Real-world use of disease-modifying therapy in persons with multiple sclerosis aged 55 and over.

Background: As the average age of multiple sclerosis (MS) population rises globally, unclear guidelines on disease-modifying therapy (DMT) use in older persons with MS (pwMS) contribute to increased variability in clinical practice. The factors driving DMT utilisation in this population are not well understood. We explored DMT utilisation patterns in pwMS aged 55 and older enrolled in the Swiss MS Registry (SMSR), a nationwide observational study with voluntary participation. Methods: We conducted an exploratory analysis using data from SMSR participants who had reported DMT status in the most recent follow-up survey and at least once within the previous 3 years. Participants were categorised and compared by current and past DMT use: Results: Among 378 participants (mean age 63.2±6.7 years), 206 (54.5%) reported DMT use: 176 (46.6%) continued the same DMT, 20 (5.3%) switched and 10 (2.6%) newly initiated DMT. Among non-users, 54 (14.3%) had stopped treatment, while the rest did not use DMT during the study period. In participants with regular neurological care, longer MS duration (relative risk (RR)=1.018, 95% CI 1.008 to 1.028) and older age (RR=1.016, 95% CI: 1.001 to 1.032) were associated with higher likelihood of DMT non-use, and participants with primary (RR=1.736, 95% CI: 1.175 to 2.565) and secondary progressive MS (RR=1.423, 95% CI: 1.023 to 1.981) were more likely not to use DMTs compared with relapsing-remitting MS. No significant associations were observed in participants without regular neurological follow-up. Conclusions: Despite unclear efficacy and safety, many older pwMS continue DMT use. Use is primarily associated with relapsing-remitting MS, while age and disease duration show only modest or no association.