Therapeutic Interferon Interchange in Relapsing Multiple Sclerosis Lowers Health Care and Pharmacy Expenditures with Comparable Safety.

Introduction: For patients with a less-active (fewer relapses or complete recovery from relapses, less radiologic burden of disease, or no or limited disease-related disability) relapsing form of multiple sclerosis (MS), interferon (IFN) beta-1b subcutaneous is similar in efficacy to IFN beta-1a intramuscular and subcutaneous. The purpose of this study was to assess the impact of patient interchange from an IFN beta-1a to IFN beta-1b.

Methods: This was a retrospective, pre-post study of adult patients with relapsing MS who underwent interchange from an IFN beta-1a to IFN beta-1b between April 15, 2014, and April 30, 2015. Health care financial and utilization outcomes between the 6 months before and after interchange were compared, and safety outcomes after interchange were assessed.

Results: A total of 36 primarily white, middle-age, and female patients underwent interchange. Monthly total health care and pharmacy expenditures decreased by approximately 40% and 44%, respectively, from pre-to-post interchange (p < 0.001). Health care utilization was unchanged (p < 0.05). Seven (43.8%) patients underwent interchange back to IFN beta-1a intramuscular. No patients underwent interchange back to IFN beta-1a subcutaneous. The most common adverse effect reported after interchange was injection-site reaction.

Conclusion: Health care expenditures decreased and adverse effects were limited among patients with MS who underwent an interchange from an IFN beta-1a to IFN beta-1b. These findings suggest that a therapeutic interchange between IFNs for patients with less-active MS disease is well tolerated. Further research is needed to determine the impact of such an interchange on disease progression.