Sevelamer attenuates the progression of coronary and aortic calcification in hemodialysis patients

Chronic kidney disease mineral bone disorder in childhood and young adulthood: a 'growing' understanding

Chronic kidney disease (CKD) mineral and bone disorder (MBD) comprises a triad of biochemical abnormalities (of calcium, phosphate, parathyroid hormone and vitamin D), bone abnormalities (turnover, mineralization and growth) and extra-skeletal calcification. Mineral dysregulation leads to bone demineralization causing bone pain and an increased fracture risk compared to healthy peers. Vascular calcification, with hydroxyapatite deposition in the vessel wall, is a part of the CKD-MBD spectrum and, in turn, leads to vascular stiffness, left ventricular hypertrophy and a very high cardiovascular mortality risk. While the growing bone requires calcium, excess calcium can deposit in the vessels, such that the intake of calcium, calcium- containing medications and high calcium dialysate need to be carefully regulated. Normal physiological bone mineralization continues into the third decade of life, many years beyond the rapid growth in childhood and adolescence, implying that skeletal calcium requirements are much higher in younger people compared to the elderly. Much of the research into the link between bone (de)mineralization and vascular calcification in CKD has been performed in older adults and these data must not be extrapolated to children or younger adults. In this article, we explore the physiological changes in bone turnover and mineralization in children and young adults, the pathophysiology of mineral bone disease in CKD and a potential link between bone demineralization and vascular calcification.

Dermatological Manifestations in Patients With Chronic Kidney Disease: A Review

Chronic kidney disease (CKD) is a progressive disease and has multiple clinical manifestations; when CKD reaches the end stage, at least one cutaneous manifestation appears due to some increased toxin levels or a constant proinflammatory state. Nonspecific manifestations include pruritus, xerosis, pigmentation disorders, acquired ichthyosis, purpuric spots, and nail disorders. Some specific manifestations are bullous dermatoses, acquired perforating dermatoses (APD), eruptive xanthoma, access site infections, calcifying disorders, and nephrogenic systemic fibrosis (NSF). All these cutaneous changes negatively impact patients; early recognition and diagnosis of these dermatoses will make a difference in their quality of treatment. Exploring a patient's skin is fundamental to suspect some diseases and increased toxin levels; pruritus occurs when uremic toxins are raised, and nail disorders are associated with hypoalbuminemia. This review provides the clinician with information on the clinical manifestations that occur in CKD, including epidemiology, pathophysiology, clinical manifestations, diagnosis, histopathology, treatment, and life impact of the dermatoses in CKD.

Sevelamer Use and Mortality in People with Chronic Kidney Disease Stages 4 and 5 Not on Dialysis

Rationale and objective: Data suggest that non-calcium-based binders, and specifically sevelamer, may lead to lower rates of death when compared with calcium-based binders in end-stage renal disease (ESRD) patients. However, the association between sevelamer use and mortality for those with non-dialysis-dependent chronic kidney disease (NDD-CKD) patients has been uncertain. Study design: Our research is presented in a prospective cohort study. Setting and participants: A total of 966 participants with NDD-CKD stages 4-5 were enrolled in the PECERA study from 12 centers in Spain. Exposure: The participants were treated with sevelamer. Outcome: This study yielded all-cause and cardiovascular mortality outcomes. Analytical approach: We conducted an association analysis between mortality and sevelamer use with time-dependent Cox proportional hazards models. Results: After a median follow-up of 29 months (IQR: 13-36 months), death occurred in 181 participants (19%), with cardiovascular (n = 95, 53%) being the leading cause of death. In a multivariable model, the adjusted hazard ratios (HRs) for patients under sevelamer treatment were 0.44 (95% CI, 0.22 to 0.88) and 0.37 (95% CI, 0.18 to 0.75) for all-cause and cardiovascular mortality, respectively, compared with those of untreated patients. Limitations: Some limitations include potential confusion via indication bias; causal statements about these associations cannot be made due to the observational nature of this study. Conclusions: In this prospective NDD-CKD cohort study, the administration of sevelamer was independently associated with lower all-cause and cardiovascular mortality, suggesting that non-calcium-based phosphate binders might be the first-line therapy for phosphate lowering in this population. Further interventional studies clarifying the risks and benefits of phosphate binders in NDD-CKD are warranted.

Can we reverse arterial stiffness by intervening on CKD-MBD biomarkers?

The increased cardiovascular risk of chronic kidney disease may in part be the consequence of arterial stiffness, a typical feature of kidney failure. Deranged homeostasis of minerals and hormones involved (CKD-MBD), are also strongly associated with this increased risk. It is well established that CKD-MBD is a main driver of vascular calcification, which in turn worsens arterial stiffness. However, there are other contributors to arterial stiffness in CKD than calcification. An overlooked possibility is that CKD-MBD may have detrimental effects on this potentially better modifiable component of arterial stiffness. In this review, the individual contributions of short-term changes in calcium, phosphate, PTH, vitamin D, magnesium, and FGF23 to arterial stiffness, in most studies assessed as pulse wave velocity, is summarized. Indeed, there is evidence from both observational studies and interventional trials that higher calcium concentrations can worsen arterial stiffness. This, however, has not been shown for phosphate, and it seems unlikely that, apart from being a contributor to vascular calcification and having effects on the microcirculation, phosphate has no acute effect on large artery stiffness. Several interventional studies, both by infusing PTH and by abrupt lowering PTH by calcimimetics or surgery, virtually ruled out direct effects on large artery stiffness. A well-designed trial using both active and nutritional vitamin D as intervention found a beneficial effect for the latter. Unfortunately, the study had a baseline imbalance and other studies did not support its finding. Both magnesium and FGF23 do not seem do modify central arterial stiffness.

The Decrease in Serum Total Cholesterol and Low-Density Lipoprotein (LDL) Concentrations With the Initiation of Hemodialysis Despite a Concomitant Increase in Serum Albumin Concentrations

Background and objective Hemodialysis patients often have lower serum low-density lipoprotein (LDL) and total cholesterol concentrations compared to the general population. It is unclear if this is due to a persistent decline in the values due to kidney disease or if the hemodialysis itself is contributing to the lower values. It is often assumed that malnutrition and anorexia are the main causes of the low lipid concentration in hemodialysis patients. In this study, we aimed to determine the association between hemodialysis initiation and serum lipid and albumin concentrations. Methodology The medical records of all patients initiating hemodialysis over an 11-year period at a single center were retrospectively reviewed. The data of 145 patients who had all the required lab values available were ultimately included in the study. Serum lipid levels at the initiation of hemodialysis were compared to values obtained mostly 6-18 months later. In order to determine if poor nutritional status is the reason for the decline in serum lipid levels, the serum albumin concentration at the initiation of hemodialysis was compared to that obtained during follow-up labs. Results We observed that serum cholesterol concentration declined from an average of 147 mg/dL to 137 mg/dL, while LDL decreased from an average of 78 mg/dL to 68 mg/dL, and serum albumin concentration increased from 3.4 g/dL to 3.8 g/dL after an average follow-up period of 10.8 months. Conclusions Based on our findings, the decline in serum LDL and total cholesterol concentrations with the initiation of hemodialysis may not be attributed to poor nutritional intake.

