Efficacy and safety of calcium carbonate in normophosphataemic patients with chronic kidney disease Stages 3 and 4

Progress in pharmacotherapy for the treatment of hyperphosphatemia in renal failure

INTRODUCTION

Among the clinical and metabolic complications of progressive chronic kidney disease (CKD), CKD-mineral bone disorder (CKD-MBD) significantly contributes to morbidity and mortality. While overt and persistent hyperphosphatemia is typical of advanced CKD and requires treatment, other abnormalities of calcium/phosphate metabolism begin to occur since the early stages of the disease.

AREAS COVERED

We searched on the PubMed database, without restrictions for language or time range, for randomized clinical trials and meta-analyses investigating phosphate-lowering therapies. The various phosphate binders show different safety profiles and diverse effects on calcium/phosphate metabolism and vascular calcification. The in-depth knowledge of the characteristics of these drugs is crucial to ensure adequate treatment to CKD patients.

EXPERT OPINION

A proper control of serum phosphate can be achieved using phosphate binders. These medications may induce side effects. Moreover, data on their impact on clinical outcomes are partly controversial or scarce, especially for the new generation drugs. Hyperphosphatemia favors cardiovascular disease and increases the risk for CKD progression. These effects are partially mediated by fibroblast growth factor 23 (FGF23), a phosphaturic hormone that raises to maintain normal serum phosphate. Since there are no data supporting the use of phosphate-lowering agents when phosphataemia is normal, a key role is played by reducing dietary phosphate intake with the aim to control serum phosphate and the compensatory FGF23 and parathyroid hormone (PTH) increase.

Mineral and bone disorder and longterm survival in a chronic kidney disease grade 3b-4cohort

Mineral and bone disorder biomarkers 'normal ranges' are controversial. The aim of the study was to evaluate the association between serum calcium (Ca), phosphate (P), intact parathyroid hormone (iPTH), and 25(OH) vitamin D levels and mortality risk, in a chronic kidney disease (CKD) grade (G) 3b-4 cohort. The Uruguayan National Renal Healthcare Program (NRHP-UY) CKD patients' cohort, included between 1 October 2004 and 1 March 2020 and followed-up until 1 March 2021, was analyzed with the Ethics Committee approval. A total of 6473 patients were analyzed: 56% men, median age 73 (65-79) years, 55% on CKD G3b. At the end of the follow-up, 2459 (37.7%) patients had died (6.4/100 patient-year). There were iPTH data on 2013 patients (younger, with lower estimated glomerular filtration rate (eGFR) and lesser comorbidities). By bivariate Cox analysis the lowest death risk was observed with mean Ca between 9.01 and 10.25 mg/dl, P between 2.76 and 4.0 mg/dl, iPTH ≤ 105 pg/ml, and 25(OH) vitamin D >10 ng/ml. The multivariate Cox regression mortality risk adjusted to age, sex, CKD etiology, diabetes, smoking, cardiovascular comorbidity, blood pressure, proteinuria, eGFR, renin-angiotensin system blockers and vitamin D treatments, serum Ca, P, iPTH, and 25(OH) vitamin D (n = 964) showed that a higher mortality risk was associated with p > 4.00 mg/dl (HR 1.668, CI 95%: 1.201-2.317), iPTH >105 pg/ml (HR 1.386, CI 95%: 1.012-1.989), and 25(OH) vitamin D ≤ 10 ng/ml (HR 1.958, CI 95%: 1.238-3.098) and a lower mortality risk with 1,25(OH)2 vitamin D treatment (HR 0.639, CI 95%: 0.451-0.906). These data may contribute to the precise G3b-4 CKD-MBD biomarkers levels definition.

Reversal Of Arterial Disease by modulating Magnesium and Phosphate (ROADMAP-study): rationale and design of a randomized controlled trial assessing the effects of magnesium citrate supplementation and phosphate-binding therapy on arterial stiffness in moderate chronic kidney disease

Background

Arterial stiffness and calcification propensity are associated with high cardiovascular risk and increased mortality in chronic kidney disease (CKD). Both magnesium and phosphate are recognized as modulators of vascular calcification and chronic inflammation, both features of CKD that contribute to arterial stiffness. In this paper, we outline the rationale and design of a randomized controlled trial (RCT) investigating whether 24 weeks of oral magnesium supplementation with or without additional phosphate-binding therapy can improve arterial stiffness and calcification propensity in patients with stage 3–4 CKD.

Methods

In this multi-center, placebo-controlled RCT, a total of 180 participants with an estimated glomerular filtration rate of 15 to 50 ml/min/1.73 m2 without phosphate binder therapy will be recruited. During the 24 weeks intervention, participants will be randomized to one of four intervention groups to receive either magnesium citrate (350 mg elemental magnesium/day) or placebo, with or without the addition of the phosphate binder sucroferric oxyhydroxide (1000 mg/day). Primary outcome of the study is the change of arterial stiffness measured by the carotid-femoral pulse wave velocity over 24 weeks. Secondary outcomes include markers of calcification and inflammation, among others calcification propensity (T50) and high-sensitivity C-reactive protein. As explorative endpoints, repeated 18F-FDG and 18F-NaF PET-scans will be performed in a subset of participants (n = 40). Measurements of primary and secondary endpoints are performed at baseline, 12 and 24 weeks.

Discussion

The combined intervention of magnesium citrate supplementation and phosphate-lowering therapy with sucroferric oxyhydroxide, in stage 3–4 CKD patients without overt hyperphosphatemia, aims to modulate the complex and deregulated mineral metabolism leading to vascular calcification and arterial stiffness and to establish to what extent this is mediated by T50 changes. The results of this combined intervention may contribute to future early interventions for CKD patients to reduce the risk of CVD and mortality.

