Short-term treatment with sevelamer increases serum fetuin-a concentration and improves endothelial dysfunction in chronic kidney disease stage 4 patients

Effect of Lanthanum Carbonate on Serum Phosphate, Oxidative Stress, and Vascular Dysfunction in CKD: A Mechanistic Randomized Controlled Trial

Key Points

A key mechanism contributing to vascular dysfunction in CKD is increased oxidative stress. Lanthanum carbonate did not discernibly affect vascular endothelial function, arterial stiffness, or markers of endothelial oxidative stress.

Background

Vascular endothelial dysfunction and arterial stiffness are common in CKD and independently predict cardiovascular disease. Elevated serum phosphorus, even within the normal range, associates with cardiovascular disease and mortality in CKD. Excess phosphorus may increase oxidative stress leading to vascular dysfunction.

Methods

This is a randomized double-blind trial in which we compared lanthanum carbonate, a noncalcium phosphate binder, with placebo on vascular function and endothelial and circulating measures of oxidative stress and inflammation in 54 participants with CKD 3b–4 and normal phosphorus levels. Primary end points were change in brachial artery flow-mediated dilation (FMDBA) and carotid-to-femoral pulse-wave velocity (cfPWV) at 12 weeks. Mechanistic end points were changes from baseline in FMDBA after ascorbic acid infusion and circulating and endothelial markers of oxidative stress and inflammation.

Results

The age was 65±8 years and eGFR was 38±14 ml/min per 1.73 m2. At 12 weeks, serum phosphorus did not change with lanthanum (3.44±0.47 versus 3.44±0.52 mg/dl; P = 0.94) but tended to increase with placebo (3.42±0.80 versus 3.74±1.26 mg/dl; P = 0.09). FMDBA and cfPWV did not change from baseline in either group: FMDBA lanthanum 3.13%±2.87% to 2.73%±2.48% versus placebo 3.74%±2.86% to 3.09%±2.49% (P = 0.67); CfPWV lanthanum 1214±394 to 1216±322 cm/s versus placebo 993±289 to 977±254 cm/s (P = 0.77). Ascorbic acid infusion to inhibit oxidative stress did not differentially affect FMDBA. Circulating and endothelial markers of oxidative stress and inflammation did not differ between groups.

Conclusions

Lanthanum carbonate did not discernibly affect vascular endothelial function, arterial stiffness, or markers of endothelial oxidative stress among participants with CKD 3b–4 and normophosphatemia.

The Relationship of Fetuin-A with Coronary Calcification, Carotid Atherosclerosis, and Mortality Risk in Non-Dialysis Chronic Kidney Disease

Objective

This study investigated the relationship of fetuin-A with coronary calcification, carotid atherosclerosis, and mortality risk in non-dialysis chronic kidney disease (CKD).

Methods

The study included 135 adult patients with CKD at stages 3-5, who were divided into coronary artery calcification (CAC) and non-CAC groups. We excluded current smokers and individuals with diabetes mellitus, inflammatory conditions, liver diseases, acute kidney failure, chronic hemodialysis, and cancer. We conducted kidney function tests, complete blood counts, and measured serum levels of fetuin-A, tumor necrosis factor-alpha (TNF-α), high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), total cholesterol (TC), total triglycerides (TG), high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol. Cardiac spiral computed tomography was used to calculate the CAC score, employing the Agatston method. Carotid ultrasonography was performed to assess carotid intima-media thickness (CIMT) and to detect the presence of plaques.

Results

CAC patients had considerably higher levels of TNF-α (p<0.001), IL-6 (p<0.001), hs-CRP (p=0.006), TC, TG, parathyroid hormone (PTH) (p<0.001) and phosphorus (p<0.001) than non-CAC patients. They also had significantly lower levels of fetuin-A (p<0.001). Fetuin-A was considerably lower in CKD subgroups as CKD progressed. Fetuin-A (p=0.046), age (p=0.009), TNF-α (p=0.027), IL-6 (p=0.005), TG (p=0.002), PTH (p=0.002), and phosphorus (p=0.004) were significant predictors of CAC. CAC and fetuin-A were strong predictors of all-cause mortality and cardiovascular (CV) mortality. Fetuin-A was a significant predictor of CIMT (p=0.045).

Conclusion

Fetuin-A reliably predicted CAC and CIMT. Fetuin-A and CAC emerged as significant risk factors for all-cause and CV mortality in non-dialysis CKD.

Pathophysiology and Clinical Impacts of Chronic Kidney Disease on Coronary Artery Calcification

The global prevalence of chronic kidney disease (CKD) has increased in recent years. Adverse cardiovascular events have become the main cause of life-threatening events in patients with CKD, and vascular calcification is a risk factor for cardiovascular disease. Vascular calcification, especially coronary artery calcification, is more prevalent, severe, rapidly progressive, and harmful in patients with CKD. Some features and risk factors are unique to vascular calcification in patients with CKD; the formation of vascular calcification is not only influenced by the phenotypic transformation of vascular smooth muscle cells, but also by electrolyte and endocrine dysfunction, uremic toxin accumulation, and other novel factors. The study on the mechanism of vascular calcification in patients with renal insufficiency can provide a basis and new target for the prevention and treatment of this disease. This review aims to illustrate the impact of CKD on vascular calcification and to discuss the recent research data on the pathogenesis and factors involved in vascular calcification, mainly focusing on coronary artery calcification, in patients with CKD.

Hyperphosphatemia and its relationship with blood pressure, vasoconstriction, and endothelial cell dysfunction in hypertensive hemodialysis patients

Background

Hyperphosphatemia occurs frequently in end-stage renal disease patients on hemodialysis and is associated with increased mortality. Hyperphosphatemia contributes to vascular calcification in these patients, but there is emerging evidence that it is also associated with endothelial cell dysfunction.

Methods

We conducted a cross-sectional study in hypertensive hemodialysis patients. We obtained pre-hemodialysis measurements of total peripheral resistance index (TPRI, non-invasive cardiac output monitor) and plasma levels of endothelin-1 (ET-1) and asymmetric dimethylarginine (ADMA). We ascertained the routine peridialytic blood pressure (BP) measurements from that treatment and the most recent pre-hemodialysis serum phosphate levels. We used generalized linear regression analyses to determine independent associations between serum phosphate with BP, TPRI, ET-1, and ADMA while controlling for demographic variables, parathyroid hormone (PTH), and interdialytic weight gain.

Results

There were 54 patients analyzed. Mean pre-HD supine and seated systolic and diastolic BP were 164 (27), 158 (21), 91.5 (17), and 86.1 (16) mmHg. Mean serum phosphate was 5.89 (1.8) mg/dL. There were significant correlations between phosphate with all pre-hemodialysis BP measurements (r = 0.3, p = .04; r = 0.4, p = .002; r = 0.5, p < .0001; and r = 0.5, p = .0003.) The correlations with phosphate and TPRI, ET-1, and ADMA were 0.3 (p = .01), 0.4 (p = .007), and 0.3 (p = .04). In our final linear regression analyses controlling for baseline characteristics, PTH, and interdialytic weight gain, independent associations between phosphate with pre-hemodialysis diastolic BP, TPRI, and ET-1 were retained (β = 4.33, p = .0002; log transformed β = 0.05, p = .005; reciprocal transformed β = -0.03, p = .047).

Conclusions

Serum phosphate concentration is independently associated with higher pre-HD BP, vasoconstriction, and markers of endothelial cell dysfunction. These findings demonstrate an additional negative impact of hyperphosphatemia on cardiovascular health beyond vascular calcification.

Trial registration

The study was part of a registered clinical trial, NCT01862497 (May 24, 2013).

The structure, biosynthesis, and biological roles of fetuin-A: A review

Fetuin-A is a heterodimeric plasma glycoprotein containing an A-chain of 282 amino acids and a B-chain of 27 amino acid residues linked by a single inter-disulfide bond. It is predominantly expressed in embryonic cells and adult hepatocytes, and to a lesser extent in adipocytes and monocytes. Fetuin-A binds with a plethora of receptors and exhibits multifaceted physiological and pathological functions. It is involved in the regulation of calcium metabolism, osteogenesis, and the insulin signaling pathway. It also acts as an ectopic calcification inhibitor, protease inhibitor, inflammatory mediator, anti-inflammatory partner, atherogenic factor, and adipogenic factor, among other several moonlighting functions. Fetuin-A has also been demonstrated to play a crucial role in the pathogenesis of several disorders. This review mainly focuses on the structure, synthesis, and biological roles of fetuin-A. Information was gathered manually from various journals via electronic searches using PubMed, Google Scholar, HINARI, and Cochrane Library from inception to 2022. Studies written in English and cohort, case-control, cross-sectional, or experimental studies were considered in the review, otherwise excluded.

