The Neutrophil-to-Lymphocyte Ratio and the Monocyte-to-Lymphocyte Ratio Predict Expanded Disability Status Scale Score at One Year in Pediatric Neuromyelitis Optica Spectrum Disorder but not in Multiple Sclerosis

Background: The neutrophil-to-lymphocyte ratio (NLR) and monocyte-to-lymphocyte ratio (MLR) are inflammatory biomarkers that may predict disease course in neuroinflammatory diseases. We examine whether NLR or MLR at the time of the first attack predicts longitudinal disease outcomes in pediatric neuromyelitis optica spectrum disorder (NMOSD) and multiple sclerosis (MS).Methods: Clinical data were collected retrospectively at a single institution. NLR (ratio of percent neutrophils to percent lymphocytes) and MLR (ratio of percent monocytes to percent lymphocytes) were calculated in the complete blood cell count at the time of presentation before treatments. Expanded Disability Status Scale (EDSS) score and time to next relapse were used as the outcome assessments. Results: Twenty-eight patients with MS and eight patients with aquaporin-4-positive NMOSD were included. For NMOSD, NLR at presentation associated with EDSS at six months (P = 0.003) and one year (P = 0.032) even when adjusting for age at presentation. MLR associated with EDSS at six months (P = 0.0203) and EDSS at one year (P = 0.0079). However, NLR and MLR did not predict EDSS scores in MS. MLR and NLR did not predict time to next relapse or did not associate with magnetic resonance imaging activity in MS and NMOSD. Changes in MLR and NLR were observed with disease-modifying therapies but did not predict disease activity. Conclusions: NLR and MLR associated with six-month and one-year EDSS in children with NMOSD but not in MS. Future studies should explore whether changes in NLR and MLR could predict disease activity or treatment efficacy.