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.

Kidney function, bone-mineral metabolism markers, and calcification of coronary arteries, aorta, and cardiac valves in older adults

BACKGROUND AND AIMS

The contribution of kidney dysfunction, especially at mild-to-moderate stages, and bone-mineral metabolism (BMM) markers to vascular calcification remains controversial or unclear. We comprehensively evaluated the association of kidney and BMM markers with coronary artery calcification (CAC) and extra-coronary calcification (ECC).

METHODS

In 1931 ARIC participants (age 73-95 years) without coronary heart disease at visit 7 (2018-19), we investigated the associations of estimated glomerular filtration rate (eGFR) (with creatinine, cystatin C, and both) and five serum BMM markers (calcium, fibroblast growth factor 23, magnesium, parathyroid hormone, and phosphorus) with high CAC and ECC (sex-race specific ≥75th vs. <75th percentile Agatston score) or any vs. zero CAC and ECC using multivariable logistic regression. For eGFR and BMM markers, we took their weighted cumulative averages from visit 1 (1987-89) to visit 5 (2011-13).

RESULTS

Lower eGFR, regardless of equations used, was not robustly associated with high CAC or ECC. Among BMM markers, only higher phosphorus levels, even within the normal range, showed robust associations with high CAC (only when modeled continuously) and ECC, independently of kidney function (e.g., odds ratio 1.94 [95%CI 1.38-2.73] for high aortic valve calcification, in the highest vs. lowest quartile). Results were generally consistent when analyzing any CAC or ECC, although cystatin C-based eGFR <60 mL/min/1.73 m2 became significantly associated with mitral valve calcification (odds ratio 1.69 [1.10-2.60]).

CONCLUSIONS

Among kidney and BMM measures tested, only serum phosphorus demonstrated robust associations with both CAC and ECC, supporting a key role of phosphorus in the pathophysiology of vascular calcification.

Circulating Extracellular Vesicle-Propagated microRNA Signature as a Vascular Calcification Factor in Chronic Kidney Disease

BACKGROUND

Chronic kidney disease (CKD) accelerates vascular calcification via phenotypic switching of vascular smooth muscle cells (VSMCs). We investigated the roles of circulating small extracellular vesicles (sEVs) between the kidneys and VSMCs and uncovered relevant sEV-propagated microRNAs (miRNAs) and their biological signaling pathways.

METHODS AND RESULTS

We established CKD models in rats and mice by adenine-induced tubulointerstitial fibrosis. Cultures of A10 embryonic rat VSMCs showed increased calcification and transcription of osterix (Sp7), osteocalcin (Bglap), and osteopontin (Spp1) when treated with rat CKD serum. sEVs, but not sEV-depleted serum, accelerated calcification in VSMCs. Intraperitoneal administration of a neutral sphingomyelinase and biogenesis/release inhibitor of sEVs, GW4869 (2.5 mg/kg per 2 days), inhibited thoracic aortic calcification in CKD mice under a high-phosphorus diet. GW4869 induced a nearly full recovery of calcification and transcription of osteogenic marker genes. In CKD, the miRNA transcriptome of sEVs revealed a depletion of 4 miRNAs, miR-16-5p, miR-17~92 cluster-originated miR-17-5p/miR-20a-5p, and miR-106b-5p. Their expression decreased in sEVs from CKD patients as kidney function deteriorated. Transfection of VSMCs with each miRNA-mimic mitigated calcification. In silico analyses revealed VEGFA (vascular endothelial growth factor A) as a convergent target of these miRNAs. We found a 16-fold increase in VEGFA transcription in the thoracic aorta of CKD mice under a high-phosphorus diet, which GW4869 reversed. Inhibition of VEGFA-VEGFR2 signaling with sorafenib, fruquintinib, sunitinib, or VEGFR2-targeted siRNA mitigated calcification in VSMCs. Orally administered fruquintinib (2.5 mg/kg per day) for 4 weeks suppressed the transcription of osteogenic marker genes in the mouse aorta. The area under the curve of miR-16-5p, miR-17-5p, 20a-5p, and miR-106b-5p for the prediction of abdominal aortic calcification was 0.7630, 0.7704, 0.7407, and 0.7704, respectively.

CONCLUSIONS

The miRNA transcriptomic signature of circulating sEVs uncovered their pathologic role, devoid of the calcification-protective miRNAs that target VEGFA signaling in CKD-driven vascular calcification. These sEV-propagated miRNAs are potential biomarkers and therapeutic targets for vascular calcification.

Impact of Arterial Calcification of the Lower Limbs on Long-Term Clinical Outcomes in Patients on Hemodialysis

Lower limbs' arterial calcification is significantly associated with the clinical severity of lower extremity artery disease (LEAD) in patients undergoing hemodialysis (HD). However, the association between arterial calcification of the lower limbs and long-term clinical outcomes in patients on HD has not been elucidated. Calcification scores of the superficial femoral artery (SFACS) and below-knee arteries (BKACS) were quantitatively evaluated in 97 HD patients who were followed for 10 years. Clinical outcomes, including all-cause and cardiovascular mortality, cardiovascular events, and limb amputation were evaluated. Risk factors for clinical outcomes were evaluated using univariate and multivariate Cox proportional hazard analyses. Furthermore, SFACS and BKACS were divided into three groups (low, middle, and high), and their associations with clinical outcomes were evaluated using Kaplan-Meier analysis. SFACS, BKACS, C-reactive protein, serum albumin, age, diabetes, presence of ischemic heart disease, and critical limb-threatening ischemia were significantly associated with 3-year and 10-year clinical outcomes in the univariate analysis. Multivariate analysis showed that SFACS was an independent factor associated with 10-year cardiovascular events and limb amputations. Kaplan-Meier life table analysis showed that higher SFACS and BKACS levels were significantly associated with cardiovascular events and mortality. In conclusion, long-term clinical outcomes and the risk factors in patients undergoing HD were evaluated. Arterial calcification of the lower limbs was strongly associated with 10-year cardiovascular events and mortality in patients undergoing HD.

Inflammatory, Metabolic, and Coagulation Effects on Medial Arterial Calcification in Patients with Peripheral Arterial Disease

Calcium deposits in the vessel wall in the form of hydroxyapatite can accumulate in the intimal layer, as in atherosclerotic plaque, but also in the medial layer, as in medial arterial calcification (MAC) or medial Möenckeberg sclerosis. Once considered a passive, degenerative process, MAC has recently been shown to be an active process with a complex but tightly regulated pathophysiology. Atherosclerosis and MAC represent distinct clinical entities that correlate in different ways with conventional cardiovascular risk factors. As both entities coexist in the vast majority of patients, it is difficult to estimate the relative contribution of specific risk factors to their development. MAC is strongly associated with age, diabetes mellitus, and chronic kidney disease. Given the complexity of MAC pathophysiology, it is expected that a variety of different factors and signaling pathways may be involved in the development and progression of the disease. In this article, we focus on metabolic factors, primarily hyperphosphatemia and hyperglycemia, and a wide range of possible mechanisms by which they might contribute to the development and progression of MAC. In addition, we provide insight into possible mechanisms by which inflammatory and coagulation factors are involved in vascular calcification processes. A better understanding of the complexity of MAC and the mechanisms involved in its development is essential for the development of potential preventive and therapeutic strategies.

