Association between serum interleukin 8 levels and cardiovascular events in patients with chronic kidney disease.

Introduction: Chronic kidney disease (CKD) is associated with systemic inflammation and elevated pro-inflammatory cytokines. While interleukin (IL)-8 has shown harmful cardiovascular effects in preclinical studies, its role in CKD remains underexplored. The study aimed to (i) determine serum IL-8 concentrations across CKD stages, (ii) identify factors associated with IL-8 concentrations, and (iii) evaluate its association with major adverse cardiovascular events (MACEs) and all-cause mortality. Methods: The Chronic Kidney Disease-Renal Epidemiology and Information Network (CKD-REIN) prospective cohort includes CKD patients with an estimated glomerular filtration rate (eGFR) below 60 mL/min/1.73 m² not on kidney replacement therapy. Baseline serum IL-8 concentrations were centrally measured. MACE was defined as any cardiovascular death, myocardial infarction, stroke and hospital admission for heart failure. Multivariable linear regression was used to identify factors associated with IL-8 concentrations. Adjusted cause-specific Cox proportional hazard models were used to estimate hazard ratios [hazard ratio (HR) (95% confidence interval)] for the first MACE and for mortality. Results: Among 2389 included patients (66% men; median age 68 years; mean eGFR 34.8 mL/min/1.73 m²), median serum IL-8 concentration was 12.2 pg/mL. Higher IL-8 levels correlated with more advanced CKD (P < .001), and were independently associated with lower eGFR, diabetes, prior cardiovascular disease, anemia, elevated C-reactive protein, more medications and lower serum albumin. Elevated baseline IL-8 was associated with a greater adjusted hazard of MACEs in women [HR for 1-unit change in log(IL-8): 1.75 (1.26; 2.43)] but not in men [HR 1.16 (0.93; 1.45)]. The adjusted HR for all-cause mortality was 1.70 (1.40; 2.06), with no difference between men and women. Conclusion: In a large cohort of patients with moderate-to-advanced CKD, higher IL-8 levels were associated with a greater risk of MACEs in women (but not in men) and higher mortality in both sexes. Further research is needed to assess the potential of IL-8 as a cardiovascular risk biomarker, clarify the clinical significance of the sex difference observed here and determine whether targeting IL-8 could reduce cardiovascular risk in CKD.