Background: Three interferon (IFN) beta products are currently available for the treatment of relapsing multiple sclerosis (MS). Each of these agents showed effectiveness in the treatment of MS in the respective randomized, double-blind, placebocontrolled Phase III trials. However, there have been no randomized, double-blind, placebo-controlled trials directly comparing the efficacy and safety of these formulations.
Objective: The objective of this article was to compare the results of available comparative studies with the results of the pivotal Phase III trials of each IFN beta product.
Methods: BIOSIS, Current Contents/Clinical Medicine, and MEDLINE were searched for English-language articles published from 1996 to the present comparing the efficacy and safety of IFN beta formulations in the treatment of MS. Search terms included interferon beta 1a, interferon beta 1b, and multiple sclerosis. Articles or abstracts that reported the results of Phase III trials or studies directly comparing IFN beta formulations in the treatment of relapsing or relapsing-remitting MS were included in the review.
Results: Seven head-to-head studies were identified that directly compared the efficacy of IFN beta products in the treatment of MS. Two of these studies- INCOMIN (Independent Comparison of Interferon) and EVIDENCE (Evidence for Interferon Dose-Effect: European-North American Comparative Efficacy)- found significant differences in clinical efficacy between IFN beta products, whereas the remaining studies showed equal clinical efficacy between products.
Conclusion: Inconsistencies within and between the results of the reviewed studies suggest that clinicians should use caution in interpreting the findings of the INCOMIN and EVIDENCE comparative trials.