Trial registration

Netherlands Trial Register, NL8252 (registered December 2019), EU clinical Trial Register 2019-001306-23 (registered November 2019).

The Role of Bone Volume, FGF23 and Sclerostin in Calcifications and Mortality; a Cohort Study in CKD Stage 5 Patients

Chronic kidney disease-mineral and bone disorder has been associated with increasing morbid-mortality. The aim of this study was to determine the prevalence and phenotype of bone disease before transplantation and to correlate FGF23 and sclerostin levels with bone histomorphometry, and study possible associations between FGF23, sclerostin, and bone histomorphometry with cardiovascular disease and mortality. We performed a cross-sectional cohort study of a sample of 84 patients submitted to renal transplant, which were prospectively followed for 12 months. Demographic, clinical, and echocardiographic data were collected, laboratory evaluation, bone biopsy, and X-ray of the pelvis and hands were performed. Patient and graft survival were recorded. We diagnosed low bone turnover in 16 patients (19.5%); high bone turnover in 22 patients (26.8%); osteomalacia in 1 patient (1.2%), and mixed renal osteodystrophy in 3 patients (3.7%). At the end of 12 months, 5 patients had graft failure (5.9%), 4 had a cardiovascular event (4.8%), and 4 died. Age was associated with low remodeling disease, whereas high BALP and phosphorus and low sclerostin with high turnover disease. Sclerostin was a risk factor for isolated low bone volume. High BALP, low phosphorus, and low FGF23 were risk factors for abnormal mineralization. FGF23 appears as an independent factor for severity of vascular calcifications and for cardiovascular events, whereas the presence of valve calcifications was associated with low volume and with turnover deviations. Sclerostin was associated a higher HR for death. Sclerostin and FGF23 seemed to provide higher cardiovascular risk, as well as low bone volume, which associated with extra-osseous calcifications.

Kidney Disease Management in the Hospital Setting: A Focus on Inappropriate Drug Prescriptions in Older Patients

Aging with multimorbidity and polytherapy are the most significant factors that could led to inappropriate prescribing of contraindicated medications in patients with chronic kidney disease (CKD). The aim of this study was to evaluate the prescriptions of contraindicated drugs in older adults in CKD and to identify their associated factors in a hospital context. An observational retrospective study was carried out considering all patients ≥65 years with at least one serum creatinine value recorded into the REPOSI register into 2010-2016 period. The estimated glomerular filtration rate (eGFR) was applied to identify CKD. A descriptive analysis was performed to compare demographic and clinical characteristics; logistic regression models were used to estimate factors of inappropriate and percentage changes of drug use during hospitalization. A total of 4,713 hospitalized patients were recorded, of which 49.8% had an eGFR <60 ml/min/1.73 m²; the 21.9% were in treatment with at least one inappropriate drug at the time of hospital admission with a decrease of 3.0% at discharge (p = 0.010). The probability of using at least one contraindicated drug was significantly higher in patients treated with more several drugs (OR 1.21, 95% CI 1.16-1.25, p <0.001) and with CKD end-stages (G4: 16.90, 11.38-25.12, p < 0.001; G5: 19.38, 11.51-32.64, p < 0.001). Low-dose acetylsalicylic acid was the contraindicated drug mainly used at the time of admission, reducing 1.2% at discharge. An overall increase in therapeutic appropriateness in hospitalized older patients with CKD was observed, despite a small percentage of therapeutic inappropriateness at discharge that underlines the need for a closer collaboration with the pharmacologist to improve the drug management.

Parathyroidectomy is associated with slow progression of vascular calcification in maintenance haemodialysis patients: A propensity score-matched case-control study

Parathyroidectomy has been the mainstay of treatment of severe hyperparathyroidism in patients with kidney failure until the introduction of calcimimetic. Several large observational studies demonstrated the improvement in patient outcomes after parathyroidectomy. The benefit of parathyroidectomy on vascular calcification remains largely unexplored.

AIM

To examine the association between parathyroidectomy and the progression of vascular calcification as well as overall survival in maintenance haemodialysis patients.

METHOD

This is a matched case-control study undertaken between 2012 and 2020. Patients who underwent parathyroidectomy were identified and matched 1:1 to non-parathyroidectomized (non-PTX) haemodialysis patients using propensity score matching method resulting in 120 patients in each arm. Aortic arch calcification (AoAC) score was determined annually in the posteroanterior chest x-ray. The average follow-up period was 38 months.

RESULTS

Baseline demographic, laboratory data and AoAC score were comparable among the two groups of patients. The prevalence of AoAC was 59% in the PTX group and 54% in the non-PTX group (p = .43). Progression of AoAC occurred in 33% in the PTX group and 47% in the non-PTX group (p = .04). Multivariate generalized linear model revealed parathyroidectomy as an independent protective factor [β (95% CI) -1.04 (-1.68, -0.41)] and increased serum calcium as a potentiating factor [β (95% CI) 0.62 (0.25, 0.1)] for progression of AoAC. Linear mixed models revealed an increase in AoAC score in both groups but between group comparisons indicated substantially slower progression in the PTX group. Rapid progression of AoAC was also observed more frequently among non-PTX patients. Death occurred in 7 and 16% in the PTX and non-PTX groups, respectively. Kaplan-Meier survival curve revealed better survival associated with parathyroidectomy (p = .01). More rapid progression of AoAC also correlated with worse survival.

CONCLUSION

Parathyroidectomy was associated with slow progression of vascular calcification in maintenance haemodialysis patients.