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

Objective: To describe the clinical features of neuromyelitis optica spectrum disorder (NMOSD) through patient registry in Yangtze River Delta area of China.

Methods: 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.

Results: 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 < 0.001), compared to other onset type. The median serum AQP4-ab titer measured by cell-based assays was 1:100 (IQR 1:32-1:320, range 1:10-1:10,000). The baseline AQP4-ab titer in cerebrospinal fluid (r = 0.542, p <0.001), overall ARR (r = 0.232, p< 0.001) and the EDSS scores at last follow-up (r = 0.119, p = 0.022) significantly correlated with baseline serum AQP4-ab titer. Antinuclear antibodies (48.4%), thyroid peroxidase antibodies (30.7%), and anti-SSA antibodies (26.2%) represented the most frequent concomitant antibodies, while autoimmune thyroid disorders (13.1%, 66/502) and Sjogren's syndrome (10.8%, 54/502) were the most common accompanying autoimmune diseases. Till the last follow-up, 403 patients received preventive treatments. Azathioprine represented the most common initial treatment, mycophenolate mofetil and rituximab was the most common second and third-line treatment, respectively. The EDSS score at the last follow-up ranged from 0 to 8.5 with a median of 2 (IQR 1-3).

Conclusions: A comprehensive clinical picture of patients with AQP4-ab-positive NMOSD in Yangtze River Delta area of China was presented. More information on disease tragedy and predictive prognostic factors could be generated through long-term observations.