664 relapses were assessed. Predictors of mRS 3-5 on admission were age at relapse over 60 (OR 13.31, 95% CI 1.89-93.76) and number of prior relapses (OR 1.29, 95% CI 1.04-1.60) but not being on a DMT during relapse. 37% of relapses requiring admission were associated with adverse events, and 22% had an infectious complication. Rituximab showed a relapse-free survival probability of 63.1% at 10 years, while no relapses were observed on eculizumab, inebilizumab, or satralizumab. Rituximab had an ARR of 0.135 (95% CI 0.09-0.188), compared to 0.00004 (0.000-0.023) for eculizumab, 0.00007 (0.000-0.037) for inebilizumab, 0.00007 (0.00-0.048) for satralizumab, 0.26 (0.133-0.420) for MMF, and 0.83 (0.262-1.82) for azathioprine. 315 non-relapse hospitalizations were analyzed. Infections were the most common cause of admission (53%), shock and respiratory failure were common complications and mortality rate was 5%.  The composite endpoint of relapse or serious infectious adverse events (AEs) showed better survival probabilities for eculizumab (83% at 5 years), inebilizumab (75% at 3 years), and satralizumab (90% at 5 years) than rituximab (52% at 5 years), MMF (32% at 5 years), and azathioprine (8% at 5 years).