Monocyte-to-Lymphocyte Ratio as a Marker of Cardiovascular Risk in Individuals with Chronic Kidney Disease: A Systematic Review of Observational Studies

AimTo evaluate the association between monocyte-to-lymphocyte ratio (MLR) and cardiovascular outcomes in chronic kidney disease (CKD). MethodsWe systematically searched Medline, EMBASE, Web of Science, and Scopus from inception to May 28, 2025. We included peer-reviewed observational studies assessing MLR and cardiovascular outcomes or all-cause death in CKD. Two reviewers independently screened studies, extracted data, and assessed risk of bias using the Newcastle-Ottawa Scale. Findings were narratively synthesized and p-values pooled using Fishers method. Statistical significance was set at p < 0.05. ResultsEleven studies (n = 18,631) met our inclusion criteria. The study population ranged from non-dialysis CKD to end-stage kidney disease on dialysis, with follow-up from 1 to 24 months. Five studies (n = 16,974) examined cardiovascular death and generally reported significant associations with elevated MLR; Fishers method indicated strong overall evidence (p < 0.001). Six studies (n = 4,587) assessed cardiovascular events, yielding inconsistent findings, although some reported significant associations and identified predictive thresholds (e.g., 0.43). Five studies (n = 15,682) showed increased risk of all-cause death with increasing MLR and a predictive threshold of 0.63. Fishers method again supported strong overall evidence (p < 0.001). All except one of the eleven studies were rated as good quality. ConclusionElevated MLR could predict cardiovascular and all-cause death in CKD. Evidence for cardiovascular events remains inconsistent, and thresholds proposed in individual studies may not be generalizable. Large-scale, multi-ethnic, and prospective studies with standardized protocols are needed to validate MLRs role in cardiovascular risk stratification.