Low body mass index can be associated with the risk and poor outcomes of neuromyelitis optica with aquaporin-4 immunoglobulin G in women

Neuromyelitis optica spectrum disorder with aquaporin-4 immunoglobulin G (NMOSD-AQP4) is an inflammatory disease of the central nervous system (CNS). Recent studies have demonstrated that body mass index (BMI) can be associated with the risk and/or outcomes of diverse inflammatory diseases, such as rheumatoid arthritis (RA), psoriasis, Hashimoto’s thyroiditis and multiple sclerosis (MS). However, the clinical implication of BMI in NMOSD-AQP4 is still unknown. ### Patients A total of 157 patients with NMOSD-AQP4 who had their first episodes between 1982 and 2016, from six nationwide tertiary referral hospitals, were finally included (see figure 1 in the online Supplementary file 1). Patients were tested for antiaquaporin-4 (AQP4) antibody using either the fluorescence-activated cell sorting assay or cell-based assay.1 In the NMOSD-AQP4 group, BMI measured within 1 month of the first symptom of NMOSD-AQP4 and before any steroid treatment, immune suppressant, or immune modifying treatment (BMInaive) and the lowest BMI measured within 1 year of the first symptoms of NMOSD-AQP4 (BMImin-1yr) were obtained, respectively. BMI values less than 18.5 kg/m2 were classified as low according to the WHO recommendation. Demographic information, number and location of attacks, results of the cerebrospinal fluid examination and maximal score of the Kurtzke Expanded Disability Status Scale (EDSS) on disease onset were assessed. Prognosis was evaluated in terms of the time to a confirmed EDSS of 6 (EDSS6), functional system score of 4 for visual function (VF4) and mortality. ### Supplementary file 1 [jnnp-2017-317202-SP1.jpg] ### Healthy controls and MS controls A matched case–control study was performed to evaluate the association between BMI and risk for NMOSD-AQP4. The controls were selected from the 96 146 participants included in the nationwide population-based survey of the health and nutritional status of Korea (Korean National Health and Nutrition Examination Survey (KNHANES))2 conducted in 1998, 2001, 2005 and 2007–2015. Four controls were matched to each case based on age, sex and year of BMI measurement (within …