Treatment satisfaction during personalized extended interval dosing of natalizumab in patients with multiple sclerosis

BACKGROUND: Extended interval dosing (EID) of natalizumab is increasingly used in clinical practice for patients with multiple sclerosis, driven by growing evidence supporting its sustained efficacy and associated benefits. However, it remains unclear whether EID, particularly at dosing intervals beyond six weeks, affects treatment satisfaction. OBJECTIVES: To investigate whether natalizumab dosing intervals of up to ten weeks are associated with patient-reported treatment satisfaction. METHODS: Participants from the prospective NEXT-MS and SUPERNEXT trials, both evaluating concentration-guided EID while preserving therapeutic drug concentrations, completed longitudinal Treatment Satisfaction Questionnaire for Medication (TSQM) assessments. Associations between dosing interval and scores in the four TSQM domains (Effectiveness, Side effects, Convenience, and Overall satisfaction) were analyzed using linear mixed-effects models. RESULTS: A total of 427 participants were included. Most participants reported high treatment satisfaction. No overall association was observed between dosing interval and TSQM scores. However, additional effect-modification analyses suggested that the association between dosing interval and treatment satisfaction differed according to treatment duration, disease duration, baseline EDSS, and route of natalizumab administration. CONCLUSIONS: Treatment satisfaction was high and was not affected by longer dosing intervals in the majority of patients. However, additional effect-modification analyses indicated that the impact of dosing interval on treatment satisfaction may differ according to patient characteristics, highlighting the importance of individualized treatment decisions.