Platelet-to-lymphocyte ratio differs between MS and NMOSD at disease onset and predict disability.

Background: We aimed to assess platelet-to-lymphocyte (PLR) and neutrophil-to-lymphocyte ratios (NLR) for differentiating multiple sclerosis (MS) from aquaporin-4-antibody-positive neuromyelitis optica spectrum disorders (NMOSD) at disease onset.
Methods: We retrospectively enrolled and reviewed the medical records of patients with MS (N = 50) and NMOSD (N = 33) followed in specialized MS/NMOSD centers from Argentina. Demographical and clinical (manifestation and disability) data and neuroradiological features (new/enlarging or contrast-enhancing lesions) were assessed at baseline, 1 and 2 years. Serum samples were obtained during the first relapse without a previous acute or chronic treatment, at 1 and 2 years. Mixed-effects model was used to identify independent associations between the log-transformed NLR or PLR and MS/NMOSD outcomes.
Results: PLR is increased in NMOSD when compared to MS (229.4 ± 86.74 vs. 186.6 ± 70.17, P = 0.01), but no significant differences were found for NLR (3.51 ± 1.29 vs. 3.30 ± 1.17, P = 0.43). PLR was the only independent predictor of poor physical disability score (EDSS ≥ 4) in NMOSD patients at 2 years (β=0.28, p = 0.02) after applying multivariate mixed-effects regression analysis. Additionally, multivariate logistic regression analysis showed that the PLR was the only independent predictor of EDSS ≥ 4 at 2 years (OR 28.8, p = 0.041) in the NMOSD group. The area under the receiver-operating characteristic curve was 0.841.
Conclusion: PLR could be potentially useful as additional diagnostic tool in differentiating these two neuroinflammatory conditions at presentation. PLR can predict severity of neurological disability at 2 years in NMOSD patients.
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