Relationship between serum parathyroid hormone levels and abdominal aortic calcification in patients starting hemodialysis who have never taken calcium tablets, calcitriol, or vitamin D analogs

Background

Vascular calcification (VC) and secondary hyperparathyroidism (SHPT) are important causes of the high incidence of cardiovascular events in chronic kidney disease (CKD) patients. The relationship between parathyroid hormone (PTH) and VC is very complex. The aim of this study was to determine the correlation between PTH levels and abdominal aortic calcification (AAC) in patients starting hemodialysis who had not received calcium tablets, calcium-containing phosphorus binders, calcitriol, or vitamin D analogs.

Methods

Seventy-one patients were included. Latero-lateral X-ray lumbar radiography, serum intact PTH (iPTH) levels, and predialysis biochemical parameters were obtained. The degree of AAC was evaluated according to the methods described previously by Kauppila et al.

Results

We found that there was a strong negative correlation between serum PTH and AAC (Spearman’s rho −0.76, p < 0.001). Receiver operating characteristic (ROC) curve analysis showed that low serum PTH level could predict the presence and extent of AAC (area under the curve values were 0.9013 [p < 0.0001] and 0.780 [p = 0.0041], respectively).

Conclusions

Our results indicate that serum PTH level is significantly negatively correlated with AAC within a certain concentration range in patients starting hemodialysis who had not received calcium tablets, calcium-containing phosphorus binders, calcitriol, or vitamin D analogs.

Impact of Transferrin Saturation and Anemia on Radial Artery Calcification in Patients with End-Stage Kidney Disease

Background: Arterial calcification is an important factor in determining the prognosis of patients with chronic kidney disease (CKD). Few studies on aortic calcification have involved radial artery calcification (RAC). This study aimed to analyze risk factors for RAC in patients with end-stage kidney disease (ESKD) and investigate the relationship between subsequent cardiovascular events (CVE) and vascular access trouble (VAT). Methods: This cohort study included 64 consecutive patients with ESKD who initiated hemodialysis and underwent a procedure for the creation of a primary radiocephalic arteriovenous fistula (RCAVF). Small arterial specimens were obtained from patients during RCAVF surgery. Tissue samples were stained with von Kossa, and arterial microcalcification was evaluated. We analyzed the association between preexisting arterial microcalcifications, clinical characteristics, CVE, and VAT. Results: In the univariate analysis, RAC patients demonstrated high systolic blood pressure (sBP), low hemoglobin (Hb), and low transferrin saturation (TSAT) (<0.05, <0.05, and <0.05, respectively). In the multivariate analysis, Hb (HR−0.516 (0.278−0.959), p < 0.05), TSAT (HR−0.0012 (0.00000248−0.597), p < 0.05), and sBP (HR−1.037 (1.001−1.073), p < 0.05) were independent risk factors for RAC. The cumulative incidence rate of CVE/VAT was not associated with RAC for one year. Conclusion: RAC was associated with sBP, TSAT, and anemia; however, no association with CVE/VAT was observed.

Effect of lanthanum carbonate and calcium carbonate on the progression of coronary artery calcification among hemodialysis patients with vascular calcification risk: a randomized controlled trial

BACKGROUND

Coronary artery calcification (CAC) is predictive of cardiovascular events. We assessed whether a non-calcium-based phosphate binder, lanthanum carbonate (LC), could delay CAC progression compared with a calcium-based phosphate binder, calcium carbonate (CC), in hemodialysis patients.

METHODS

This was a subsidiary of the LANDMARK study, which is a multicenter, open-label, randomized control study comparing LC and CC for cardiovascular events among Japanese hemodialysis patients with hyperphosphatemia who were at risk of vascular calcification. Participants were randomly assigned (1:1) to receive LC or CC. The changes in the total Agatston score of CAC 2 years from baseline were the primary outcome. Secondary outcomes included the changes in the total Agatston score at 1 year from baseline and the changes in serum phosphate, corrected calcium, and intact parathyroid hormone concentrations.

RESULTS

Of 239 patients, 123 comprised the full analysis set. The median daily drug dose (mg) was 750 [interquartile range (IQR), 750‒1500] in the LC group and 3000 (IQR, 3000‒3000) in the CC group; it remained constant throughout the study period. There was no significant difference in the change in total Agatston score from baseline to 2 years between the LC and CC groups [368 (95% confidence interval, 57-680) in the LC group vs. 611 (105-1118) in the CC group; difference, 243 (- 352-838)].

CONCLUSIONS

LC-based treatment for hyperphosphatemia did not delay CAC for 2 years compared with CC-based treatment in hemodialysis patients with at least one risk factor for vascular calcification.

Phosphate Frustration: Treatment Options to Complement Current Therapies

Hyperphosphatemia eventually develops in almost all patients with advanced chronic kidney disease and is associated with negative clinical outcomes. Thus, guidelines recommend targeting treatment to normal phosphate levels in patients with chronic kidney disease. Despite low phosphorus diets, clearance by dialysis, and phosphate binder use, many patients with chronic kidney disease on dialysis are unable to consistently achieve and maintain serum phosphate concentrations <5.5 mg/dL. A chart audit of patients on dialysis receiving phosphate binders showed that 74 to 86% were unable to consistently achieve serum phosphate ≤5.5 mg/dL over 6 months. Furthermore, although there is evidence that serum phosphate concentrations <4.5 mg/dL are associated with improved survival and cardiovascular outcomes, real-world phosphate control data suggest achieving and maintaining this goal for most patients would be extremely challenging, if not near impossible, using current therapies. As phosphate binders can only remove approximately 300 mg of the 2,500 mg or more daily dietary phosphate intake, therapeutic innovations are necessary to improve phosphate management. We present treatment options to complement current therapies including tenapanor, a novel sodium/hydrogen exchanger isoform 3 inhibitor that blocks the dominant paracellular phosphate absorption pathway and has been shown to reduce phosphate levels in several clinical trials.