Causal association pathways between fetuin-A and kidney function: a mediation analysis

Objective

Body mass index (BMI), uric acid, diabetes mellitus, and hypertension are risk factors for reduced kidney function and are associated with fetuin-A levels, but their causal pathways remain unclear. The objective of this study was to investigate this knowledge gap.

Methods

A repeated cross-sectional design was used to assess causal pathway effects of fetuin-A on the estimated glomerular filtration rate (eGFR), which is mediated through BMI, uric acid, diabetes mellitus, and hypertension.

Results

Among 2305 participants, the mean eGFR at baseline decreased from 98.7 ± 23.6 mL/minute/1.73 m² in 2009 to 92.4 ± 22.9 mL/minute/1.73 m² in 2014. Fetuin-A was significantly associated with eGFR , suggesting that increasing fetuin-A levels predict a decrease in eGFR. Additionally, the indirect effect of fetuin-A on eGFR, as assessed through BMI, was also significant. The effects of fetuin-A on eGFR through other mediation pathways showed variable results.

Conclusions

Our study revealed a possible role of fetuin-A in the etiology of declining renal function through mediating body mass index, uric acid, diabetes mellitus, and hypertension via complex causal pathways. Further studies to clarify these mediated effects are recommended.

Systematic review and meta-analysis of potential pleiotropic effects of sevelamer in chronic kidney disease: Beyond phosphate control

Sevelamer, has been shown to have many pleiotropic actions on lipid panel, various inflammatory markers, and blood glucose levels in chronic kidney disease patients. We conducted a systematic review and meta-analysis to compare these pleiotropic effects of sevelamer to other phosphate binders used in chronic kidney disease patients. The relevant randomized controlled trials published from 1 January 2001 to 31 November 2019 on the following databases: Cochrane Central Register of Controlled Trials published in The Cochrane Library, PubMed, Scopus and Google Scholar were identified. All the included studies were independently assessed for eligibility and risk of bias. The modified data extraction form of Cochrane was used. This review included 44 studies for qualitative analysis and 28 reports for quantitative analysis. A meta-analysis of three studies (n = 180) showed that glycated haemoglobin had significantly decreased in sevelamer-treated patients (MD: 0.5%; p = <.001). Compared with calcium-based phosphate binders, sevelamer showed a significant reduction in low-density lipoprotein (MD: -19.43 mg/dL; p = <.001) and total cholesterol (MD: -19.98 mg/dL; p < .001). A significant increase in high-density lipoprotein (MD: 1.29 mg/dL; p = .05) was also prominent in sevelamer treated patients. However, we were not able to observe a significant change in other biochemical parameters such as TG, CRP, hs-CRP, FGF-23, IL-6 and albumin as, no statistically significant difference was observed.

The impact of phosphate lowering agents on clinical and laboratory outcomes in chronic kidney disease patients: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Besides reducing hyperphosphatemia in chronic kidney disease (CKD) patients, phosphate lowering agents might provide beneficial effects on clinical and laboratory parameters. This meta-analysis was conducted to comprehensively examine the impact of all phosphate lowering agents on various aspects of clinical and laboratory outcomes in CKD patients.

METHOD

A systematic literature search was performed in MEDLINE, Scopus, and the Cochrane Register of Controlled Trials until July 2020 to identify randomized controlled trials (RCTs) which compared the effects of each phosphate lowering agent with controls, comprising placebo and all other phosphate lowering agents. Various clinical and laboratory outcomes were analyzed. Random effects model was used to compute the standardized mean difference for continuous variables and the risk ratio (RR) for binary variables.

RESULTS

This meta-analysis included 127 RCTs with 20,215 patients. Sevelamer and lanthanum significantly reduced all-cause mortality (RR 0.610, 95% CI 0.401-0.929 and 0.467, 95% CI 0.337-0.647, respectively) but not cardiovascular (CV) mortality or CV events. Hospitalization rates were significantly diminished by sevelamer (RR 0.527; 95% CI 0.308-0.902). Certain phosphate lowering agents improved biochemical parameters including serum phosphate, calcium, coronary artery calcium scores, fibroblast growth factor-23, bone biomarkers, and lipid profiles. Intact parathyroid hormone and bone mineral density were not significantly changed.

CONCLUSIONS

In addition to decreasing serum phosphate levels, various beneficial effects on clinical and laboratory parameters of phosphate lowering agents might play potential roles in diminishing morbidity and mortality in CKD patients.

Vascular calcification of chronic kidney disease: A brief review

Vascular calcification (VC) is highly prevalent among patients with chronic kidney disease (CKD). There is growing evidence that there is more underlying this condition than the histological presentation of atherosclerotic plaque and arteriosclerosis and that the risk of cardiovascular disease in the context of CKD might be explained by the presence of VC. While VC has been observed in the absence of overt abnormal mineral metabolism, this association is coupled to abnormal homeostasis of minerals in patients with CKD, due to hyperphosphatemia and hypercalcemia. Furthermore, recent studies have shown that the differentiation of vascular smooth muscle cells into an osteogenic phenotype is highly regulated by pro-calcifying and anti-calcifying factors. There are several imaging modalities currently used in clinical practice to evaluate the extent and severity of VC; each has different advantages and limitations. Although there is no universally accepted method for the treatment of VC, there is growing evidence of the beneficial effects of medical therapy for the condition. This study discusses the mechanism underlying VC, imaging modalities used for evaluation of the condition, and possible treatments.

The Novel Phosphate and Bile Acid Sequestrant Polymer SAR442357 Delays Disease Progression in a Rat Model of Diabetic Nephropathy

As a gut-restricted, nonabsorbed therapy, polymeric bile acid sequestrants (BAS) play an important role in managing hyperlipidemia and hyperglycemia. Similarly, nonabsorbable sequestrants of dietary phosphate have been used for the management of hyperphosphatemia in end-stage renal disease. To evaluate the potential utility of such polymer sequestrants to treat type 2 diabetes (T2D) and its associated renal and cardiovascular complications, we synthesized a novel polymeric sequestrant, SAR442357, possessing optimized bile acid (BA) and phosphate sequestration characteristics. Long-term treatment of T2D obese ^cZucker fatty/Spontaneously hypertensive heart failure F1 hybrid (ZSF1) with SAR442357 resulted in enhanced sequestration of BAs and phosphate in the gut, improved glycemic control, lowering of serum cholesterol, and attenuation of diabetic kidney disease (DKD) progression. In comparison, colesevelam, a BAS with poor phosphate binding properties, did not prevent DKD progression, whereas losartan, an angiotensin II receptor blocker that is widely used to treat DKD, showed no effect on hyperglycemia. Analysis of hepatic gene expression levels of the animals treated with SAR442357 revealed upregulation of genes responsible for the biosynthesis of cholesterol and BAs, providing clear evidence of target engagement and mode of action of the new sequestrant. Additional hepatic gene expression pathway changes were indicative of an interruption of the enterohepatic BA cycle. Histopathological analysis of ZSF1 rat kidneys treated with SAR442357 further supported its nephroprotective properties. Collectively, these findings reveal the pharmacological benefit of simultaneous sequestration of BAs and phosphate in treating T2D and its associated comorbidities and cardiovascular complications. SIGNIFICANCE STATEMENT: A new nonabsorbed polymeric sequestrant with optimum phosphate and bile salt sequestration properties was developed as a treatment option for DKD. The new polymeric sequestrant offered combined pharmacological benefits including glucose regulation, lipid lowering, and attenuation of DKD progression in a single therapeutic agent.

How do Uremic Toxins Affect the Endothelium?

Uremic toxins can induce endothelial dysfunction in patients with chronic kidney disease (CKD). Indeed, the structure of the endothelial monolayer is damaged in CKD, and studies have shown that the uremic toxins contribute to the loss of cell–cell junctions, increasing permeability. Membrane proteins, such as transporters and receptors, can mediate the interaction between uremic toxins and endothelial cells. In these cells, uremic toxins induce oxidative stress and activation of signaling pathways, including the aryl hydrocarbon receptor (AhR), nuclear factor kappa B (NF-κB), and mitogen-activated protein kinase (MAPK) pathways. The activation of these pathways leads to overexpression of proinflammatory (e.g., monocyte chemoattractant protein-1, E-selectin) and prothrombotic (e.g., tissue factor) proteins. Uremic toxins also induce the formation of endothelial microparticles (EMPs), which can lead to the activation and dysfunction of other cells, and modulate the expression of microRNAs that have an important role in the regulation of cellular processes. The resulting endothelial dysfunction contributes to the pathogenesis of cardiovascular diseases, such as atherosclerosis and thrombotic events. Therefore, uremic toxins as well as the pathways they modulated may be potential targets for therapies in order to improve treatment for patients with CKD.

