Risk factors of the progression of abdominal aortic calcification in patients on chronic haemodialysis

Background. Vascular calcification is an independent determinant of cardiovascular events in maintenance haemodialysis (HD) patients. It is not known whether acute changes of the serum calcium concentration before and after HD (ACa) are associated with the development of aortic calcification. Methods. We enrolled 71 patients dialysed with a dialysate with 3.0 mEq/l calcium and determined their aortic calcification index (ACI) by abdominal computed tomography twice at an interval of 3 years. To identify the factors contributing to the rate of progression of aortic calcification, we analysed the average values for clinical and laboratory data obtained between the first and second evaluations of ACI. Results. The second ACI (mean +/- SD: 80.2 +/- 63.9) was significantly greater than the first ACI (61.0 +/- 61.0) after an interval of 35.8 +/- 4.2 months. The annualized change of ACI (Delta ACI/year) was significantly and directly associated with the Delta Ca and C-reactive protein (CRP) (both P < 0.001, P for trend). Stepwise multivariate regression analysis revealed that Delta ACI/ year was positively and independently associated with CRP, presence of diabetes mellitus and Delta Ca/ but negatively associated with a premenopausal status in women. Similarly, Delta Ca was positively and independently associated with Delta ACI/year and the ultrafiltration rate, but was negatively associated with pre-HD Ca. Conclusion. The increase of serum calcium after HD was related to the rate of progression of aortic calcification. Excess calcium is transferred into patients on HD when using a dialysate of 3.0 mEq/l calcium. This may be a risk factor for the development of vascular calcification.