Role of endothelial cells in vascular calcification

Vascular calcification (VC) is active and regulates extraosseous ossification progress, which is an independent predictor of cardiovascular disease (CVD) morbidity and mortality. Endothelial cells (ECs) line the innermost layer of blood vessels and directly respond to changes in flow shear stress and blood composition. Together with vascular smooth muscle cells, ECs maintain vascular homeostasis. Increased evidence shows that ECs have irreplaceable roles in VC due to their high plasticity. Endothelial progenitor cells, oxidative stress, inflammation, autocrine and paracrine functions, mechanotransduction, endothelial-to-mesenchymal transition (EndMT), and other factors prompt ECs to participate in VC. EndMT is a dedifferentiation process by which ECs lose their cell lineage and acquire other cell lineages; this progress coexists in both embryonic development and CVD. EndMT is regulated by several signaling molecules and transcription factors and ultimately mediates VC via osteogenic differentiation. The specific molecular mechanism of EndMT remains unclear. Can EndMT be reversed to treat VC? To address this and other questions, this study reviews the pathogenesis and research progress of VC, expounds the role of ECs in VC, and focuses on the regulatory factors underlying EndMT, with a view to providing new concepts for VC prevention and treatment.

A Comparison Between the Effects of Calcium Acetate and Sevelamer Carbonate on Progression of Aortic Vascular Calcification in Patients with Chronic Kidney Disease Stages 4 and 5

Background: Calcium-based and non-calcium-based phosphate binders are frequently used to treat hyperphosphatemia in patients with chronic kidney disease (CKD). Objectives: This study aimed to compare the effects of calcium acetate and sevelamer carbonate on the progression of aortic vascular calcification in patients with CKD stages 4 and 5. Methods: This was an open-label randomized prospective comparative study, in which the participants encompassed both male and female patients with ambulatory hyperphosphatemic CKD stages 4 and 5 aged above 18 years. One hundred fifty patients with CKD stages 4 and 5 were screened for Aortic vascular calcification using digital X-ray lumbar spine and multi-slice CT scan, of whom fifty patients with vascular calcification were selected and randomly assigned into two groups. The participants were then serially studied for the effects of phosphate binders on the progression of vascular calcification over one year. One group was prescribed calcium acetate, and the other group was prescribed sevelamer carbonate. Results: Fifty hyperphosphatemic CKD patients with a mean age of 57 years were randomly assigned into two groups. There was no statistically significant difference between the two groups; however, the patients assigned to the sevelamer group were older and higher aortic calcification index (ACI) (P = 0.035) and Kauppila scores (P = 0.04), and elevated serum calcium (P = 0.04), Ca X PO4 (P = 0.006), and vitamin D. In calcium acetate-treated patients, the mean ACI increased significantly during six months and one year; however, the increase was not significant in the sevelamer group. Serum cholesterol, serum triglycerides, serum iPTH level, and the inflammatory markers of atherosclerosis high sensitivity of C-reactive protein (hs-CRP), interleukin-6 (IL-6) (hs-CRP, IL-6) decreased significantly in the sevelamer group. Conclusions: The prevalence of vascular (abdominal aortic) calcification in pre-ESRD (CKD stage 4 and 5) patients was 75%. Abdominal aortic calcification increased significantly in calcium acetate-treated patients during six months and one year; however, the progression was not significant regarding sevelamer. Because of its pleiotropic properties, sevelamer is more effective and consistent in retarding the progression of vascular calcification than calcium acetate in patients with CKD stages 4 and 5.

Inhibit progression of coronary artery calcification with vitamin K in hemodialysis patients (the iPACK-HD study): a randomized, placebo-controlled multi-center, pilot trial

BACKGROUND

Vitamin K activates matrix Gla protein (MGP), a key inhibitor of vascular calcification. There is a high prevalence of sub-clinical vitamin K deficiency in patients with end-stage kidney disease.

METHODS

A parallel randomized placebo-controlled pilot trial was designed to determine whether 10 mg of phylloquinone thrice weekly versus placebo modifies coronary artery calcification progression over 12 months in patients requiring hemodialysis with a coronary artery calcium score (CAC) ≥30 Agatston Units (ClinicalTrials.gov identifier NCT01528800). The primary outcome was feasibility (recruitment rate, compliance with study medication, study completion and adherence overall to study protocol). CAC score was used to assess calcification at baseline and 12 months. Secondary objectives were to explore the impact of phylloquinone on vitamin K-related biomarkers (phylloquinone, dephospho-uncarboxylated MGP and the Gla-osteocalcin to Glu-osteocalcin ratio) and events of clinical interest.

RESULTS

A total of 86 patients with a CAC score ≥30 Agatston Units were randomized to either 10 mg of phylloquinone or a matching placebo three times per week. In all, 69 participants (80%) completed the trial. Recruitment rate (4.4 participants/month) and medication compliance (96%) met pre-defined feasibility criteria of ≥4.17 and ≥90%, respectively. Patients randomized to phylloquinone for 12 months had significantly reduced levels of dephospho-uncarboxylated MGP (86% reduction) and increased levels of phylloquinone and Gla-osteocalcin to Glu-osteocalcin ratio compared with placebo. There was no difference in the absolute or relative progression of coronary artery calcification between groups.

CONCLUSION

We demonstrated that phylloquinone treatment improves vitamin K status and that a fully powered randomized trial may be feasible.

Non calcium phosphate binders - Is there any evidence of benefit

PURPOSE OF REVIEW

Low-level evidence and opinion-based clinical practice guidelines highlight the substantial uncertainty in the practice patterns of hyperphosphatemia management in patients with chronic kidney disease (CKD). This manuscript reviews the evidence for the choice of phosphate binders and its impact on clinical outcomes.

RECENT FINDINGS

Phosphate binders are among the most common medications prescribed for patients on dialysis. Clinical practice guidelines recommend lowering phosphate levels toward normal range and restricting calcium-based binders in all CKD patients. There is substantial gap in the evidence underlying these recommendations with lack of any placebo-controlled, randomized trials showing survival benefits for any class of phosphate-binders. Despite the lack of evidence for specific phosphate target or if lowering phosphate improves survival, use of phosphate binders has remained central strategy in approach to hyperphosphatemia. Use of binders has added to the cost and contributed significant pill burden. Restriction of calcium-based binders to avoid positive calcium balance and consequent vascular calcification risk has a physiological rationale and weight of observational studies.

SUMMARY

There is currently no conclusive evidence that definitively guides the choice of any specific binders for management of hyperphosphatemia in patients with CKD. Use of noncalcium-based binders has a theoretical advantage in restricting total calcium intake to decrease the risk of vascular calcification but no proven benefits for mortality.

Postdialysis serum phosphate equilibrium in hemodialysis patients on a controlled diet and no binders

BACKGROUND

Studies evaluating the change in serum phosphate post hemodialysis (HD) demonstrate an initial decline during dialysis but a rebound post dialysis. However, previous studies were done on usual diet and phosphate binders, with limited number of blood draws, confounding conclusions. We determined serum phosphate reduction, rebound, and equilibrium over 48 h in HD patients consuming a controlled, low phosphorus diet without binders.

METHODS

Serum phosphate (mg/dL) was analyzed before and after a HD treatment and frequently during the ensuing 48 h intradialytic period in the clinical research unit. Thirteen subjects were enrolled and had been off phosphate binders for 10 days and consumed a standardized low phosphate (900 mg/day) diet for 3 weeks prior to the assessments. Linear regression was used to determine relationships between the pre-HD serum phosphate, decline post-HD (post-HD drop); and a 48 h area under curve (AUC) using the trapezoidal method as a measure of overall phosphate levels from the end of dialysis to 48 h post dialysis. Repeated Measures ANOVA with Dunnett's posthoc test was used to determine rebound.