Uremic Toxins and Vascular Dysfunction

Vascular dysfunction is an essential element found in many cardiovascular pathologies and in pathologies that have a cardiovascular impact such as chronic kidney disease (CKD). Alteration of vasomotricity is due to an imbalance between the production of relaxing and contracting factors. In addition to becoming a determining factor in pathophysiological alterations, vascular dysfunction constitutes the first step in the development of atherosclerosis plaques or vascular calcifications. In patients with CKD, alteration of vasomotricity tends to emerge as being a new, less conventional, risk factor. CKD is characterized by the accumulation of uremic toxins (UTs) such as phosphate, para-cresyl sulfate, indoxyl sulfate, and FGF23 and, consequently, the deleterious role of UTs on vascular dysfunction has been explored. This accumulation of UTs is associated with systemic alterations including inflammation, oxidative stress, and the decrease of nitric oxide production. The present review proposes to summarize our current knowledge of the mechanisms by which UTs induce vascular dysfunction.

Chronic inflammation in end-stage renal disease and dialysis

Under normal conditions, inflammation is a protective and physiological response to various harmful stimuli. However, in several chronic debilitating disorders, such as chronic kidney disease, inflammation becomes maladaptive, uncontrolled and persistent. Systemic persistent inflammation has, for almost 20 years, been recognized as a major contributor to the uraemic phenotype (such as cardiovascular disease, protein energy wasting, depression, osteoporosis and frailty), and a predictor of cardiovascular and total mortality. Since inflammation is mechanistically related to several ageing processes (inflammageing), it may be a major driver of a progeric phenotype in the uraemic milieu. Inflammation is likely the consequence of a multifactorial aetiology and interacts with a number of factors that emerge when uraemic toxins accumulate. Beside interventions aiming to decrease the production of inflammatory molecules in the uraemic milieu, novel strategies to increase the removal of large middle molecules, such as expanded haemodialysis, may be an opportunity to decrease the inflammatory allostatic load associated with retention of middle molecular weight uraemic toxins.

Does the Administration of Sevelamer or Nicotinamide Modify Uremic Toxins or Endotoxemia in Chronic Hemodialysis Patients?

BACKGROUND

Hyperphosphatemia control is a major issue in hemodialysis patients. Both sevelamer and nicotinamide are prescribed for this purpose. In addition, they exert pleiotropic effects such as an improvement of inflammatory status and potentially enhanced clearance of uremic toxins. In the present secondary analysis of the NICOREN trial, we investigated the impact of sevelamer and nicotinamide on uremic toxins, toxin precursors, and endotoxemia in chronic hemodialysis patients.

METHODS

Circulating uremic toxins (including phenylacetylglutamine, trimethylamine-N-oxide, p-cresyl sulfate, indoxyl sulfate, kynurenine, hippuric acid, indole-3-acetic acid, 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid, kynurenic acid, and p-cresyl glucuronide) and precursors were measured by ultra-performance liquid chromatography-tandem mass spectrometry, and urea, uric acid, phosphate, C-reactive protein, and intact parathyroid hormone by routine biochemistry methods. Serum endotoxin (evaluated by lipopolysaccharide levels) and C-terminal fibroblast growth factor-23 levels were measured using enzyme-linked immunosorbent assay kits.

RESULTS

One hundred hemodialysis patients were randomized to receive either nicotinamide or sevelamer treatment. Among them, 63% were male, mean (± standard deviation) age was 65 ± 14 years, 47% had diabetes mellitus, and 51% had a history of cardiovascular disease. In the sevelamer group, but not the nicotinamide group, serum levels of urea, uric acid, and fibroblast growth factor-23 were significantly reduced after 6 months of treatment. The other circulating uremic toxins and toxin precursors remained unchanged in response to either phosphate-lowering agent. Sevelamer treatment led to a marked decrease in serum lipopolysaccharide (p < 0.001) whereas nicotinamide treatment induced an only modest decrease of borderline significance (p = 0.057). There was no change in C-reactive protein levels.

CONCLUSION

In contrast to sevelamer, nicotinamide did not reduce circulating levels of low-molecular-weight uremic toxins other than phosphate, and neither agent reduced circulating uremic toxins of high-molecular-weight or protein-bound toxins. Sevelamer, but not nicotinamide, reduced serum endotoxin levels. Despite no change in serum C-reactive protein, the endotoxin-lowering effect of sevelamer may help to attenuate the inflammatory status of patients with chronic kidney disease.

Effect of Treatment of Metabolic Acidosis on Vascular Endothelial Function in Patients with CKD: A Pilot Randomized Cross-Over Study

BACKGROUND AND OBJECTIVES

We examined the effect of alkali replacement for metabolic acidosis on vascular endothelial function in patients with CKD.

METHODS

We performed a pilot, prospective, open-label 14-week crossover study examining the effect of oral sodium bicarbonate treatment on vascular function in 20 patients with an eGFR of 15-44 ml/min per 1.73 m2 with low serum bicarbonate levels (16-21 mEq/L). Each period was 6 weeks in duration with a 2-week washout period in between. Patients were treated to goal serum bicarbonate of ≥23 mEq/L. The primary end point was change in brachial artery flow-mediated dilation (FMD) between treatment and control conditions. Secondary end points included changes in markers of inflammation, bone turnover, mineral metabolism, and calcification.

RESULTS

Eighteen patients completed the study and were included in the primary efficacy analysis. The mean (SD) age and eGFR were 59 (12) years and 26 (8) ml/min per 1.73 m2, respectively. Serum bicarbonate increased significantly with sodium bicarbonate treatment (+2.7±2.9 mEq/L, P≤0.001), whereas there was no change in bicarbonate levels in the control group. FMD significantly improved after sodium bicarbonate therapy (mean±SD, FMD baseline: 4.1%±4.1%; 6 weeks: 5.2%±2.9%; P=0.04) There was no significant change in FMD in the control group (mean±SD, FMD baseline: 4.6%±3.1%; 6 weeks: 4.1%±3.4%; P=0.20). Compared with control, sodium bicarbonate treatment resulted in a significant increase in FMD (mean, 1.8%; 95% confidence interval, 0.3 to 3.3; P=0.02). There was no significant change in bone markers or serum calcification propensity with treatment. Serum phosphorus and intact fibroblast growth factor 23 increased significantly during treatment.

CONCLUSIONS

Treatment of metabolic acidosis with sodium bicarbonate significantly improved vascular endothelial function in patients with stages 3b and 4 CKD.

Phosphate binders for preventing and treating chronic kidney disease-mineral and bone disorder (CKD-MBD)

BACKGROUND

Phosphate binders are used to reduce positive phosphate balance and to lower serum phosphate levels for people with chronic kidney disease (CKD) with the aim to prevent progression of chronic kidney disease-mineral and bone disorder (CKD-MBD). This is an update of a review first published in 2011.

OBJECTIVES

The aim of this review was to assess the benefits and harms of phosphate binders for people with CKD with particular reference to relevant biochemical end-points, musculoskeletal and cardiovascular morbidity, hospitalisation, and death.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 12 July 2018 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) or quasi-RCTs of adults with CKD of any GFR category comparing a phosphate binder to another phosphate binder, placebo or usual care to lower serum phosphate. Outcomes included all-cause and cardiovascular death, myocardial infarction, stroke, adverse events, vascular calcification and bone fracture, and surrogates for such outcomes including serum phosphate, parathyroid hormone (PTH), and FGF23.

DATA COLLECTION AND ANALYSIS

Two authors independently selected studies for inclusion and extracted study data. We applied the Cochrane 'Risk of Bias' tool and used the GRADE process to assess evidence certainty. We estimated treatment effects using random-effects meta-analysis. Results were expressed as risk ratios (RR) for dichotomous outcomes together with 95% confidence intervals (CI) or mean differences (MD) or standardised MD (SMD) for continuous outcomes.

