment becomes increasingly cost effective over time.