Treatment persistence in paediatric-onset multiple sclerosis: A Swedish nationwide registry study

BACKGROUND: Comparative studies in paediatric-onset multiple sclerosis (PoMS) that also include highly effective monoclonal antibody therapies are rare. OBJECTIVE: To compare treatment persistence, as a proxy of effectiveness and tolerability, across disease-modifying therapies (DMTs). METHODS: Nationwide cohort study using Swedish MS Registry data on individuals with MS onset before age 18 from 2000 to 2024. Treatment persistence was analysed using Kaplan-Meier and Cox models, adjusted for demographics and treatment epoch. RESULTS: We included 383 individuals (69.2% female; median onset age 15.8 and 17.2 years at first DMT start), observed for a median 10.1 years (interquartile range (IQR): 5.5-15.5), yielding 934 treatment episodes: rituximab (272), injectables (263), natalizumab (248), fingolimod (86) and dimethyl fumarate (65). Median age at any treatment initiation, regardless of treatment sequence, was 18.9 years, with a median Expanded Disability Status Scale (EDSS) score of 1.5 (IQR: 0.0-2.0). Treatment persistence never dropped below 50% for rituximab, while median persistence was 35.6 months for natalizumab (95% confidence interval (CI): 28.8-44.9), 34.7 for dimethyl fumarate (95% CI: 21.7-56.9), 32.0 for fingolimod (95% CI: 21.1-48.1) and 17.6 for injectables (95% CI: 14.4-20.8). Compared to injectables, adjusted hazard ratios (HRs) for discontinuation were significantly lower for rituximab (0.09; 95% CI: 0.07-0.12), natalizumab (0.39; 95% CI: 0.31-0.48), fingolimod (0.41; 95% CI: 0.30-0.55) and dimethyl fumarate (0.49; 95% CI: 0.36-0.68). CONCLUSION: Rituximab displayed the highest treatment persistence, supporting B-cell depletion as a first-line option in PoMS.