MAIN RESULTS

We included 104 studies involving 13,744 adults. Sixty-nine new studies were added to this 2018 update.Most placebo or usual care controlled studies were among participants with CKD G2 to G5 not requiring dialysis (15/25 studies involving 1467 participants) while most head to head studies involved participants with CKD G5D treated with dialysis (74/81 studies involving 10,364 participants). Overall, seven studies compared sevelamer with placebo or usual care (667 participants), seven compared lanthanum to placebo or usual care (515 participants), three compared iron to placebo or usual care (422 participants), and four compared calcium to placebo or usual care (278 participants). Thirty studies compared sevelamer to calcium (5424 participants), and fourteen studies compared lanthanum to calcium (1690 participants). No study compared iron-based binders to calcium. The remaining studies evaluated comparisons between sevelamer (hydrochloride or carbonate), sevelamer plus calcium, lanthanum, iron (ferric citrate, sucroferric oxyhydroxide, stabilised polynuclear iron(III)-oxyhydroxide), calcium (acetate, ketoglutarate, carbonate), bixalomer, colestilan, magnesium (carbonate), magnesium plus calcium, aluminium hydroxide, sucralfate, the inhibitor of phosphate absorption nicotinamide, placebo, or usual care without binder. In 82 studies, treatment was evaluated among adults with CKD G5D treated with haemodialysis or peritoneal dialysis, while in 22 studies, treatment was evaluated among participants with CKD G2 to G5. The duration of study follow-up ranged from 8 weeks to 36 months (median 3.7 months). The sample size ranged from 8 to 2103 participants (median 69). The mean age ranged between 42.6 and 68.9 years.Random sequence generation and allocation concealment were low risk in 25 and 15 studies, respectively. Twenty-seven studies reported low risk methods for blinding of participants, investigators, and outcome assessors. Thirty-one studies were at low risk of attrition bias and 69 studies were at low risk of selective reporting bias.In CKD G2 to G5, compared with placebo or usual care, sevelamer, lanthanum, iron and calcium-based phosphate binders had uncertain or inestimable effects on death (all causes), cardiovascular death, myocardial infarction, stroke, fracture, or coronary artery calcification. Sevelamer may lead to constipation (RR 6.92, CI 2.24 to 21.4; low certainty) and lanthanum (RR 2.98, CI 1.21 to 7.30, moderate certainty) and iron-based binders (RR 2.66, CI 1.15 to 6.12, moderate certainty) probably increased constipation compared with placebo or usual care. Lanthanum may result in vomiting (RR 3.72, CI 1.36 to 10.18, low certainty). Iron-based binders probably result in diarrhoea (RR 2.81, CI 1.18 to 6.68, high certainty), while the risks of other adverse events for all binders were uncertain.In CKD G5D sevelamer may lead to lower death (all causes) (RR 0.53, CI 0.30 to 0.91, low certainty) and induce less hypercalcaemia (RR 0.30, CI 0.20 to 0.43, low certainty) when compared with calcium-based binders, and has uncertain or inestimable effects on cardiovascular death, myocardial infarction, stroke, fracture, or coronary artery calcification. The finding of lower death with sevelamer compared with calcium was present when the analysis was restricted to studies at low risk of bias (RR 0.50, CI 0.32 to 0.77). In absolute terms, sevelamer may lower risk of death (all causes) from 210 per 1000 to 105 per 1000 over a follow-up of up to 36 months, compared to calcium-based binders. Compared with calcium-based binders, lanthanum had uncertain effects with respect to all-cause or cardiovascular death, myocardial infarction, stroke, fracture, or coronary artery calcification and probably had reduced risks of treatment-related hypercalcaemia (RR 0.16, CI 0.06 to 0.43, low certainty). There were no head-to-head studies of iron-based binders compared with calcium. The paucity of placebo-controlled studies in CKD G5D has led to uncertainty about the effects of phosphate binders on patient-important outcomes compared with placebo.It is uncertain whether the effects of binders on clinically-relevant outcomes were different for patients who were and were not treated with dialysis in subgroup analyses.

AUTHORS' CONCLUSIONS

In studies of adults with CKD G5D treated with dialysis, sevelamer may lower death (all causes) compared to calcium-based binders and incur less treatment-related hypercalcaemia, while we found no clinically important benefits of any phosphate binder on cardiovascular death, myocardial infarction, stroke, fracture or coronary artery calcification. The effects of binders on patient-important outcomes compared to placebo are uncertain. In patients with CKD G2 to G5, the effects of sevelamer, lanthanum, and iron-based phosphate binders on cardiovascular, vascular calcification, and bone outcomes compared to placebo or usual care, are also uncertain and they may incur constipation, while iron-based binders may lead to diarrhoea.

Does inflammation affect outcomes in dialysis patients?

Chronic, low-grade inflammation is a common comorbid condition in chronic kidney disease (CKD), and particularly in chronic dialysis patients. In this review, we consider the question of whether inflammation affects outcomes in dialysis patients. Levels of proinflammatory cytokines, as well as C-reactive protein, are elevated in chronic dialysis patients. Multiple factors likely contribute to chronic inflammatory activation in kidney disease patients including the uremic milieu, lifestyle and epigenetic influences, infectious and thrombotic events, the dialysis process, and dysbiosis. Increased inflammatory markers in both CKD and chronic dialysis patients are associated with adverse clinical outcomes including all-cause mortality, cardiovascular events, kidney disease progression, protein energy wasting and diminished motor function, cognitive impairment, as well as other adverse consequences including CKD-mineral and bone disorder, anemia, and insulin resistance. Strategies that have been shown to reduce chronic systemic inflammation in CKD and chronic dialysis patients include both pharmacological and nonpharmacological interventions. However, despite evidence that systemic inflammatory markers can be lowered in kidney disease patients treated with various strategies, evidence that this improves clinical outcomes is largely unavailable and represents an important future research direction. Overall, there is strong observational evidence that inflammation is high in chronic dialysis patients and that this is independently associated with numerous adverse clinical outcomes. Targeting inflammation represents a potentially novel and attractive strategy if it can indeed improve adverse outcomes common in this population.

Current and potential therapeutic strategies for the management of vascular calcification in patients with chronic kidney disease including those on dialysis

Patients with CKD have accelerated vascular stiffening contributing significantly to excess cardiovascular morbidity and mortality. Much of the arterial stiffening is thought to involve vascular calcification (VC), but the pathogenesis of this phenomenon is complex, resulting from a disruption of the balance between promoters and inhibitors of calcification in a uremic milieu, along with derangements in calcium and phosphate metabolic pathways. Management of traditional cardiovascular risk factors to reduce VC may be influential but has not been shown to significantly improve mortality. Control of mineral metabolism may potentially reduce the burden of VC, although using conventional approaches of restricting dietary phosphate, administering phosphate binders, and use of active vitamin D and calcimimetics, remains controversial because recommended biochemical targets are hard to achieve and clinical relevance hard to define. Increasing time on dialysis is perhaps another therapy with potential effectiveness in this area. Despite current treatments, cardiovascular morbidity and mortality remain high in this group. Novel therapies for addressing VC include magnesium and vitamin K supplementation, which are currently being investigated in large randomized control trials. Other therapeutic targets include crystallization inhibitors, ligand trap for activin receptors and BMP-7. This review summarizes current treatment strategies and therapeutic targets for the future management of VC in patients with CKD.

Pharmacotherapy in chronic kidney disease hyperphosphatemia – effects on vascular calcification and bone health

Hyperphosphatemia (HP) in patients with chronic kidney disease (CKD) leads to complications such as renal osteodistrophy, cardiovascular calcification and hemodynamic abnormalities, all of them having a serious impact on the survival rate and quality of life. Also, HP is a key pathogenic factor in the development of secondary hyperparathyroidism (SHPT) in CKD. Having in regard the significance of controlling serum phosphorus levels (Pi), in this paper, the needs and obstacles to successful pharmacological management of HP in CKD are presented, with an overview of major classes of phosphate binders (PBs) and other drugs affecting Pi level, such as active vitamin D sterols and calcimimetics (CMs). In addition, their effects on progression of cardiovascular calcification and bone health are elaborated. In this regard, a PubMed search was carried out to capture all abstracts and articles relevant to the topic of CKD, HP and mineral metabolism, bone disorders and vascular/valvular calcification (VC), published from January 2007 to August 2017. The search was limited to English language, with the search terms including drug name AND hyperphosphatemia or cardiovascular calcification or bone disorder. Comparative studies, clinical studies/trials and meta-analyses related to different classes/representatives of PBs, vitamin D analogues and CMs were reviewed and research data related to their efficacy and safety compared. Keywords: chronic kidney disease, hyperphosphatemia, phosphate binders, active vitamin D sterols, calcimimetics, bone disorders, cardiovascular calcification

Comparative Efficacy and Safety of Phosphate Binders in Hyperphosphatemia Patients With Chronic Kidney Disease

BACKGROUND

In this study, we coordinated a network meta-analysis to establish the efficacy and safety of different agents used in the treatment of hyperphosphatemia patients with chronic kidney disease.

METHODS

PubMed, CNKI, and Embase were systematically searched to retrieve relevant studies. Outcomes were presented by mean differences, odds ratios, and corresponding 95% credible intervals for continuous outcomes and binary outcomes, respectively. Each therapy was ranked according to the value of surface under the cumulative ranking curve. Consistencies between direct and indirect comparisons were assessed with a node-splitting plot.

RESULTS

In terms of efficacy end points (including levels of serum phosphate, serum calcium, serum intact parathyroid hormone, and serum calcium × phosphorus product), all 7 kinds of agents outperformed or performed at least equally to placebo, with iron-based phosphate-binding agents being potentially the most effective. As for safety end points (including mortality, adverse events, and all-cause discontinuation), almost all agents were equivalent in term of mortality and all-cause discontinuation except in the comparison between iron-based phosphate-binding agents and placebo. Meanwhile, iron-based phosphate-binding agents colestilan and nicotinic acid performed poorly compared with placebo in terms of adverse events. Furthermore, iron-based phosphate-binding agents were potentially the safest agents followed sequentially by calcium-based phosphate-binding agents and placebo.

