Comparative Effectiveness and Risk of Severe Infection in Adult Patients With MS Treated With Diroximel Fumarate Versus Anti-CD20 Monoclonal Antibodies: A Real-World Claims Analysis

INTRODUCTION: Multiple sclerosis (MS) is a chronic, immune-mediated neurological disease, leading to significant morbidity. Over 25 disease-modifying therapies (DMTs) are approved for MS; however, older patients may benefit less from high-efficacy DMTs. We compared the risk of severe infections (SIs) and annualized relapse rate (ARR) by age (< 45 and ≥ 45 years) between diroximel fumarate (DRF) and anti-CD20 monoclonal antibodies (mAbs) in patients with MS. METHODS: This retrospective study utilized the Komodo Health Claims database to identify patients treated with DRF or anti-CD20 agents. Patients were propensity score matched 1:1 on baseline characteristics and stratified by age (younger: < 45 years; older: ≥ 45 years). Infection-related encounters were identified by diagnosis codes; SIs required hospitalization or intravenous antibiotics. MS relapses were based on inpatient or outpatient claims and associated treatments. RESULTS: Between 2016 and 2025, 2894 propensity score-matched patients with MS who initiated DRF (n = 1447) or anti-CD20s (n = 1447) were included. DRF-treated patients had a lower proportion of SIs at 12 and 24 months compared with anti-CD20-treated patients (p ≤ 0.002 at 24 months). Younger DRF-treated patients had significantly fewer SIs (p = 0.005), while older DRF-treated patients had lower non-SI rates. COVID-19-related SIs were also significantly lower in DRF-treated patients (p < 0.001). ARRs were similar between the two groups. CONCLUSION: DRF-treated patients with MS had a significantly lower risk of SI compared with anti-CD20-treated patients, with no difference in ARR. More real-world studies are needed to understand the efficacy and safety of DMTs in the setting of de-escalation in aging patients with MS.