RESULTS

Five of 13 subjects returned to >90% of their pre-HD serum phosphate within the first 24 h post-HD, and serum phosphate was 94 ± 0.11% (range 63%-113%) by 48 h after the completion of HD. The 48 h AUC of serum phosphate during the interdialytic period was correlated with both pre dialysis phosphorus (r = 0.85; p = 0.0002) and the pre-post drop in serum phosphate during dialysis (r = 0.69; p = 0.0085). In contrast, the net ultrafiltration was not related to the 48 h AUC of serum phosphorus (r = 0.20; p = 0.51).

CONCLUSIONS

In hemodialysis patients on standard low phosphorus diet and no phosphate binders, the interdialytic serum phosphorus level, assessed as AUC, is determined by the pre dialysis phosphorus and net-change in serum phosphorus during the dialysis treatment, but not the ultrafiltration volume [Correction added on 25 January, after first online publication: In the last sentence of the Abstract, the word "potassium" has been replaced with "phosphorus" to improve accuracy.].

Combining phosphate binder therapy with vitamin K2 inhibits vascular calcification in an experimental animal model of kidney failure

BACKGROUND

Hyperphosphataemia is strongly associated with cardiovascular disease and mortality. Recently, phosphate binders (PBs), which are used to bind intestinal phosphate, have been shown to bind vitamin K, thereby potentially aggravating vitamin K deficiency. This vitamin K binding by PBs may offset the beneficial effects of phosphate reduction in reducing vascular calcification (VC). Here we assessed whether combining PBs with vitamin K2 supplementation inhibits VC.

METHODS

We performed 3/4 nephrectomy in rats, after which warfarin was given for 3 weeks to induce vitamin K deficiency. Next, animals were fed a high phosphate diet in the presence of low or high vitamin K2 and were randomized to either control or one of four different PBs for 8 weeks. The primary outcome was the amount of thoracic and abdominal aorta VC measured by high-resolution micro-computed tomography (µCT). Vitamin K status was measured by plasma MK7 levels and immunohistochemically analysed in vasculature using uncarboxylated matrix Gla protein (ucMGP) specific antibodies.

RESULTS

The combination of a high vitamin K2 diet and PB treatment significantly reduced VC as measured by µCT for both the thoracic (P = 0.026) and abdominal aorta (P = 0.023), compared with MK7 or PB treatment alone. UcMGP stain was significantly more present in the low vitamin K2-treated groups in both the thoracic (P < 0.01) and abdominal aorta (P < 0.01) as compared with high vitamin K2-treated groups. Moreover, a high vitamin K diet and PBs led to reduced vascular oxidative stress.

CONCLUSION

In an animal model of kidney failure with vitamin K deficiency, neither PB therapy nor vitamin K2 supplementation alone prevented VC. However, the combination of high vitamin K2 with PB treatment significantly attenuated VC.

Interventions to Attenuate Vascular Calcification Progression in Chronic Kidney Disease: A Systematic Review of Clinical Trials

Background Vascular calcification is associated with cardiovascular morbidity and mortality in people with chronic kidney disease (CKD). Evidence-based interventions that may attenuate its progression in CKD remain uncertain.

Methods We conducted a systematic review of prospective clinical trials of interventions to attenuate vascular calcification in people with CKD, compare with placebo, another comparator, or standard of care. We included prospective clinical trials (randomized and nonrandomized) involving participants with stage 3-5D CKD or kidney transplant recipients; the outcome was vascular calcification measured using radiological methods. Quality of evidence was determined by the Cochrane risk of bias assessment tool and the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) method.

Results There were 77 trials (63 randomized) involving 6898 participants eligible for inclusion (median sample size, 50; median duration, 12 months); 58 involved participants on dialysis, 15 involved individuals with nondialysis CKD, and 4 involved kidney transplant recipients. Risk of bias was moderate over all. Trials involving magnesium and sodium thiosulfate consistently showed attenuation of vascular calcification. Trials involving intestinal phosphate binders, alterations in dialysate calcium concentration, vitamin K therapy, calcimimetics, and antiresorptive agents had conflicting or inconclusive outcomes. Trials involving vitamin D therapy and HMG-CoA reductase inhibitors did not demonstrate attenuation of vascular calcification. Mixed results were reported for single studies of exercise, vitamin E-coated or high-flux hemodialysis membranes, interdialytic sodium bicarbonate, SNF472, spironolactone, sotatercept, nicotinamide, and oral activated charcoal.

Conclusions Currently, there are insufficient or conflicting data regarding interventions evaluated in clinical trials for mitigation of vascular calcification in people with CKD. Therapy involving magnesium or sodium thiosulfate appears most promising, but evaluable studies were small and of short duration.

Past, Present, and Future of Phosphate Management

Cardiovascular (CV) disease (CVD) accounts for >50% of deaths with known causes in patients on dialysis. Elevated serum phosphorus levels are an important nontraditional risk factor for bone mineral disease and CVD in patients with chronic kidney disease (CKD). Given that phosphorus concentrations drive other disorders associated with increased CV risk (e.g., endothelial dysfunction, vascular calcification, fibroblast growth factor-23, parathyroid hormone), phosphate is a logical target to improve CV health. Phosphate binders are the only pharmacologic treatment approved for hyperphosphatemia. Although their safety has improved since inception, the mechanism of action leads to characteristics that make ingestion difficult and unpleasant; large pill size, objectionable taste, and multiple pills required for each meal and snack make phosphate binders a burden. Side effects, especially those affecting the gastrointestinal (GI) system, are common with binders, often leading to treatment discontinuation. The presence of “hidden” phosphates in processed foods and certain medications makes phosphate management even more challenging. Owing to these significant issues, most patients on dialysis are not consistently achieving and maintaining target phosphorus concentrations of <5.5 mg/dl, let alone more normal levels of <4.5 mg/dl, indicating novel approaches to improve phosphate management and CV health are needed. Several new nonbinder therapies that target intestinal phosphate absorption pathways have been developed. These include EOS789, which acts on the transcellular pathway, and tenapanor, which targets the dominant paracellular pathway. As observational evidence has established a strong association between phosphorus concentration and clinical outcomes, such as mortality, phosphate is an important target for improving the health of patients with CKD and end-stage kidney disease (ESKD).

Association between bone mineral metabolism and vascular calcification in end-stage renal disease

Background

Development of vascular calcification is accelerated in patients with end-stage renal disease. In addition to traditional risk factors of cardiovascular disease (CVD) abnormal bone and mineral metabolism together with many other factors contribute to the excess cardiovascular burden in patients on dialysis. Aortic calcification score and coronary calcification score are predictive of CVD and mortality. The aim of this study was to evaluate the possible relationship between arterial calcification and bone metabolism.

