The description of neuromyelitis optica spectrum disorder: Patient registry in Yangtze River Delta area of China

To describe the clinical features of neuromyelitis optica spectrum disorder (NMOSD) through patient registry in Yangtze River Delta area of China. A total of 502 consecutive patients diagnosed with aquaporin-4 antibody (AQP4-ab)-positive NMOSD were registered between December 2018 to January 2021 in multiple tertiary referral centers within the framework of Yangtze River Delta of China. Their baseline data were reviewed, and follow-up clinical information were collected prospectively. The mean age at onset was 37.3 (range 3–80 years) years and the female-to-male ratio was 8.1:1. The median disease duration was 47 months (interquartile range [IQR] 25–84 months). A total of 1372 attacks of the 502 patients were recorded till the last follow-up, with a median annualized relapse rate of 0.4 (IQR 0.3–0.6). Nearly one-fourth (24.5%, 336/1372) of the attacks had prodromic events, including upper respiratory tract infection (36.3%, 122/336), fever (20.2%, 68/336) and pregnancy-related issues (17.9%, 60/336), etc. Myelitis was the most common attack type throughout the disease course (51.4%, 705/1372), followed by optic neuritis (ON, 43.1%, 592/1372). As for onset phenotype, ON (37.3%, 187/502) prevailed over myelitis (28.3%, 142/502). The median time to first relapse was 12 months (IQR 5–25 months). Patients with brainstem encephalitis at onset were more likely to have other anatomical region involved in subsequent attacks (p