Neuromyelitis Optica Spectrum disorder - Clinical profile, treatment and risk factors for relapse in three tertiary hospitals in South Africa. An observational study.

INTRODUCTION: Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune inflammatory syndrome characterised by Aquaporin-4 antibodies (AQP4 Ab). Clinical presentations include optic neuritis, longitudinally extensive transverse myelitis (LETM), area postrema syndrome, diencephalic and cerebral syndromes. Immunosuppressants are used to prevent relapses and disability. There is little data from sub-Saharan Africa on the clinical presentations and outcomes of patients with NMOSD.

METHODS: An observational study was conducted between January 2023 and June 2024 at three hospitals in Johannesburg, South Africa. We included all patients with NMOSD who had a minimum of 12 months follow up after diagnosis. Data was collected on demographics, clinical manifestations, AQP4 Ab status, immunosuppressive medications used, and relapses.

RESULTS: Thirty-nine patients were recruited, all black African; 36 (92.3 %) were female, and 35/39 (89 %) were AQP4 Ab positive. Twelve patients were living with HIV. The most common clinical presentation was optic neuritis (38 %), followed by LETM (31 %). One or more relapses occurred in 24 patients (62 %). No significant risk factors for relapse were identified. Rituximab had the lowest relapse rate at 0.10 relapses per patient-year compared to azathioprine (0.23 relapses per patient-year) and mycophenolate mofetil (0.54 relapses per patient-year). No significant side effects were noted in people living with HIV and HIV negative patients using rituximab.

CONCLUSION: Chronic immunosuppression with rituximab was associated with the lowest relapse rate. In our population with a heavy burden of HIV, we have had no serious adverse events with using rituximab, which should be recommended as a first-line immunosuppressive agent in our setting.