Impact of Rituximab on relapse rate and disability in an Ecuadorian cohort of patients with neuromyelitis optica spectrum disorders

Background: Neuromyelitis Optica Spectrum Disorder (NMOSD) is a severe inflammatory demyelinating disease of the central nervous system that often causes disability. Based on evidence from prospective and retrospective studies, Rituximab (RTX) has been used as the first-line of therapy in NMOSD. Nevertheless, evidence of the impact of RTX on relapse rate and disability in Ecuadorian patients with NMOSD is lacking. Objective: To evaluate the impact of RTX in an Ecuadorian cohort of patients with NMOSD. . Materials and methods: A retrospective study was conducted in a cohort of patients with NMOSD who received treatment with RTX in a third-level hospital in Quito, Ecuador. Digital medical records of NMOSD patients were reviewed to attain sociodemographic data, disease characteristics, and treatment with RTX. The annualized relapse rate ARR, as well as the degree of disability measured through the expanded disability scale (EDSS), was established before and after treatment. Results: Twenty-three patients with NMOSD treated with RTX were included, the mean age of onset of the disease was 37.2 years (range, 13-64.5). The average duration of disease was 8.5 years (range, 1.3-34.4). Positivity for antibodies against aquaporin-4 (AQP4-IgG) was identified in 78% of the patients. The mean duration of the treatment with RTX was 40 months (range, 12-61). After the RTX therapy, the number of relapses was reduced in 91% (21/23) of cases. The annualized relapsed rate (ARR) was reduced with RTX from 1.89 to 0.12 (p <0.001). The mean EDSS was also reduced from 4.8 to 3.9 (p = 0.014). In all patients, the mean EDSS was reduced or stabilized with RTX. Overall, the drug was well tolerated, the most frequent adverse events were infections which were present in 65.2% of cases. Conclusions: Though with the limitations of and observational study, our data support RTX effectiveness and safety in an Ecuadorian cohort of patients with NMOSD.