Comparison of Efficacy and Safety in Patients Switching From MabThera® to Rixathon® in Relapsing-Remitting Multiple Sclerosis

This observational study investigates if switching from MabThera® to Rixathon® is associated with changes in disease activity and/or safety in people with multiple sclerosis (MS). The main questions it aims to answer are: * Does switching to Rixathon® affect tissue damage, measured by blood levels of neurofilament light (pNfL)? * Does switching to Rixathon® affect the number of new MRI lesions, relapses, or disability progression? Researchers will look at health information already collected from participants before and after the medication switch. Participants include people with MS treated at Uppsala University Hospital who switched from MabThera® to Rixathon® starting in January 2023. Researchers will use data from regular clinical visits, blood tests, brain MRI scans, and disability scores (EDSS) recorded in the Swedish MS Registry.