Serum Sclerostin and Adverse Outcomes in Nondialyzed Chronic Kidney Disease Patients

Background: The chronic kidney disease (CKD)-mineral and bone disorder (MBD) syndrome is an important contributor to the CKD-associated cardiovascular disease and high mortality rates. Sclerostin, a protein synthesized in osteocytes, is a potent downregulator of bone metabolism and a novel candidate for the bone-vascular axis in CKD patients. We tested whether serum sclerostin values are predictive for all-cause mortality and cardiovascular events (CVEs) in a CKD population. Methods: Serum sclerostin was obtained from 173 CKD (stage 3-5) and 47 control patients, and its concentration was correlated with estimated glomerular filtration rate and to mineral and vascular abnormalities that are present in the CKD evolution. All-cause mortality and CVEs were also analyzed in relation to serum sclerostin values. Results: Patients with CKD showed higher sclerostin levels (median 63.5 pmol/L vs 52 pmol/L, P .001) than controls, with values progressively higher across the CKD stages. In univariate analysis, serum sclerostin concentrations were correlated with gender, estimated glomerular filtration rate, flow-mediated dilatation, and endothelium-independent vasodilatation as markers of endothelial dysfunction and with different serum CKD-MBD-associated parameters. However, in multivariate analysis, only gender, fibroblast growth factor-23, phosphate, flow-mediated dilatation, and cholesterol remained significantly associated with sclerostin levels. During the observational period, there were 19 deaths and 50 CVEs. In survival analysis, different sclerostin levels were associated with all-cause mortality and CVEs in these patients. Conclusions: This is the first study that shows that serum sclerostin values are associated, even after multiple adjustments, with fatal and nonfatal CVEs in a nondialyzed CKD population.