Methods

Thirty two patients on dialysis were included. All patients underwent a bone biopsy to assess bone histomorphometry and a ¹⁸F-NaF PET scan. Fluoride activity was measured in the lumbar spine (L1 – L4) and at the anterior iliac crest. Arterial calcification scores were assessed by computerized tomography for quantification of coronary artery calcification score and lateral lumbar radiography for aortic calcification score.

Results

This study group showed high prevalence of arterial calcification and 59% had verified CVD. Both CAC and AAC were significantly higher in patients with verified CVD. Only 22% had low turnover bone disease. There was a weak association between fluoride activity, which reflects bone turnover, measured in the lumbar spine, and CAC and between PTH and CAC. There was also a weak association between erosion surfaces and AAC. No significant association was found between calcification score and any other parameter measured.

Conclusions

The results in this study highlight the complexity, when evaluating the link between bone remodeling and vascular calcification in patients with multiple comorbidities and extensive atherosclerosis. Several studies suggest an impact of bone turnover on development of arterial calcification and there is some evidence of reduced progression of vascular calcification with improvement in bone status. The present study indicates an association between vascular calcification and bone turnover, even though many parameters of bone turnover failed to show significance. In the presence of multiple other factors contributing to the development of calcification, the impact of bone remodeling might be diminished.

Trial registration

The study is registered in ClinicalTrials.gov protocol registration and result system, ID is NCT02967042. Date of registration is 17/11/2016. 

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.

Different Effect of Lanthanum Carbonate and Sevelamer Hydrochloride on Calcium Balance in Patients with Moderate to Advanced Chronic Kidney Disease

Objective

Opposite to lanthanum carbonate (LC), sevelamer hydrochloride (SH) may increase intestinal calcium absorption. The study compared the effects of LC and SH on serum and urine phosphate and calcium, and on hormones regulating mineral-bone metabolism.

Patients and Methods

A prospective randomized crossover study included 34 patients with eGFR <60 mL/min. A single oral dose of LC (1,000 mg) or SH (2,400 mg) was administered in random order 15 minutes after a standardized meal fortified with 5 g calcium carbonate. Serum calcium, phosphate, and parathormone were measured before and 3, 6, 12, and 24 hours after each medication. Bone alkaline phosphatase (BAP), sclerostin, calcitriol, and FGF-23 were measured at baseline and after 12 and 24 hours. A 24-hour calcium and phosphate excretion was measured after each drug.

Results

Serum calcium increased 3 and 6 hours after SH then returned to baseline. After LC calcium was unchanged for up to 3 hours then transiently increased and eventually returned to baseline. The area under curve (AUC) of serum calcium for 12 hours after SH was larger than after LC (p=0.04). Serum phosphate decreased after each drug with a nadir 3 hours post-SH and 6 hours post-LC. AUC of serum phosphate was similar after both medications. PTH decreased transiently after both drugs. BAP did not change. FGF-23 was constant for the first 12 hours but later decreased after each drug.

Conclusion

A 2,400 mg SH and 1,000 mg LC are similarly effective in lowering serum phosphate in CKD, but LC induce in less intestinal calcium absorption after a meal. The trial was registered on February 23, 2018 in the clinicaltrial.gov database – NCT03451019.

Association of Matrix Metalloproteinase-2 (MMP-2) and MMP-9 Promoter Polymorphisms, Their Serum Levels, and Activities with Coronary Artery Calcification (CAC) in an Iranian Population

The serum levels and activity of matrix metalloproteinases (MMPs) are associated with the risk of coronary artery calcification (CAC). We sought to investigate the association between MMP-2 -1575G>A (rs243866) and MMP-9 -1562 C>T (rs3918242) SNPs with MMP-2 and MMP-9 serum levels and activity in individuals with CAC. One hundred and fifty-five cases with CAC and 155 healthy individuals as control group from West of Iran were included and frequency of genotypes and alleles of rs243866 and rs3918242 in MMP-2 and MMP-9 genes were determined using PCR-RFLP. We also investigated the serum levels of MMP-2 and MMP-9 and their activity using ELISA and gelatin zymography, respectively. Additionally, serum biochemical parameters including FBS (fasting blood sugar), urea, creatinine, cholesterol, triglyceride, HDL (high-density lipoprotein), LDL (low-density lipoprotein), calcium, and phosphorus as well as blood pressure (systolic blood pressure (SBP) and diastolic blood pressure (DBP)) were measured. Our results showed that both serum levels of MMP-2 and MMP-9 (P < 0.001) and their activity (P < 0.001) were higher in individuals with CAC when compared to the control group. Carrying A and T alleles in MMP-2 -1575G>A (rs243866) and MMP-9 -1562 C>T (rs3918242) SNPs, respectively, may predispose the individuals to CAC by acting as the risk factors. Serum levels and activity of MMP-2 and MMP-9 were found to be higher in CAC cases when compared to the healthy controls. Carriers of A allele in rs243866 SNP and T allele in rs3918242 SNP were shown to have higher MMP-2 and MMP-9 serum levels and activity that may result in increased ECM degradation and support the initiation and development of calcification.

Long-Term Effects of Sevelamer on Vascular Calcification, Arterial Stiffness, and Calcification Propensity in Patients Receiving Peritoneal Dialysis: The Randomized Pilot SERENE (Sevelamer on Vascular Calcification, Arterial Stiffness) Trial

Rationale & Objective

There is a concern regarding increased risk of vascular calcification with the use of calcium-based phosphorus binders. This study aimed to compare the effects of sevelamer used as a second-line, low-dose therapy with calcium-based phosphorus binders with those of sevelamer used as a first-line, high-dose therapy on coronary artery and heart valve calcification, aortic pulse wave velocity (PWV), and calcification propensity over 2 years in patients with hyperphosphatemia receiving peritoneal dialysis (PD).

Study Design

A 2-year-long prospective, multicenter, open-label, randomized pilot study.

Setting & Participants

Prevalent patients with hyperphosphatemia receiving PD from 2 university-affiliated hospitals in Hong Kong.

Interventions

The patients were randomized to receive sevelamer either as a first-line therapy at a high dose of 800 mg thrice daily (can titrate up to 1,200 mg thrice daily as required) or a second-line therapy at a low dose of 400 mg thrice daily with calcium carbonate to achieve a serum phosphorus target of ≤5.5 mg/dL.

Outcomes

The primary endpoints were changes in coronary artery calcium score and aortic PWV over 104 weeks. The secondary endpoints were changes in heart valve calcium scores, calcification propensity measure, and biochemical parameters of chronic kidney disease–mineral bone disease over 104 weeks.

Results

Among 60 prevalent patients receiving PD, with a mean age of 53 ± 10 years and with 57% men, changes in the coronary artery calcium score (median [interquartile range], 225 [79-525] vs 223 [56-1,212], respectively; P = 0.21), aortic PWV (mean ± standard error, 0.3 ± 0.1 vs 0.8 ± 0.2 m/s, respectively; P = 0.31), heart valve calcium score, maturation or transformation time, serum calcium levels, and phosphorus levels over 104 weeks were similar for the second-line, low-dose and first-line, high-dose sevelamer groups. Alkaline phosphatase and intact parathyroid hormone levels increased and low-density lipoprotein cholesterol decreased in both the groups, with no significant between-group differences.