CONCLUSION

Iron-based phosphate-binding agents were the preferable agents when considering efficacy and safety simultaneously.

The efficacy and safety of sevelamer and lanthanum versus calcium-containing and iron-based binders in treating hyperphosphatemia in patients with chronic kidney disease: a systematic review and meta-analysis

Background

It remains unclear which phosphate binders should be preferred for hyperphosphatemia management in chronic kidney disease (CKD).

Methods

We performed a systematic review and meta-analysis of randomized trials comparing sevelamer or lanthanum with other phosphate binders in CKD.

Results

Fifty-one trials (8829 patients) were reviewed. Compared with calcium-based binders, all-cause mortality was nonsignificantly lower with sevelamer {risk ratio [RR] 0.62 [95% confidence interval (CI) 0.35-1.08]} and lanthanum [RR 0.73 (95% CI 0.18-3.00)], but risk of bias was concerning. Compared with calcium-based binders, sevelamer reduced the risk of hypercalcemia [RR 0.27 (95% CI 0.17-0.42)], as did lanthanum [RR 0.12 (95% CI 0.05-0.32)]. Sevelamer reduced hospitalizations [RR 0.50 (95% CI 0.31-0.81)], but not lanthanum [RR 0.80 (95% CI 0.34-1.93)]. The presence/absence of other clinically relevant outcomes was infrequently reported. Compared with calcium-based binders, sevelamer reduced serum calcium, low-density lipoprotein and coronary artery calcification, but increased intact parathyroid hormone. The clinical relevance of these changes is unknown since corresponding clinical outcomes were not reported. Lanthanum had less favorable impact on biochemical parameters. Sevelamer hydrochloride and sevelamer carbonate were similar in three studies. Sevelamer was similar to lanthanum (three studies) and iron-based binders (three studies).

Conclusion

Sevelamer was associated with a nonsignificant reduction in mortality and significantly lower hospitalization rates and hypercalcemia compared with calcium-based binders. However, differences in important outcomes, such as cardiac events, fractures, calciphylaxis, hyperchloremic acidosis and health-related quality of life remain understudied. Lanthanum and iron-based binders did not show superiority for any clinically relevant outcomes. Future studies that fail to measure clinically important outcomes (the reason why phosphate binders are prescribed in the first place) will be wasteful.

Cholecalciferol, Calcitriol, and Vascular Function in CKD: A Randomized, Double-Blind Trial

BACKGROUND AND OBJECTIVES

High circulating vitamin D levels are associated with lower cardiovascular mortality in CKD, possibly by modifying endothelial function. We examined the effect of calcitriol versus cholecalciferol supplementation on vascular endothelial function in patients with CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We performed a prospective, double-blind, randomized trial of 128 adult patients with eGFR=15-44 ml/min per 1.73 m2and serum 25-hydroxyvitamin D level <30 ng/ml at the University of Colorado. Participants were randomly assigned to oral cholecalciferol (2000 IU daily) or calcitriol (0.5 μg) daily for 6 months. The primary end point was change in brachial artery flow-mediated dilation. Secondary end points included changes in circulating markers of mineral metabolism and circulating and cellular markers of inflammation.

RESULTS

One hundred and fifteen patients completed the study. The mean (SD) age and eGFR of participants were 58±12 years old and 33.0±10.2 ml/min per 1.73 m2, respectively. There were no significant differences between groups at baseline. After 6 months, neither calcitriol nor cholecalciferol treatment resulted in a significant improvement in flow-mediated dilation (mean±SD percentage flow-mediated dilation; calcitriol: baseline 4.8±3.1%, end of study 5.1±3.6%; cholecalciferol: baseline 5.2±5.2%, end of study 4.7±3.6%); 25-hydroxyvitamin D levels increased significantly in the cholecalciferol group compared with the calcitriol group (cholecalciferol: 11.0±9.5 ng/ml; calcitriol: -0.8±4.8 ng/ml; P<0.001). Parathyroid hormone levels decreased significantly in the calcitriol group compared with the cholecalciferol group (median [interquartile range]; calcitriol: -22.1 [-48.7-3.5] pg/ml; cholecalciferol: -0.3 [-22.6-16.9] pg/ml; P=0.004).

CONCLUSIONS

Six months of therapy with calcitriol or cholecalciferol did not improve vascular endothelial function or improve inflammation in patients with CKD.

Inflammation and premature aging in advanced chronic kidney disease

Systemic inflammation in end-stage renal disease is an established risk factor for mortality and a catalyst for other complications, which are related to a premature aging phenotype, including muscle wasting, vascular calcification, and other forms of premature vascular disease, depression, osteoporosis, and frailty. Uremic inflammation is also mechanistically related to mechanisms involved in the aging process, such as telomere shortening, mitochondrial dysfunction, and altered nutrient sensing, which can have a direct effect on cellular and tissue function. In addition to uremia-specific causes, such as abnormalities in the phosphate-Klotho axis, there are remarkable similarities between the pathophysiology of uremic inflammation and so-called "inflammaging" in the general population. Potentially relevant, but still somewhat unexplored in this respect, are abnormal or misplaced protein structures, as well as abnormalities in tissue homeostasis, which evoke danger signals through damage-associated molecular patterns, as well as the senescence-associated secretory phenotype. Systemic inflammation, in combination with the loss of kidney function, can impair the resilience of the body to external and internal stressors by reduced functional and structural tissue reserves, and by impairing normal organ crosstalk, thus providing an explanation for the greatly increased risk of homeostatic breakdown in this population. In this review, the relationship between uremic inflammation and a premature aging phenotype, as well as potential causes and consequences, are discussed.

Secondary Hyperparthyroidism: Pathogenesis, Diagnosis, Preventive and Therapeutic Strategies

Uremic secondary hyperparathyroidism is a multifactorial and complex disease often present in advanced stages of chronic kidney disease. The accumulation of phosphate, the increased FGF23 levels, the reduction in active vitamin D production, and the tendency to hypocalcemia are persistent stimuli for the development and progression of parathyroid hyperplasia with increased secretion of PTH. Parathyroid proliferation may become nodular mainly in cases of advanced hyperparathyroidism. The alterations in the regulation of mineral metabolism, the development of bone disease and extraosseous calcifications are essential components of chronic kidney disease-mineral and bone disorder and have been associated with negative outcomes. The management of hyperparathyroidism includes the correction of vitamin D deficiency and control of serum phosphorus and PTH without inducing hypercalcemia. An update of the leading therapeutic tools available for the prevention and clinical management of secondary hyperparathyroidism, its diagnosis, and the main mechanisms and factors involved in the pathogenesis of the disease will be described in this review.

Effects of lanthanum carbonate and calcium carbonate on fibroblast growth factor 23 and hepcidin levels in chronic hemodialysis patients

BACKGROUND

Phosphate binders have an impact on fibroblast growth factor 23 (FGF23); however, the effect of phosphate binders on serum hepcidin has not been explored. We conducted a 24-week multicenter randomized controlled trial to investigate the effects of lanthanum carbonate or calcium carbonate monotherapy on serum phosphate, FGF23, and hepcidin levels in chronic hemodialysis patients.

METHODS

Forty-six patients were recruited, and daily dietary phosphorus was controlled between 600-800 mg. Serum calcium, phosphate, albumin, alkaline phosphatase (ALP), FGF23, intact parathyroid hormone (iPTH), hepcidin, high-sensitivity CRP (hsCRP), 25(OH)D, 1,25(OH)₂D, fetuin-A, and osteopontin were checked as scheduled.

RESULTS

Twenty-five patients completed the study. Mean serum FGF23 level was significantly decreased after a 24-week treatment with lanthanum (8677.5 ± 7490.0 vs. 4692.8 ± 5348.3 pg/mL, p = 0.013, n = 13), but not with calcium (n = 12). The reduction of serum hepcidin in lanthanum group was positively correlated with the decrement of serum phosphate (r = 0.631, p = 0.021) and serum hsCRP (r = 0.670, p = 0.012) levels, respectively. Serum ALP, iPTH, vitamin D, fetuin-A, and osteopontin revealed no significant inter- or intragroup differences.

CONCLUSIONS

In summary, a decrease in serum FGF23 levels and a trend of decline in hepcidin levels were observed only in lanthanum group.

