The Vessels-Bone Axis: Iliac Artery Calcifications, Vertebral Fractures and Vitamin K from VIKI Study

Real-world usage of Chronic Kidney Disease - Mineral Bone Disorder (CKD-MBD) biomarkers in nephrology practices

Background

Chronic kidney disease mineral bone disorder (CKD-MBD) is a condition characterized by alterations of calcium, phosphate, parathyroid hormone (PTH), and fibroblast growth factor 23 (FGF-23) metabolism that in turn promote bone disorders, vascular calcifications, and increase cardiovascular (CV) risk. Nephrologists' awareness of diagnostic, prognostic, and therapeutic tools to manage CKD-MBD plays a primary role in adequately preventing and managing this condition in clinical practice.

Methods

A national survey (composed of 15 closed questions) was launched to inquire about the use of bone biomarkers in the management of CKD-MBD patients by nephrologists and to gain knowledge about the implementation of guideline recommendations in clinical practice.

Results

One hundred and six Italian nephrologists participated in the survey for an overall response rate of about 10%. Nephrologists indicated that the laboratories of their hospitals were able to satisfy request of ionized calcium levels, 105 (99.1%) of both PTH and alkaline phosphatase (ALP), 100 (94.3%) of 25(OH)D, and 61 (57.5%) of 1.25(OH)2D; while most laboratories did not support the requests of biomarkers such as FGF-23 (intact: 88.7% and c-terminal: 93.4%), Klotho (95.3%; soluble form: 97.2%), tartrate-resistant acid phosphatase 5b (TRAP-5b) (92.5%), C-terminal telopeptide (CTX) (71.7%), and pro-collagen type 1 N-terminal pro-peptide (P1NP) (88.7%). As interesting data regarding Italian nephrologists' behavior to start treatment of secondary hyperparathyroidism (sHPT), the majority of clinicians used KDOQI guidelines (n = 55, 51.9%). In contrast, only 40 nephrologists (37.7%) relied on KDIGO guidelines, which recommended referring to values of PTH between two and nine times the upper limit of the normal range.

Conclusion

Results point out a marked heterogeneity in the management of CKD-MBD by clinicians as well as a suboptimal implementation of guidelines in Italian clinical practice.

Cardiovascular Safety and Effectiveness of Bisphosphonates: From Intervention Trials to Real-Life Data

Both osteoporosis with related fragility fractures and cardiovascular diseases are rapidly outspreading worldwide. Since they are often coexistent in elderly patients and may be related to possible common pathogenetic mechanisms, the possible reciprocal effects of drugs employed to treat these diseases have to be considered in clinical practice. Bisphosphonates, the agents most largely employed to decrease bone fragility, have been shown to be overall safe with respect to cardiovascular diseases and even capable of reducing cardiovascular morbidity in some settings, as mainly shown by real life studies. No randomized controlled trials with cardiovascular outcomes as primary endpoints are available. While contradictory results have emerged about a possible BSP-mediated reduction of overall mortality, it is undeniable that these drugs can be employed safely in patients with high fracture risk, since no increased mortality has ever been demonstrated. Although partial reassurance has emerged from meta-analysis assessing the risk of cardiac arrhythmias during bisphosphonates treatment, caution is warranted in administering this class of drugs to patients at risk for atrial fibrillation, possibly preferring other antiresorptives or anabolics, according to osteoporosis guidelines. This paper focuses on the complex relationship between bisphosphonates use and cardiovascular disease and possible co-management issues.

Prevalence and Correlates of Cardiovascular Calcification and Its Prognostic Effects Among Patients With Chronic Kidney Disease: Results From the C-STRIDE Study

Background and Aims: The purpose of this study was to identify the characteristics and risk factors for cardiovascular calcification, and its relationship to prognosis, in patients with chronic kidney disease (CKD) stages 1–4.

Methods: Cardiovascular calcification was evaluated at baseline by lateral abdominal radiography to detect abdominal aortic calcifications (AAC), and by echocardiogram to detect cardiac valvular calcifications (CVC), respectively. Demographic and laboratory data were collected and analyzed. Univariate and multivariable logistic regression model was used to explore the factors associated with the indicators of cardiovascular calcification, while Cox proportional hazards regression was used to examine the association between AAC/CVC and incidence of cardiovascular events and all-cause mortality.

Results: A subgroup of 2,235 patients with measurement of AAC in the C-STRIDE study and a subgroup of 2,756 patients with CVC were included in the analysis. AAC was present in 206 patients (9.22%) and CVC was present in 163 patients (5.91%). Age, gender, history of cardiovascular diseases, smoking, hypertension, diabetes, levels of hemoglobin, low-density lipoprotein cholesterol, and uric acid were associated with prevalence of AAC, while only age, history of cardiovascular diseases, levels of serum albumin and low-density lipoprotein cholesterol were associated with prevalence of CVC (all p < 0.05).Survival analyses showed that cardiovascular events and all-cause mortality were significantly greater in patients with AACor with CVC (all p-values for log-rank tests <0.05). After adjustment for age, sex and estimated glomerular filtration rate (eGFR), AAC was associated with increased risk of all-cause mortality (hazard ratio = 1.67[95% confidence interval: 0.99, 2.79]), while CVC associated with that of cardiovascular events only among patients with comparatively normal eGFR (≥45 ml/min/1.73m²) (hazard ratio = 1.99 [0.98, 4.03]).

Conclusion: Demographic and traditional cardiovascular risk factors were associated with cardiovascular calcification, especially AAC. AAC may be associated with risk of death for patients CKD of any severity, while CVC as a possible risk factor for cardiovascular disease only among those with mild to moderate CKD. Assessments of vascular calcification are need to be advanced to patients in the early and middle stages of chronic kidney disease and to initiate appropriate preventive measures earlier.

Vitamin K Supplementation for Prevention of Vascular Calcification in Chronic Kidney Disease Patients: Are We There Yet?

Chronic Kidney Disease (CKD) patients are at high risk of presenting with arterial calcification or stiffness, which confers increased cardiovascular mortality and morbidity. In recent years, it has become evident that VC is an active process regulated by various molecules that may act as inhibitors of vessel mineralization. Matrix Gla Protein (MGP), one the most powerful naturally occurring inhibitors of arterial calcification, requires vitamin K as a co-factor in order to undergo post-translational γ-carboxylation and phosphrorylation and become biologically active. The inactive form of MGP (dephosphorylated, uncarboxylated dp-ucMGP) reflects vitamin K deficiency and has been repeatedly associated with surrogate markers of VC, stiffness, and cardiovascular outcomes in CKD populations. As CKD is a state of progressive vitamin K depletion and VC, research has focused on clinical trials aiming to investigate the possible beneficial effects of vitamin K in CKD and dialysis patients. In this study, we aim to review the current evidence regarding vitamin K supplementation in uremic patients.