Limitations

The sample size was small, and the dropout rates were relatively high.

Conclusions

Low-dose sevelamer used as a second-line therapy for hyperphosphatemia in combination with a calcium-based phosphorus binder had similar effects on vascular calcification, valvular calcification, and arterial stiffness compared with high-dose sevelamer used as a first-line therapy. This approach may be considered in resource-constrained countries to minimize calcium loading.

Funding

The study was supported by a competitive grant from SK Yee Medical Foundation. T50 assays and other biochemical assays were funded by a research grant from Sanofi Renal Corporation.

Trial Registration

NCT00745589.

Sevelamer Attenuates Bioprosthetic Heart Valve Calcification

Objective: Sevelamer hydrochloride is a phosphate binder used to treat hyperphosphatemia in chronic kidney disease (CKD) patients that can reduce valvular and vascular calcification. The aim of this study was to examine the effects of sevelamer treatment on calcification in bioprosthetic heart valves (BHVs).

Methods: Wister rats were randomly divided into three groups according to sevelamer intake and implantation (sham–sham operation; implant–implantation and normal diet, implant+S implantation, and sevelamer diet). Two kinds of BHVs—bovine pericardium treated with glutaraldehyde (GLUT) or non-GLUT techniques—were implanted in rat dorsal subcutis at 4 weeks. After implantation, sevelamer was administered to the implant+S group. The animals were executed at days 0 (immediately after implantation), 7, 14, 28, and 56. Calcium levels were determined by atomic absorption spectroscopy and von Kossa staining. Serum biochemistry analysis, Western blotting, real-time quantitative polymerase chain reaction, alkaline phosphatase activity measurement, histopathologic analysis, immunohistochemistry, and enzyme-linked immunosorbent assay were conducted to identify the anti-calcification mechanism of sevelamer.

Results: Non-GLUT crosslinking attenuates BHV calcification. Serum phosphate and calcium remained unreactive to sevelamer after a 14-day treatment. However, the mean calcium level in the implant+S group was significantly decreased after 56 days. In addition, the PTH level, inflammatory cell infiltration, system and local inflammation, and expression of Bmp2, Runx2, Alp, IL-1β, IL-6, and TNF-α were significantly reduced in the implant+S group.

Conclusion: Sevelamer treatment significantly attenuated the calcification of BHVs and had anti-inflammation effects that were independent from serum calcium and phosphate regulation. Thus, sevelamer treatment might be helpful to improve the longevity of BHVs.

Effects of sevelamer carbonate versus calcium acetate on vascular calcification, inflammation, and endothelial dysfunction in chronic kidney disease

Hyperphosphatemia is present in most patients with end‐stage renal disease (ESRD) and has been associated with increased cardiovascular mortality. Phosphate binders (calcium‐based and calcium free) are the mainstay pharmacologic treatment to lower phosphorus levels in patients with ESRD. We evaluated biochemical markers of vascular calcification, inflammation, and endothelial dysfunction in patients with chronic kidney disease (CKD) treated with sevelamer carbonate (SC) versus calcium acetate (CA). Fifty patients with CKD (stages 3 and 4) were enrolled and assigned to treatment with SC and CA for 12 weeks. At the end of the study the biomarkers of vascular calcification, inflammation, and endothelial dysfunction were analyzed. A significant increase in HDL‐cholesterol was observed with SC but not with CA in patients with CKD. Treatment with SC reduced serum phosphate, calcium phosphate, and FGF‐23 levels and there was no change with CA treatment. The inflammatory markers IL‐8, IFN‐γ, and TNFα decreased with response to both treatments. The levels of IL‐6 significantly increased with CA treatment and no change was observed in the SC treatment group. SC showed favorable effects on anti‐inflammatory and vascular calcification biomarkers compared to CA treatment in patients with CKD stages 3 and 4 with normal phosphorous values.

A feline-focused review of chronic kidney disease-mineral and bone disorders - Part 2: Pathophysiology of calcium disorder and extraosseous calcification

Derangements in mineral metabolism are one of the main entities in chronic kidney disease-mineral and bone disorder (CKD-MBD). This is the second of a two-part review of the physiology and pathophysiology of calcium homeostasis in feline CKD-MBD. While dysregulation in calcium homeostasis is known to contribute to the development of vascular calcification in CKD, evidence characterising the relationship between serum calcium concentration and nephrocalcinosis and nephrolithiasis is limited. Recently, fibroblast growth factor 23 (FGF23) and α-Klotho have gained increased research interest and been shown to be important biomarkers for the prediction of CKD progression in human patients. However, conflicting evidence exists on their role in calcium homeostasis and vascular and soft tissue calcification. This review details the pathophysiology of calcium disorders associated with CKD-MBD and its implications on vascular and soft tissue mineralisation in human and feline patients. Further prospective studies investigating the clinical consequences of calcium disturbances in cats with CKD are warranted and this may provide additional insight into the pathophysiology of feline CKD-MBD.

[Colonic Mass Secondary to Sevelamer-associated Rectal Ulcer]

The phosphorous balance is clinically important in increasing the long-term outcomes and preventing complications of end-stage renal disease. Sevelamer is a phosphate binder used widely to regulate hyperphosphatemia. On the other hand, gastrointestinal side effects increase with increasing sevelamer intake. A 29-year-old male with end-stage renal disease of IgA nephropathy on maintenance hemodialysis was admitted for diffuse alveolar bleeding and pneumonia. He presented with a low-grade fever and watery diarrhea tinged with blood. Initially, a Clostridioides difficile-associated diarrhea treatment was started with positive findings of Clostridioides difficile toxin and culture. Despite this, there was no improvement in the symptoms even with the appropriate antibiotic treatment. Computed tomography of the abdomen and pelvis revealed an occlusive mass in the rectum and secondary obstructive changes in the sigmoid colon. The initial suspicion was a malignancy or fungal infection. Sigmoidoscopy with a biopsy identified the mass as a lump of mucous material with the entire lumen covered with exudate. The subsequent histopathology examination revealed a colonic mucosal injury and characteristic "fish scale"-like sevelamer crystals in the exudate. The diagnosis of a sevelamer-induced rectal ulcer was made. We report this case of a sevelamer-associated rectal ulcer of the sigmoid.

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.

Circulatory microRNA expression profile for coronary artery calcification in chronic kidney disease patients

BACKGROUND & AIM

Coronary artery disease (CAD) is the primary cause of mortality in patients with end stage renal disease (ESRD). MicroRNA profiling is proven as a powerful tool in the diagnosis of any disease at the molecular level. Hence, the present study aimed to profile the microRNA expression for CAD especially coronary artery calcification in CKD patients.

