Vascular calcification is not an independent predictor of mortality in pre-dialysis adult patients

To the Editor: It has been established that vascular calcification is predictive of mortality in haemodialysis patients [1]. Among pre-dialysis patients, in a study recently published in Nephrol Dial Transplant, Hanada et al. have stated that aortic calcification is associated with an increased risk of cardiovascular events [2]. Furthermore, positive associations between coronary calcification with both cardiovascular events and mortality risk have been reported in the pre-dialysis setting [3]. However, these latter studies were limited by the fact that either mortality was not evaluated [2] or adjustment for possible confounders was not performed [3]. To further investigate this issue, we performed a prospective study of a cohort of 92 pre-dialysis patients (mean ± SD age: 68 ± 12 years) at different chronic kidney disease (CKD) stages (12.5% at stage 2, 37.5% at stage 3, 41% at stage 4 and 9% at stage 5). Abdominal aortic and coronary calcifications were evaluated by multi-slice spiral computed tomography. Eighteen patients died during the follow-up period (mean ± SD duration: 794 ± 244 days). In crude survival analyses, a coronary calcification score >259 AU and an aortic calcification score >1.53 predicted overall mortality (P = 0.01 and P = 0.04, respectively). These cut-off values were estimated by maximizing sensitivity and specificity in ROC curves for predicting mortality. However, the associations were no longer statistically significant after adjustment for age in multivariate Cox regression analyses. In conclusion, vascular calcification was not an independent predictor of mortality in pre-dialysis adult patients. Other factors such as endothelial dysfunction [4] may prevail over vascular calcification in early-stage CKD. Further investigation in a prospective study with a larger sample size is required to address this issue. Conflict of interest statement. None declared.