Mortality of neuromyelitis optica spectrum disorders in a Chinese population

OBJECTIVE Neuromyelitis optica spectrum disorder (NMOSD) is a rapidly disabling disease. Epidemiologic studies have suggested varying NMOSD mortality across ethnic groups. However, NMOSD mortality data in China are scarce. This study's objectives were to explore mortality and causes of death among Chinese NMOSD patients and to identify independent predictors of death. METHODS We performed a retrospective study with a 10-year follow-up of Chinese NMOSD patients. A Cox proportional hazards model was used to identify independent predictors of death. RESULTS Five hundred and sixty-nine patients were included; 24 patients died during follow-up, for overall mortality of 4.2%. In these patients, the median disease duration at the time of death was 3.4 years. The most common cause of death was secondary infection (62.5%), especially respiratory infection (45.8%). The second most common cause of death was extensive cervical myelitis with respiratory failure (16.7%). Other causes included suicide (8.3%), cancer (4.2%), cerebral embolism (4.2%), and unknown causes (4.2%). The multivariate Cox analyses indicated that a short first interattack interval (HR = 0.93, 95% CI 0.89-0.98, p = 0.003), lack of regular immunotherapy (HR = 10.34, 95% CI 4.05-26.37, p < 0.001), and older age at onset were independent predictors of death. Every increasing decade of onset age increased the risk of death 2.59 times (95% CI 1.74-3.86, p < 0.001). INTERPRETATION Infections were more common in patients not treated with any immunotherapy, indicating that early and consequent immunotherapy might prevent death by infections, which is of great importance for further treatment of NMOSD patients to avoid undertreatment due to fear of treatment-associated infections.