Comparisons of the efficacy and tolerability of mycophenolate mofetil and azathioprine as treatments for neuromyelitis optica and neuromyelitis optica spectrum disorder

Background and purpose: To research and compare the efficacy and tolerability of mycophenolate mofetil (MMF) and azathioprine (AZA) in neuromyelitis optica (NMO) and NMO spectrum disorder (NMOSD). Methods: In this observational study, we enrolled patients with NMO/NMOSD who received either MMF or AZA for 6 months or more. We compared the efficacy and tolerability of MMF and AZA as preventive treatments in patients with NMO/ NMOSD. Results: Baseline variables between groups were not significantly different. In the MMF-treated (n = 105) and AZA-treated (n = 105) groups, 56.2% and 52.4%, respectively, of patients were relapse-free, and both median annualized relapse rates and Expanded Disability Status Scale scores were lower (P = 0.000). More patients in the AZA than MMF group stopped or switched to another preventive treatment because of adverse effects. The Expanded Disability Status Scale scores at final follow-up were lower in the AZA group than in the MMF group, the duration after treatment was longer in the AZA group than in the MMF group, and more patients in the AZA than MMF group concurrently used prednisone (P < 0.05). Neither the Kaplan-Meier survival estimates (P > 0.05) nor the Cox proportional hazard model (P > 0.05) indicated a significant difference in relapse between MMF-and AZA-treated groups. Conclusions: Both MMF and AZA were effective in patients with NMO/ NMOSD. Fewer and more mild adverse events were attributed to MMF than AZA. The probability of maintaining a relapse-free state was not significantly different between the MMF and AZA groups. However, more effective treatments with more acceptable safety profiles are still needed.