Effects of Lowering Dialysate Calcium Concentration on Carotid Intima-Media Thickness and Aortic Stiffness in Patients Undergoing Maintenance Hemodialysis: A Prospective Study

Background and Aim: The study aimed to prospectively evaluate the effects of lowering the dialysate calcium concentration (DCa) to 1.25 mmol/l on Chinese patients undergoing maintenance hemodialysis (MHD), which are largely unknown to date. Methods: A singer-center, prospective, randomized trial was conducted for 2 years. The DCa in one group was decreased from 1.5 to 1.25 mmol/l but there was no change in the other group. The clinical outcomes, biochemical parameters, medicine treatments and markers of vascular change were compared among the 2 groups at different time intervals. Results: At baseline, the groups were similar with respect to serum levels of calcium, phosphorus, intact parathyroid hormone and fibroblast growth factor-23 as well as carotid intima-media thickness (cIMT) and carotid-femoral pulse wave velocity (cf-PWV). It was found that the serum phosphorus concentration in the lower DCa group had decreased markedly at 2-year follow-up (0-month: 7.13 ± 1.56 mg/dl; 24-month: 5.92 ± 1.73 mg/dl; p = 0.005). Serum calcium (p = 0.018), cIMT (p = 0.029) and cf-PWV (p = 0.024) in DCa 1.25 group were significantly lower than those in 1.5 group at the 24-month visit. Kaplan-Meier curve revealed that patients in DCa 1.25 group had a better rate of survival. In the multivariate Cox regression analysis, cIMT (HR 1.010; 95% CI 1.002-1.217; p = 0.015) and cf-PWV (HR 1.265; 95% CI 1.022-1.567; p = 0.031) were potential risk factors for mortality in those patients. Importantly, we showed that the average change in these 2 risk variables were both associated with the average change in levels of serum calcium and phosphorus. Conclusion: Our results indicate that lowering DCa to 1.25 mmol/l may be suitable for the MHD patients in our unit.