Background <p>Monocyte chemoattractant protein-1 (MCP-1) has been implicated in the pathogenesis of chronic kidney disease (CKD); however, its clinical significance in CKD remains unclear. This study investigated the association between plasma MCP-1 levels and kidney and cardiovascular outcomes in patients with CKD.</p> Methods <p>This multicenter, prospective, observational analysis used data from the BRIGHTEN study. Participants with anemia and CKD (eGFR &lt; 60 mL/min/1.73 m²) were classified into four groups based on quartiles of their baseline plasma MCP-1 levels. The primary outcomes included kidney outcomes (a composite of initiation of maintenance dialysis, kidney transplantation, 50% decline in eGFR, or eGFR ≤ 6 mL/min/1.73 m²), the annual rate of eGFR decline, cardiovascular outcomes, and all-cause mortality. Associations were assessed using Cox proportional hazard and linear mixed-effects models.</p> Results <p>This study included 1,447 participants with advanced CKD (median eGFR 17.9 mL/min/1.73&#xa0;m²). The group with the lowest MCP-1 level (&lt; 324.5 pg/mL) had the highest baseline eGFR. In the univariable analyses, higher MCP-1 levels were associated with an increased risk of kidney and cardiovascular outcomes (log-rank <i>p</i> &lt; 0.01 and <i>p</i> = 0.03, respectively), although these associations were not significant after multivariable adjustment. Analysis of the annual eGFR decline using a multivariable linear mixed-effects model revealed that higher MCP-1 levels were associated with an additional eGFR decline of approximately 1.0 mL/min/1.73 m² per year compared to the lowest MCP-1 group. MCP-1 levels were not associated with mortality.</p> Conclusions <p>In patients with CKD, higher plasma MCP-1 levels are associated with a more rapid decline in kidney function but not with the composite outcome of kidney failure. MCP-1 was not associated with cardiovascular outcomes or mortality in this population cohort.</p>