Vascular Function and Uric Acid-Lowering in Stage 3 CKD

Hyperuricemia may contribute to endothelial dysfunction in CKD. We evaluated whether lowering serum uric acid levels with allopurinol improves endothelial dysfunction in 80 participants ≥18 years of age with stage 3 CKD and asymptomatic hyperuricemia (≥7 mg/dl in men and ≥6 mg/dl in women) randomized in a double-blinded manner to receive placebo or allopurinol for 12 weeks. Randomization was stratified according to presence or absence of diabetes mellitus. We measured vascular endothelial function by brachial artery flow-mediated dilation. No significant differences existed between groups at baseline; 61% of the participants had diabetes mellitus in both groups. The placebo and the allopurinol groups had baseline serum uric acid levels (SDs) of 8.7 (1.6) mg/dl and 8.3 (1.4) mg/dl, respectively, and baseline flow-mediated dilation values (SDs) of 6.0% (5.0%) and 4.8% (5.0%), respectively. Compared with placebo, allopurinol lowered serum uric acid significantly but did not improve endothelial function. In participants without diabetes mellitus, allopurinol associated with a trend toward improved flow-mediated dilation (+1.4% [3.9%] versus -0.7% [4.1%] with placebo), but this was not statistically significant (P=0.26). Furthermore, we did not detect significant differences between groups in BP or serum levels of markers of inflammation and oxidative stress. In conclusion, allopurinol effectively and safely lowered serum uric acid levels in adults with stage 3 CKD and asymptomatic hyperuricemia but did not improve endothelial function in this sample of patients.

Vascular calcification: When should we interfere in chronic kidney disease patients and how?

Chronic kidney disease (CKD) patients are endangered with the highest mortality rate compared to other chronic diseases. Cardiovascular events account for up to 60% of the fatalities. Cardiovascular calcifications affect most of the CKD patients. Most of this calcification is related to disturbed renal phosphate handling. Fibroblast growth factor 23 and klotho deficiency were incriminated in the pathogenesis of vascular calcification through different mechanisms including their effects on endothelium and arterial wall smooth muscle cells. In addition, deficient klotho gene expression, a constant feature of CKD, promotes vascular pathology and shares in progression of the CKD. The role of gut in the etio-pathogenesis of systemic inflammation and vascular calcification is a newly discovered mechanism. This review will cover the medical history, prevalence, pathogenesis, clinical relevance, different tools used to diagnose, the ideal timing to prevent or to withhold the progression of vascular calcification and the different medications and medical procedures that can help to prolong the survival of CKD patients.

Microvascular endothelial dysfunction is associated with albuminuria and CKD in older adults

Background

Impairment in glomerular endothelial function likely plays a major role in the development of albuminuria and CKD progression. Glomerular endothelial dysfunction may reflect systemic microvascular dysfunction, accounting in part for the greater cardiovascular risk in patients with albuminuria. Prior studies of vascular function in CKD have focused on conduit artery function or those with ESRD, and have not examined microvascular endothelial function with albuminuria.

Methods

We conducted a cross-sectional study among older hypertensive male veterans with stage 1–4 CKD, and hypertensive controls without CKD. Microvascular function was quantified by two distinct Laser-Doppler flowmetry (LDF) measures: peak responses to 1) post-occlusive reactive hyperemia (PORH) and 2) thermal hyperemia (TH), measured on forearm skin. Associations of each LDF measure with albuminuria, eGFR, and CKD status were estimated using correlation coefficients and multiple linear regression, accounting for potential confounders.

Results

Among 66 participants (mean age 69.2 years), 36 had CKD (mean eGFR 46.1 cc/min/1.73 m²; 30.6 % with overt albuminuria). LDF responses to PORH and TH were 43 and 39 % significantly lower in multivariate analyses among those with macroalbuminuria compared to normoalbuminuria, (β= − 0.42, p = 0.009 and β= −0.37, p = 0.01, respectively). Those with CKD had a 23.9 % lower response to PORH compared to controls (p = 0.02 after adjustment). In contrast, TH responses did not differ between those with and without CKD.

Conclusions

Microvascular endothelial function was strongly associated with greater albuminuria and CKD, independent of diabetes and blood pressure. These findings may explain in part the excess systemic cardiovascular risk associated with albuminuria and CKD.

Factors associated with serum fetuin-A concentrations after long-term use of different phosphate binders in hemodialysis patients

Background

Fetuin-A is known as a circulating inhibitor of vascular calcification. Factors associated with serum fetuin-A concentrations after long-term use of different phosphate binders in hemodialysis patients is still uncertain.

Methods

In the post-hoc study, we analyzed serum fetuin-A and biochemical factors (Ca, P, i-PTH, hsCRP, TG, LDL-C) in 50 hemodialysis patients, who completed a 48-week, open-Label, controlled randomized parallel-group study. 23 patients received sevelamer and 27 patients received calcium carbonate.

Results

After the 48-week treatment, the sevelamer group had less serum calcium increment, less iPTH decrement, more ALK-P increment, more hsCRP decrement and more LDL-C decrement. There was no significant difference in the serum fetuin-A decrement between two groups. Decreased serum fetuin-A levels were found after 48-week treatment in both groups: from 210.61 (104.73) to 153.85 (38.64) ug/dl, P = 0.003 in sevelamer group, from 203.95 (107.87) to 170.90 (58.02) ug/mL, P =0.002 in calcium group. The decrement in serum fetuin-A (Δfetuin-A) levels was associated with ΔCa (ρ = - 0.230, P = 0.040), ΔiPTH (ρ = 0.306, P = 0.031) and Δalbumin (ρ = 0.408, P = 0.003), not associated with sevelamer use, ΔP and ΔhsCRP.

Conclusion

After long-term sevelamer or calcium carbonate treatment, both groups of maintenance HD patients had lower serum fetuin-A levels. Serum levels of increased calcium, decreased iPTH and decreased albumin were associated with the serum fetuin-A decrement.

Therapeutics targeting persistent inflammation in chronic kidney disease

Systemic inflammation is a condition intrinsically linked to chronic kidney disease (CKD) and its other typical sequelae, such as acquired immune dysfunction, protein-energy wasting (PEW), and accelerated vascular aging that promote premature cardiovascular disease (CVD) and infections, the two leading causes of death in CKD patients. Inflammation is a major contributor to complications in CKD, and inflammatory markers, such as C-reactive protein and pro- and anti-inflammatory cytokines, correlate with underlying causes and consequences of the inflamed uremic phenotype, such as oxidative stress, endothelial dysfunction, CVD, PEW, and infections, and are sensitive and independent predictors of outcome in CKD. Therefore, inflammation appears to be a logical target for potential preventive and therapeutic interventions in patients with CKD. Putative anti-inflammatory therapy strategies aiming at preventing complications and improving outcomes in CKD span over several areas: (1) dealing with the source of inflammation (such as cardiovascular, gastrointestinal or periodontal disease and depression); (2) providing nonspecific immune modulatory effects by promoting healthy dietary habits and other lifestyle changes; (3) promoting increased use of recognized pharmacologic interventions that have pleiotropic effects; and, (4) introducing novel targeted anticytokine interventions. This review provides a brief update on inflammatory biomarkers and possible therapeutic approaches targeting inflammation and the uremic inflammatory milieu in patients with CKD.

C-reactive Protein: Repeated Measurements will Improve Dialysis Patient Care

Systemic inflammation is a common feature in the uremic phenotype and associates with poor outcomes. The awareness regarding the importance of inflammation assessment in chronic kidney disease (CKD) patients has risen in recent years, and despite the development of novel biomarkers, C-reactive protein (CRP) is still the most measured inflammatory parameter. Notwithstanding, the possible weak points of CRP determination, this biomarker has demonstrated being useful both for guidance in clinical practice and for risk estimation. In addition, regular determination of CRP among dialysis patients has been associated with better outcomes in different dialysis facilities. Because persistent inflammation may be a silent reflection of various pathophysiologic alterations in CKD, it is crucial that inflammatory markers are regularly monitored and therapeutic attempts be made to target this inflammation.

Malnutrition in Dialysis Patients--The Need for Intervention Despite Uncertain Benefits

We are in the midst of an epidemic of overnutrition which has resulted in a widespread increase in obesity rates in modern societies. Yet for patients suffering from serious chronic illnesses such as end stage renal disease (ESRD), malnutrition (encompassing both inadequate quantity and quality of nutrient intake) represents a far more significant danger. Protein-energy wasting has been identified as one of the strongest risk factor for adverse outcomes in ESRD patients, and modeling studies have suggested that improving nutrition could result in substantial lowering of mortality rates and other benefits. To date there is ample evidence that various interventions can have a positive impact on the nutritional status of ESRD patients, yet we still lack randomized controlled clinical trials showing that the same interventions could indeed lead to better survival or other clinical benefits. This knowledge gap, which is all too common for clinical problems encountered in nephrology, should not act as a deterrent, but it should rather incentivize us to continue exploring novel interventions aimed at improving malnutrition in ESRD.

