Risk of venous thromboembolism in neuromyelitis optica patients hospitalized for acute relapse

Background: Neuromyelitis optica spectrum disorder (NMOSD) patients may be at increased risk of venous thromboembolism (VTE) not only due to ambulatory disability but also due to systemic autoimmune and inflammatory mechanisms altering the hemostatic balance. Objective: To compare the risk of VTE in NMOSD versus multiple sclerosis (MS) patients hospitalized for acute relapses. Methods: Hospital admissions for MS or NMOSD exacerbations were retrospectively identified. Demographics and medical history were recorded. The relationship between visit diagnosis and presence of VTE within 6 weeks of relapse onset was assessed by univariate logistic regression. A multivariate model evaluated the relationship between diagnosis, age, race, gender, body mass index (BMI), disease modifying therapy use, oral corticosteroid use, oral contraceptive use, smoking, length of stay (LOS), and ambulatory status on VTE risk. Results: A total of 30 NMOSD patients had 55 hospitalizations; 179 MS patients had 264 hospitalizations. Six NMOSD patients and one MS patient had VTE. NMOSD visits compared to MS visits had an odds ratio (OR) of VTE of 32.2 (p = 0.002). NMOSD was more likely to be associated with VTE (OR = 17.4; p = 0.01) controlling for age, LOS, and ambulatory disability. Conclusion: NMOSD may be a risk factor for VTE. Larger prospective studies are required to confirm this risk and determine implications for prophylaxis.