The Ratio of Osteoprotegerin to Fetuin-A Is Independently Associated with Vascular Stiffness in Hemodialysis Patients

Background: The aim of the present study was to compare levels of fetuin-A, osteoprotegerin (OPG), and heat shock protein (HSP)70 according to the stage of chronic kidney disease (CKD), as well as to evaluate the association between serum fetuin-A, OPG, and HSP70 concentrations with respect to vascular stiffness and calcification in hemodialysis (HD) patients. Methods: We measured fetuin-A, OPG, and HSP70 in 35 healthy controls, 35 patients with stage 3 CKD, 35 patients with stage 4 CKD, and 81 HD patients. Using these data, we studied the association of fetuin-A, OPG, and HSP70 with clinical, biochemical, and vascular measures in HD patients. Results: Levels of OPG and HSP70 were higher and fetuin-A was lower in HD patients than in healthy controls. The cardio-ankle vascular index (CAVI) showed a positive correlation with OPG (r = 0.248, p = 0.040) and the OPG/fetuin-A ratio (r = 0.260, p = 0.031). The ankle-brachial index (ABI) showed a negative correlation with OPG (r = -0.245, p = 0.031) and the OPG/fetuin-A ratio (r = -0.267, p = 0.018). Intima-media thickness (IMT) showed a positive correlation with OPG (r = 0.273, p = 0.014) and the OPG/fetuin-A ratio (r = 0.269, p = 0.015). On stepwise multiple linear regression analyses, only the logarithmic function of the OPG/fetuin-A ratio was independently associated with CAVI (β = 13.325, SE = 6.247, p = 0.038). Conclusions: Our results demonstrate that OPG and the OPG/fetuin-A ratio are correlated with increased vascular stiffness and IMT in HD patients. In addition, the OPG/fetuin-A ratio was independently associated with vascular stiffness in HD patients.