Importance of benefit-to-risk assessment for disease-modifying drugs used to treat MS.

Interferon (IFN) beta has been shown to be an effective therapy in pivotal studies of multiple sclerosis (MS), with differences in outcomes based on dose and/or frequency of administration. Glatiramer acetate (GA) has also shown to have an effect on relapses and magnetic resonance imaging measures, but not on disability. All products are associated with adverse events, and utilisation of a specific therapy needs to consider benefit in relation to risk. Evidence-based medicine provides a means of assessing benefit and risk in the context of the number of patients one needs to treat to obtain benefit (NNT) compared with the number needed to treat for an adverse outcome (NNH). Efficacy and safety data are presented from IFN beta-1a (Rebif) clinical trials, including relevant NNT and NNH values, to allow assessment of the overall benefit-to-risk ratio compared with placebo. Additional comparisons are made with published data for other IFN products and GA. The indirect comparative information reviewed demonstrates that IFN appears to have a better benefit- to-risk ratio than GA. Indirect comparisons suggest better efficacy of thrice weekly (tiw) IFN beta-1a compared with alternate-day IFN beta-1b, but no direct comparative data are available. Direct comparative data show that IFN beta-1a at a dose of 44 mcg tiw has a favourable benefit-to-risk ratio compared with both 22 mcg tiw and 30 mcg once weekly, suggesting that 44 mcg tiw currently has the best benefit- to-risk ratio for the treatment of relapsing MS.