The neutrophil-to-lymphocyte ratio as disease actvity marker in multiple sclerosis and optic neuritis

Background: Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS). The neutrophil-to-lymphocyte ratio (NLR) has been identified as a disease activity marker in several diseases. We aim to evaluate the significance of the NLR in the different subtypes of MS, optic neuritis (ON) and in relation to disease activity and Expanded Disability Status Scale (EDSS). Methods: We included 378 patients and 813 healthy controls (HC) from The Nordic Reference Interval Project 2000 (NORIP). Complete blood count, demographic and clinical data from patients were evaluated retrospectively. The NLRs were compared for all participants by Student's t-test. The comparison of NLR between relapse and remission, SPMS and PPMS, and RRMS and progressive MS were all adjusted for age, gender, EDSS and disease duration by using the linear regression model. Pearson correlation analysis was made between NLR and time of blood sampling. Logistic regression models were constructed for EDSS = 4.0 as outcome. Results: The NLR was significantly higher (p< 0.001) in MS and ON compared to HC. Patients in relapse had a higher NLR (p< 0.01) than patients in remission. No difference in NLR was found between RRMS and progressive MS patients and neither between SPMS and PPMS patients. No association was found between NLR and an EDSS score = 4.0. Conclusion: NLR was higher in MS and ON patients compared to HC, indicating the occurrence of chronic inflammation. NLR may be an inexpensive and easily accessible supplemental marker of disease activity in RRMS. This needs confirmation in future trials.