Intraindividual Interleukin-6 Variations on the Cardiovascular Prognosis of Patients with Chronic Renal Disease

In chronic kidney disease (CKD) patients on dialysis, plasma interleukin (IL)-6 levels predict mortality better than other markers. Impact of intraindividual changes of inflammatory markers on cardiovascular (CV) events in CKD patients is unknown. The aim of this study is to demonstrate the relation between CV outcomes and variations of C-reactive protein (CRP), IL-6, IL-1β, and tumor necrosis factor (TNF)-α in CKD. Ninety patients (mean age: 68.5 ± 12.8 years) at different stages (1-4) of CKD were evaluated. Serum CRP, IL-6, IL-1β, and TNF-α were measured basally and after taking statins or angiotensin II receptor blockers. Three patterns were defined for each marker (baseline, mean of two measurements, and variation of the marker: increase or decrease after 6 months). During follow-up (mean time: 72.7 ± 19.8 months), 14 patients died, 11 were included on dialysis program, and 29 suffered a CV event. Patients with persistently elevated IL-6 values had higher risk to develop CV events [OR = 1.21 (1.11-1.32), p = 0.001]. Mean of two measurements of IL-6 was a better predictor for events than a single measurement of IL-6, CRP, TNF-α, and IL-1β. A mean of two determinations of plasma IL-6 greater than 6 pg/mL and previous peripheral vascular disease was related to an increased risk for CV events [2.34 (1.05-5.22), p = 0.037 and 2.95 (1.27-6.93), p = 0.011, respectively] in an adjusted Cox regression model. IL-6 is a better inflammatory marker than CRP, TNF-α, and IL1β at predicting CV events in CKD nondialysis patients. Mean of two measurements is better than simple determinations at predicting CV outcome.