Dynamics of neutrophil-to-lymphocyte ratio and disability status during an acute relapse and corticosteroid therapy in relapsing-remitting multiple sclerosis

Objectives The neutrophil-to-lymphocyte ratio (NLR) is an easily obtainable blood-based marker reflecting systemic inflammation and immune activation. Its temporal behavior during relapses, corticosteroid treatment, and recovery in relapsing-remitting multiple sclerosis (RRMS) remains unclear. The objective of this study was to evaluate longitudinal changes in NLR and disability measured by Expanded Disability Status Scale (EDSS) across relapses, end of corticosteroid therapy, and one-month follow-up in RRMS. Methods A total of 20 patients with RRMS relapses and 60 healthy controls were included in our study. Blood samples were collected once from controls and three times from patients: before corticosteroid therapy (BT), at the end of treatment (ET), and one month after therapy (1 M). NLR was calculated from automated complete blood counts. EDSS was scored by a trained neurologist at each visit. Statistical analyses were performed using SPSS. Correlation between NLR and EDSS was evaluated using repeated-measures correlation (rmcorr) in RStudio. Results NLR was significantly higher in BT vs. controls (p=0.009) and increased further at ET (p<0.001), followed by a decline at 1 M (p=0.034). EDSS scores decreased significantly at ET and remained lower at 1 M. Receiver Operating Characteristic (ROC) analysis showed moderate discrimination for BT vs. control groups (AUC=0.696, p=0.009) and ET vs. BT (AUC=0.727, p=0.014), while 1 M vs. ET was not significant (AUC=0.626, p=0.172). Conclusions NLR dynamically reflects both inflammatory activity and corticosteroid-induced immune modulation in RRMS. Although its diagnostic power is modest, NLR is a practical, cost-effective biomarker that may complement clinical and radiological tools in monitoring relapse and treatment response.