Use of sevelamer in chronic kidney disease: beyond phosphorus control

Sevelamer is a non-calcium phosphate binder used in advanced chronic kidney disease (CKD) and in dialysis for hyperphosphataemia control. Several experimental, observational studies and clinical trials have shown that sevelamer has pleiotropic effects, beyond hyperphosphataemia control, including actions on inflammation, oxidative stress, lipid profile and atherogenesis, vascular calcification, endothelial dysfunction and the reduction of several uremic toxins. This is the biological basis for its global effect on cardiovascular morbidity and mortality in patients with chronic kidney disease. This review focuses on these pleiotropic actions of sevelamer and their impact on cardiovascular health, with the experience published after more than ten years of clinical expertise.

Sevelamer carbonate: a review in hyperphosphataemia in adults with chronic kidney disease

Sevelamer carbonate (Renvela(®)), a buffered form of sevelamer hydrochloride (Renagel(®)), is an orally administered non-absorbed phosphate-binding anion exchange resin used in the treatment of hyperphosphataemia in chronic kidney disease (CKD). In the EU, sevelamer carbonate is approved in adult CKD patients who require dialysis and in those who do not require dialysis with serum phosphate levels ≥ 1.78 mmol/L, whereas in the USA sevelamer carbonate is approved in adult CKD patients who require dialysis. Sevelamer carbonate and sevelamer hydrochloride achieved similar reductions in serum phosphate levels in randomized comparative trials in patients with CKD receiving haemodialysis; sevelamer carbonate also reduced serum phosphate levels in noncomparative studies in CKD patients not requiring dialysis. The most common adverse events with sevelamer carbonate are gastrointestinal in nature. Sevelamer has pleiotropic effects, such as improving the serum lipid profile and attenuating endothelial and cardiovascular risk factors in CKD. All formulations of sevelamer have markedly higher acquisition costs than calcium-based phosphate binders. Cost-effectiveness analyses focusing specifically on sevelamer carbonate have not been conducted, and those based on clinical trial data with sevelamer hydrochloride have provided both favourable and unfavourable results compared with calcium-based phosphate binders, reflecting heterogeneity between modelled analyses in terms of data sources, assumptions, comparators, geographical regions, type of costs included and other factors. Although well-designed studies evaluating the impact of phosphate binders on hard clinical endpoints appear to be warranted, sevelamer carbonate may be particularly useful for the treatment of patients at risk of metabolic acidosis (offering advantages over sevelamer hydrochloride in this regard) and for individuals requiring treatment with a phosphate binding agent that does not contain aluminium or calcium.

Maternal plasma fetuin-A concentration is lower in patients who subsequently developed preterm preeclampsia than in uncomplicated pregnancy: a longitudinal study

Objective: Fetuin-A is a negative acute phase protein reactant that acts as a mediator for lipotoxicity, leading to insulin resistance. Intravascular inflammation and insulin resistance have been implicated in the mechanisms of disease responsible for preeclampsia (PE). Maternal plasma concentrations of fetuin-A at the time of diagnosis of preterm PE are lower than in control patients with a normal pregnancy outcome. However, it is unknown if the changes in maternal plasma fetuin-A concentrations precede the clinical diagnosis of the disease. We conducted a longitudinal study to determine whether patients who subsequently developed PE had a different profile of maternal plasma concentrations of fetuin-A as a function of gestational age (GA) than those with uncomplicated pregnancies. Methods: A longitudinal case-control study was performed and included 200 singleton pregnancies in the following groups: (1) patients with uncomplicated pregnancies who delivered appropriate for gestational age (AGA) neonates (n = 160); and (2) patients who subsequently developed PE (n = 40). Longitudinal samples were collected at each prenatal visit and scheduled at 4-week intervals from the first or early second trimester until delivery. Plasma fetuin-A concentrations were determined by ELISA. Analysis was performed using mixed-effects models. Results: The profiles of maternal plasma concentrations of fetuin-A differ between PE and uncomplicated pregnancies. Forward analysis indicated that the rate of increase of plasma fetuin-A concentration in patients who subsequently developed PE was lower at the beginning of pregnancy (p = 0.001), yet increased faster mid-pregnancy (p = 0.0017) and reached the same concentration level as controls by 26 weeks. The rate of decrease was higher towards the end of pregnancy in patients with PE than in uncomplicated pregnancies (p = 0.002). The mean maternal plasma fetuin-A concentration was significantly lower in patients with preterm PE at the time of clinical diagnosis than in women with uncomplicated pregnancies (p < 0.05). In contrast, there were no significant differences in maternal plasma fetuin-A concentration in patients who developed PE at term. Conclusions: (1) The profile of maternal plasma concentrations of fetuin-A over time (GA) in patients who develop PE is different from that of normal pregnant women; (2) the rate of change of maternal plasma concentrations of fetuin-A is positive (increases over time) in the midtrimester of normal pregnancy, and negative (decreases over time) in patients who subsequently develop PE; (3) at the time of diagnosis, the maternal plasma fetuin-A concentration is lower in patients with preterm PE than in those with a normal pregnancy outcome; however, such differences were not demonstrable in patients with term PE.

Vascular toxicity of phosphate in chronic kidney disease: beyond vascular calcification

Chronic kidney disease (CKD) is characterized by high cardiovascular morbidity/mortality, which is linked in part to vascular calcification (VC) and endothelial dysfunction (ED). Hyperphosphatemia, a feature of CKD, is a well-known inducer of VC in preclinical models and is associated with poor outcomes in epidemiological studies. However, it remains to be seen whether lowering phosphate levels in CKD patients reduces VC and the morbidity/mortality rate. Furthermore, it is now clear from preclinical and clinical studies that phosphate is involved in ED. The present article reviews the direct and indirect mechanisms (eg, via fibroblast growth factor 23 and/or parathyroid hormone) by which hyperphosphatemia influence the onset of VC and ED in CKD.

Sevelamer revisited: pleiotropic effects on endothelial and cardiovascular risk factors in chronic kidney disease and end-stage renal disease

Endothelial dysfunction underlies multiple cardiovascular consequences of chronic kidney disease (CKD) and antecedent diabetes or hypertension. Endothelial insults in CKD or end-stage renal disease (ESRD) patients include uremic toxins, serum uric acid, hyperphosphatemia, reactive oxygen species, and advanced glycation endproducts (AGEs). Sevelamer carbonate, a calcium-free intestinally nonabsorbed polymer, is approved for hyperphosphatemic dialysis patients in the US and hyperphosphatemic stage 3-5 CKD patients in many other countries. Sevelamer has been observed investigationally to reduce absorption of AGEs, bacterial toxins, and bile acids, suggesting that it may reduce inflammatory, oxidative, and atherogenic stimuli in addition to its on-label action of lowering serum phosphate. Some studies also suggest that noncalcium binders may contribute less to vascular calcification than calcium-based binders. Exploratory sevelamer carbonate use in patients with stages 2-4 diabetic CKD significantly reduced HbA1c, AGEs, fibroblast growth factor (FGF)-23, and total and low-density lipoprotein (LDL) cholesterol versus calcium carbonate; inflammatory markers decreased and defenses against AGEs increased. Sevelamer has also been observed to reduce circulating FGF-23, potentially reducing risk of left ventricular hypertrophy. Sevelamer but not calcium-based binders in exploratory studies increases flow-mediated vasodilation, a marker of improved endothelial function, in patients with CKD. In contrast, lanthanum carbonate and calcium carbonate effects on FMV did not differ in hemodialysis recipients. The recent independent-CKD randomized trial compared sevelamer versus calcium carbonate in predialysis CKD patients (investigational in the US, on-label in European participants); sevelamer reduced 36-month mortality and the composite endpoint of mortality or dialysis inception. Similarly, independent-HD in incident dialysis patients showed improved survival with 24 months of sevelamer versus calcium-based binders. This review discusses recent exploratory evidence for pleiotropic effects of sevelamer on endothelial function in CKD or ESRD. Endothelial effects of sevelamer may contribute mechanistically to the improved survival observed in some studies of CKD and ESRD patients.

[Pleiotropic effects of sevelamer: a model of intestinal tract chelating agent]

The number of patients with chronic kidney disease (CKD) with its associated complications has increased dramatically worldwide in recent years. Therefore, many experimental and clinical studies have examined over the last decade the mechanisms involved, in order to explain the sharp increase in cardiovascular mortality. Hyperphosphatemia is a major problem in these patients especially at advanced stages of CKD, and it is associated with cardiovascular and mineral complications in these patients. Sevelamer is a phosphate binder that allows a better control of hyperphosphatemia, like other phosphate binder agents, but it has additional pleiotropic effects such as correcting certain abnormalities of lipid metabolism and clearance of several uremic toxins. These effects of sevelamer, restricted to the intestinal lumen, underline the importance of intestinal pathway in CKD and open the way to new therapeutic strategies for the management of the CKD and its complications.

