Risk factors associated with permanent disability in neuromyelitis optica spectrum disorders

Background: Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune inflammatory disease of the central nervous system. In NMOSD, a relapse results in increased disability. Objective: To assess risk factors associated with permanent disability (PD) in patients with neuromyelitis optica spectrum disorders (NMOSD). Methods: We evaluated 34 cases (who developed permanent disability) and 33 controls. The assessment included the following variables: sociodemographic data and characteristics of the disease. Logistic regression analysis was performed to adjust variables associated with PD. Results: fifty-one percent developed PD during follow-up; 15 (22%) developed permanent visual disability, 13 (19%) developed permanent motor disability and 6 (9%) were restricted to wheelchair. Factors associated with PD in the crude analysis were: age at onset >= 50 years (OR 3.95, 95% IC 1.12-13.94, p= 0.032), time from onset to diagnosis >= 12 months (OR 3.30, 95% IC 1.13-9.64, p= 0.029), time from onset to treatment >= 60 months (OR 4.16, 95% IC 1.03-16.85, p= 0.045), EDSS >= 4.0 at the first appointment (OR 3.21, 95% IC 1.18-8.76, p= 0.022) and severe relapses during disease evolution (OR 5.72, 95% IC 1.98-16.57, p= 0.001). Factors associated with PD in the adjusted analysis were: age at onset >= 50 years (OR 5.82, 95% IC 1.30-26.05, p= 0.021), time from onset to diagnosis >= 12 months (OR 5.43, 95% IC 1.47-20.08, p= 0.011) and severe relapses during disease evolution (OR 6.65, 95% IC 1.98-22.31, p= 0.002). Conclusion: Half of patients with NMOSD may develop PD during disease evolution. Age of onset >= 50 years, delay to diagnosis >= 12 months and initial EDSS >= 4.0 constitute the strongest risk factors for PD.