Abstract
Introduction: Safety concerns leading to treatment discontinuation pose significant challenges in Multiple Sclerosis (MS) management Objectives/Aims: The outcomes of the study were to compare the two groups in terms of total count of relapses, time to first relapse, confirmed-disability-worsening (CDW) at 24&48 weeks, and Progression Independent of Relapse Activity (PIRA). Propensity-score-matching with inverse-probability-weighting (PS-IPTW) was used to balance baseline characteristics between groups. Methods: A multi-center, longitudinal cohort study was conducted using data from the MSBase registry. Patients aged >18 years, diagnosed with relapsing-remitting MS (RRMS) who had been treated with OCR, for a minimum of one year who recorded one safety event during treatment. Patients were categorized into two groups: those who discontinued Ocrelizumab (OCR) due to safety concerns (Switchers) and those who continued treatment despite adverse events (Continuers). Results: From an initial cohort of 10,774 patients, 310 Switchers and 1,315 Continuers were identified. After propensity score matching, 66 pairs were analyzed. The mean time on OCR for Switchers was 2.7 }1.2 years, whilst for the Continuers was 4.4}1.2 years. Infections (43.9%) and cancers (9.1%) were the main safety events leading to discontinuation. Among matched pairs, Switchers had a higher trend in relapse count than Continuers (PS-IPTW RR 2.62, 95%CI 0.96-7.15, p=0.060). Time to first-relapse showed no differences. CDW at 24 weeks trended higher for Switchers (HR 2.08,95%CI 0.96-4.51, p=0.064), with no differences at 48 weeks. PIRA-risk also trended in Switchers (HR2.45, 95%CI 0.95-6.29,p=0.063). Conclusion: Switching from OCR due to safety concerns may increase relapse risk, mitigated by transitioning to high-efficacy DMTs.