Comparative effectiveness of calcium acetate and sevelamer on clinical outcomes in elderly hemodialysis patients enrolled in Medicare part D

BACKGROUND

Phosphate binders are an important therapeutic option for managing hyperphosphatemia in hemodialysis patients. Whether sevelamer confers a survival advantage over calcium acetate is unclear.

STUDY DESIGN

Observational cohort study using US Renal Data System (USRDS) data linked to Medicare Part D prescription drug data.

SETTING & PARTICIPANTS

Medicare-enrolled elderly incident hemodialysis patients initiating calcium acetate or sevelamer therapy between July 1, 2006, and March 31, 2011.

PREDICTOR

Prescription for sevelamer (hydrochloride or carbonate) or calcium acetate.

OUTCOMES & MEASUREMENTS

All-cause and cardiovascular-related mortality, hospital admissions and hospital days assessed from Medicare Parts A, B, and D claims and other USRDS data.

RESULTS

The sevelamer and calcium-acetate groups included 16,916 and 18,335 patients, respectively. After multivariable adjustment, all-cause (21.9 vs 21.8 deaths/100 patient-years; adjusted HR, 0.97; 95% CI, 0.94-1.03) and cardiovascular (8.7 vs 8.6 deaths/100 patient-years; HR, 0.99; 95% CI, 0.93-1.04) mortality did not differ significantly between the sevelamer and calcium-acetate (referent) groups. Mortality results in propensity score-matched cohorts showed significantly lower risk of death in sevelamer- than in calcium-acetate-treated patients (HR, 0.94; 95% CI, 0.91-0.98). Mortality results from additional analyses including only patients with low-income subsidy status were consistent with results from analyses including patients with and without low-income subsidy status. There were no significant differences between the sevelamer and calcium-acetate groups for all-cause and cardiovascular-related first hospitalization, multiple hospitalizations, and hospital days.

LIMITATIONS

Results may not be applicable to younger patients; information about laboratory data and over-the-counter calcium-containing binders was lacking.

CONCLUSIONS

Relative to treatment with calcium acetate, treatment with sevelamer was associated with similar or slightly lower risk of death and similar risk of hospitalization in elderly incident hemodialysis patients.

Phosphate restriction significantly reduces mortality in uremic rats with established vascular calcification

The role of hyperphosphatemia in the pathogenesis of secondary hyperparathyroidism, cardiovascular disease, and progression of renal failure is widely known. Here we studied effects of dietary phosphate restriction on mortality and vascular calcification in uremic rats. Control and uremic rats were fed a high-phosphate diet and at 3 months a portion of rats of each group were killed. Serum phosphate and the calcium phosphate product increased in uremic rats, as did aortic calcium. Of the rats, 56% had positive aortic staining for calcium (von Kossa), RUNX2, and osteopontin. The remaining uremic rats were continued on diets containing high phosphate without and with sevelamer, or low phosphate, and after 3 more months they were killed. Serum phosphate was highest in uremic rats on high phosphate. Serum PTH and FGF-23 were markedly lower in rats on low phosphate. Mortality on high phosphate was 71.4%, with sevelamer reducing this to 37.5% and phosphate restriction to 5.9%. Positive aortic staining for von Kossa, RUNX2, and osteopontin was increased, but phosphate restriction inhibited this. Kidneys from low-phosphate and sevelamer-treated uremic rats had less interstitial fibrosis, glomerulosclerosis, and inflammation than those of uremic rats on high phosphate. Importantly, kidneys from rats on low phosphate showed improvement over kidneys from high-phosphate rats at 3 months. Left ventricles from rats on low phosphate had less perivascular fibrosis and smaller cardiomyocyte size compared to rats on high phosphate. Thus, intensive phosphate restriction significantly reduces mortality in uremic rats with severe vascular calcification.

Management of hyperphosphataemia in chronic kidney disease: summary of National Institute for Health and Clinical Excellence (NICE) guideline

Bone disease and ectopic calcification are the two main consequences of hyperphosphataemia of chronic kidney disease (CKD). Observational studies have demonstrated that hyperphosphataemia in CKD is associated with increased mortality. Furthermore, the use of phosphate binders in dialysis patients is associated with significantly lower mortality. The UK Renal Registry data show significant underachievement of phosphate targets in dialysis patients. It is believed to be due to wide variation in how management interventions are used. The National Institute for Health and Clinical Excellence (NICE) has developed a guideline on the management of hyperphosphataemia in CKD. This is based on the evidence currently available using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology. This review outlines the recommendations including research recommendations and discusses methodology, rationale and challenges faced in developing this guideline and the health economic model used to assess the cost-effectiveness of different phosphate binders.

Plasma p-cresol lowering effect of sevelamer in peritoneal dialysis patients: evidence from a Cross-Sectional Observational Study

p-Cresol is a by-product of the metabolism of aromatic aminoacid operated by resident intestinal bacteria. In patients with chronic kidney disease, the accumulation of p-cresol and of its metabolite p-cresyl-sulphate causes endothelial dysfunction and ultimately increases the cardiovascular risk of these patients. Therapeutic strategies to reduce plasma p-cresol levels are highly demanded but not available yet. Because it has been reported that the phosphate binder sevelamer sequesters p-cresol in vitro we hypothesized that it could do so also in peritoneal dialysis patients. To explore this hypothesis we measured total cresol plasma concentrations in 57 patients with end-stage renal disease on peritoneal dialysis, 29 receiving sevelamer for the treatment of hyperphosphatemia and 28 patients not assuming this drug. Among the patients not assuming sevelamer, 16 were treated with lanthanum whereas the remaining 12 received no drug because they were not hyperphosphatemic. Patients receiving sevelamer had plasma p-cresol and serum high sensitivity C-reactive protein concentrations significantly lower than those receiving lanthanum or no drug. Conversely, no difference was observed among the different groups either in residual glomerular filtration rate, total weekly dialysis dose, total clearance, urine volume, protein catabolic rate, serum albumin or serum phosphate levels. Multiple linear regression analysis showed that none of these variables predicted plasma p-cresol concentrations that, instead, negatively correlated with the use of sevelamer. These results suggest that sevelamer could be an effective strategy to lower p-cresol circulating levels in peritoneal dialysis patients in which it could also favorably affect cardiovascular risk because of its anti-inflammatory effect.

Use of phosphate-binding agents is associated with a lower risk of mortality

Hyperphosphatemia has been associated with higher mortality risk in CKD 5 patients receiving dialysis. Here, we determined the association between the use of single and combined phosphate-binding agents and survival in 6797 patients of the COSMOS study: a 3-year follow-up, multicenter, open-cohort, observational prospective study carried out in 227 dialysis centers from 20 European countries. Patient phosphate-binding agent prescriptions (time-varying) and the case-mix-adjusted facility percentage of phosphate-binding agent prescriptions (instrumental variable) were used as predictors of the relative all-cause and cardiovascular mortality using Cox proportional hazard regression models. Three different multivariate models that included up to 24 variables were used for adjustments. After multivariate analysis, patients prescribed phosphate-binding agents showed a 29 and 22% lower all-cause and cardiovascular mortality risk, respectively. The survival advantage of phosphate-binding agent prescription remained statistically significant after propensity score matching analysis. A decrease of 8% in the relative risk of mortality was found for every 10% increase in the case-mix-adjusted facility prescription of phosphate-binding agents. All single and combined therapies with phosphate-binding agents, except aluminum salts, showed a beneficial association with survival. The findings made in the present association study need to be confirmed by randomized controlled trials to prove the observed beneficial effect of phosphate-binding agents on mortality.

Patient education for phosphorus management in chronic kidney disease

OBJECTIVES

This review explores the challenges and solutions in educating patients with chronic kidney disease (CKD) to lower serum phosphorus while avoiding protein insufficiency and hypercalcemia.

METHODS

A literature search including terms "hyperphosphatemia," "patient education," "food fatigue," "hypercalcemia," and "phosphorus-protein ratio" was undertaken using PubMed.

RESULTS

Hyperphosphatemia is a strong predictor of mortality in advanced CKD and is remediated via diet, phosphorus binders, and dialysis. Dietary counseling should encourage the consumption of foods with the least amount of inorganic or absorbable phosphorus, low phosphorus-to-protein ratios, and adequate protein content, and discourage excessive calcium intake in high-risk patients. Emerging educational initiatives include food labeling using a "traffic light" scheme, motivational interviewing techniques, and the Phosphate Education Program - whereby patients no longer have to memorize the phosphorus content of each individual food component, but only a "phosphorus unit" value for a limited number of food groups. Phosphorus binders are associated with a clear survival advantage in CKD patients, overcome the limitations associated with dietary phosphorus restriction, and permit a more flexible approach to achieving normalization of phosphorus levels.

CONCLUSION

Patient education on phosphorus and calcium management can improve concordance and adherence and empower patients to collaborate actively for optimal control of mineral metabolism.