Vascular calcification in patients with nondialysis CKD over 3 years

Abstract

Background and objectives: Vascular calcification (VC) is common in CKD, but little is known about its prognostic effect on patients with nondialysis CKD. The prevalence of VC and its ability to predict death, time to hospitalization, and renal progression were assessed.

Design, setting, participants, & measurements: The Study of Mineral and Bone Disorders in CKD in Spain is a prospective, observational, 3-year follow-up study of 742 patients with nondialysis CKD stages 3-5 from 39 centers in Spain from April to May 2009. VC was assessed using Adragao (AS; x-ray pelvis and hands) and Kauppila (KS; x-ray lateral lumbar spine) scores from 572 and 568 patients, respectively. The primary end point was death. Secondary outcomes were hospital admissions and appearance of a combined renal end point (beginning of dialysis or drop >30% in eGFR). Factors related to VC were assessed by logistic regression analysis. Survival analysis was assessed by Cox proportional models.

Results: VC was present in 79% of patients and prominent in 47% (AS≥3 or KS>6). Age (odds ratio [OR], 1.05; 95% confidence interval [95% CI], 1.02 to 1.07; P<0.001), phosphorous (OR, 1.68; 95% CI, 1.28 to 2.20; P<0.001), and diabetes (OR, 2.11; 95% CI, 1.32 to 3.35; P=0.002) were independently related to AS≥3. After a median follow-up of 35 months (interquartile range=17-36), there were 70 deaths (10%). After multivariate adjustment for age, smoking, diabetes, comorbidity, renal function, and level of phosphorous, AS≥3 but not KS>6 was independently associated with all-cause (hazard ratio [HR], 2.07; 95% CI, 1.07 to 4.01; P=0.03) and cardiovascular (HR, 3.46; 95% CI, 1.27 to 9.45; P=0.02) mortality as well as a shorter hospitalization event-free period (HR, 1.14; 95% CI, 1.06 to 1.22; P<0.001). VC did not predict renal progression.

Conclusions: VC is highly prevalent in patients with CKD. VC assessment using AS independently predicts death and time to hospitalization. Therefore, it could be a useful index to identify patients with CKD at high risk of death and morbidity as previously reported in patients on dialysis.

Keywords: cardiovascular disease; chronic renal disease; metabolism; mineral; vascular calcification.

Figure 1.

Proportion of patients with Kauppila score >6, Adragao score ≥3, and vascular calcification of the radial and cubital arteries (Adragao Index-hands) ≥1 according to the stages of CKD.

Figure 2.

Vascular calcification scores in individual patients in relation to their age.

Figure 3.

Curves of overall survival and cardiovascular death of patients with CKD according to the presence of Kauppila score (KS) ≤6 or >6 ([A] overall survival; [B] cardiovascular survival), Adragao score (AS)<3 or ≥3 ([C] overall survival; [D] cardiovascular survival), and AS (only hands; AS-hands) =0 or ≥1 ([E] overall survival; [F] cardiovascular survival).

Figure 4.

All-cause and cardiovascular hospitalization event–free periods in patients with CKD according to the presence of KS ≤6 or >6 ([A] all–cause hospitalization event–free period; [B] cardiovascular hospitalization event–free period), AS <3 or ≥3 ([C] all-cause hospitalization event–free period; [D] cardiovascular hospitalization event–free period), and AS (only hands; AS-hands) =0 or ≥1 ([E] all-cause hospitalization event–free period; [F] cardiovascular hospitalization event–free period).