Neutrophil-to-Lymphocyte Ratio (NLR)-Independent Prognostic Marker of Renal Function Decline in Chronic Kidney Disease: A Systematic Review and Meta-Analysis.

Background/Objectives: Chronic kidney disease (CKD) progression is strongly influenced by systemic inflammation. The neutrophil-to-lymphocyte ratio (NLR), derived from routine blood counts, reflects the balance between innate and adaptive immunity and has been proposed as a marker of adverse renal outcomes. We hypothesized that elevated baseline NLR is associated with reduced kidney function and increased risk of progression to end-stage kidney disease (ESKD) in adults with non-dialysis CKD. Methods: Following PRISMA guidelines, we systematically searched MEDLINE, Embase, and Scopus for studies enrolling adults with CKD stages 1-4 that reported renal outcomes according to baseline NLR. The primary outcome was progression to ESKD or renal replacement therapy (RRT) initiation. Results: Six eligible studies were identified, of which four provided sufficient data for meta-analysis. Across cohorts, elevated baseline NLR was consistently associated with adverse renal outcomes. In pooled analyses, high NLR nearly doubled the risk of ESKD or RRT (RR 1.96, 95% CI 1.30-2.97). Leave-one-out sensitivity analysis strengthened the association while reducing heterogeneity. For kidney function, higher NLR was associated with lower baseline eGFR (SMD -1.59, 95% CI -2.38 to -0.80). Conclusions: Elevated NLR is a robust prognostic marker of renal function decline and progression to ESKD or RRT in non-dialysis CKD. As a simple and inexpensive biomarker, NLR offers additional predictive value beyond eGFR and albuminuria. Incorporating NLR into risk models may refine stratification, guide follow-up, and enable earlier therapeutic optimization. Prospective large studies are warranted to establish thresholds and validate its role in clinical practice.