Comparative Evaluation of Neutrophil-to-Lymphocyte ratio and Platelet-to-Lymphocyte ratio with Erythrocyte Sedimentation Rate and C-Reactive Protein as Markers of Systemic Inflammation.

Background: Neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) are used as hematological markers of systemic inflammation. However, their performance compared with conventional biomarkers i.e., erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) requires further investigation. This study assesses the association and diagnostic performance of NLR and PLR against ESR and CRP-defined systemic inflammation. Methods: In this cross-sectional analytical study, 4,553 eligible individuals were enrolled and their laboratory data was noted. Correlation of NLR and PLR with ESR and CRP was tested by applying Spearman’s rank correlation. After categorizing participants into normal and inflammatory group on basis of their ESR and/or CRP status, differences in their NLR and PLR values were assessed using the independent t-test. The diagnostic ability of NLR and PLR to discriminate ESR and/or CRP defined inflammation was analyzed using receiver operating characteristic (ROC) curve. Multivariable logistic regression was applied to test their independent association with systemic inflammation, after adjustment for confounding factors such as age, gender and hemoglobin. Results: NLR and PLR were significantly correlated with ESR and CRP (p<0.001) Participants in the inflammatory group had higher NLR and PLR as compared to those in the normal group. ROC demonstrated the limited discriminatory ability of NLR (AUC=0.574, 95% CI: 0.557–0.591) and PLR (AUC=0.552, 95% CI: 0.535–0.569). Multivariable binary logistic regression showed NLR as independent predictor of systemic inflammation (OR: 1.230, p<0.001) while PLR did not show predictive utility (OR: 1.001, p=0.228). Conclusion: NLR demonstrated a stronger and independent association with systemic inflammation compared to PLR. However, given their limited diagnostic accuracy, NLR should be used as a supportive marker in screening for inflammation. Neither NLR nor PLR can fully replace ESR and CRP