MATERIALS AND METHODS

Two hundread patients with CKD stages 3 to 5 without dialysis and healthy controls were included in this study. All two hundred patients underwent 1024 multi sliceardiac computed tomography (CT) scan for calcium scoring. The calcium scoring more than 100 have been included in the study. We performed miRNA microarray analysis from serum samples of seven high calcium scored with CKD patients and one control patients.

RESULTS

Seven patients have observed circulating miRNAs has significantly upregulated and downregulated when compared with control patients. mir21, mir 67, mir 390, mir 56, mir 250, mir 65 and mir 13 were up regulated and mir235, mir256, mir226, mir207, mir255, mir193 were downregulated. There was no significant difference in left ventricle function.

CONCLUSION

13 microRNAs play a potential role in coronary artery calcification in CKD patients.

The cardiovascular-dialysis nexus: the transition to dialysis is a treacherous time for the heart

Chronic kidney disease (CKD) patients require dialysis to manage the progressive complications of uraemia. Yet, many physicians and patients do not recognize that dialysis initiation, although often necessary, subjects patients to substantial risk for cardiovascular (CV) death. While most recognize CV mortality risk approximately doubles with CKD the new data presented here show that this risk spikes to >20 times higher than the US population average at the initiation of chronic renal replacement therapy, and this elevated CV risk continues through the first 4 months of dialysis. Moreover, this peak reflects how dialysis itself changes the pathophysiology of CV disease and transforms its presentation, progression, and prognosis. This article reviews how dialysis initiation modifies the interpretation of circulating biomarkers, alters the accuracy of CV imaging, and worsens prognosis. We advocate a multidisciplinary approach and outline the issues practitioners should consider to optimize CV care for this unique and vulnerable population during a perilous passage.

Clinical Approach to Vascular Calcification in Patients With Non-dialysis Dependent Chronic Kidney Disease: Mineral-Bone Disorder-Related Aspects

Chronic kidney disease (CKD) is associated with a very high morbimortality, mainly from cardiovascular origin, and CKD is currently considered in the high- or very high risk- cardiovascular risk category. CKD-mineral and bone disorders (CKD-MBDs), including vascular and/or valvular calcifications, are also associated with these poor outcomes. Vascular calcification (VC) is very prevalent (both intimal and medial), even in non-dialysis dependent patients, with a greater severity and more rapid progression. Simple X-ray based-scores such as Adragão's (AS) are useful prognostic tools and AS (even AS based on hand-X-ray only) may be superior to the classic Kauppila's score when evaluating non-dialysis CKD patients. Thus, in this mini-review, we briefly review CKD-MBD-related aspects of VC and its complex pathophysiology including the vast array of contributors and inhibitors. Furthermore, although VC is a surrogate marker and is not yet considered a treatment target, we consider that the presence of VC may be relevant in guiding therapeutic interventions, unless all patients are treated with the mindset of reducing the incidence or progression of VC with the currently available armamentarium. Avoiding phosphate loading, restricting calcium-based phosphate binders and high doses of vitamin D, and avoiding normalizing (within the normal limits for the assay) parathyroid hormone levels seem logical approaches. The availability of new drugs and future studies, including patients in early stages of CKD, may lead to significant improvements not only in patient risk stratification but also in attenuating the accelerated progression of VC in CKD.

Effect of Treating Hyperphosphatemia With Lanthanum Carbonate vs Calcium Carbonate on Cardiovascular Events in Patients With Chronic Kidney Disease Undergoing Hemodialysis: The LANDMARK Randomized Clinical Trial

Importance

Among patients with hyperphosphatemia undergoing dialysis, it is unclear whether non-calcium-based phosphate binders are more effective than calcium-based binders for reducing cardiovascular events.

Objective

To determine whether lanthanum carbonate reduces cardiovascular events compared with calcium carbonate in patients with hyperphosphatemia at risk of vascular calcification undergoing hemodialysis.

Design, Setting, and Participants

Open-label, randomized, parallel-group clinical trial with blinded end point adjudication performed in 2374 patients with chronic kidney disease from 273 hemodialysis facilities in Japan. Eligible patients had hyperphosphatemia and 1 or more risk factors for vascular calcification (ie, ≥65 years, postmenopausal, diabetes). Enrollment occurred from November 2011 to July 2014; follow-up ended June 2018.

Interventions

Patients were randomized to receive either lanthanum carbonate (n = 1154) or calcium carbonate (n = 1155) and titrated to achieve serum phosphate levels of between 3.5 mg/dL and 6.0 mg/dL.

Main Outcomes and Measures

The primary outcome was a composite cardiovascular event (cardiovascular death, nonfatal myocardial infarction or stroke, unstable angina, transient ischemic attack, or hospitalization for heart failure or ventricular arrhythmia). Secondary outcomes included overall survival, secondary hyperparathyroidism-free survival, hip fracture-free survival, and adverse events.

Results

Among 2309 randomized patients (median age, 69 years; 40.5% women), 1851 (80.2%) completed the trial. After a median follow-up of 3.16 years, cardiovascular events occurred in 147 of 1063 patients in the lanthanum calcium group and 134 of 1072 patients in the calcium carbonate group (incidence rate, 4.80 vs 4.30 per 100 person-years; difference 0.50 per 100 person-years [95% CI, -0.57 to 1.56]; hazard ratio [HR], 1.11 [95%, CI, 0.88 to 1.41], P = .37). There were no significant differences in all-cause death (difference, 0.43 per 100 person-years [95% CI, -0.63 to 1.49]; HR, 1.10 [95% CI, 0.88 to 1.37]; P = .42) or hip fracture (difference, 0.10 per 100 person-years [95% CI, -0.26 to 0.47]; HR, 1.21 [95% CI, 0.62 to 2.35]; P = .58). The lanthanum carbonate group had an increased risk of cardiovascular death (difference, 0.61 per 100 person-years [95% CI, 0.02 to 1.21]; HR, 1.51 [95% CI, 1.01 to 2.27]; P = .045) and secondary hyperparathyroidism (difference, 1.34 [95% CI, 0.49 to 2.19]; HR, 1.62 [95% CI, 1.19 to 2.20]; P = .002). Adverse events occurred in 282 (25.7%) in the lanthanum carbonate group and 259 (23.4%) in the calcium carbonate groups.

Conclusions and Relevance

Among patients undergoing hemodialysis with hyperphosphatemia and at least 1 vascular calcification risk factor, treatment of hyperphosphatemia with lanthanum carbonate compared with calcium carbonate did not result in a significant difference in composite cardiovascular events. However, the event rate was low, and the findings may not apply to patients at higher risk.

Trial Registration

ClinicalTrials.gov Identifier: NCT01578200; UMIN Clinical Trial Registry Identifier: UMIN000006815.

Uremic Toxins: An Alarming Danger Concerning the Cardiovascular System

The kidneys and heart share functions with the common goal of maintaining homeostasis. When kidney injury occurs, many compounds, the so-called “uremic retention solutes” or “uremic toxins,” accumulate in the circulation targeting other tissues. The accumulation of uremic toxins such as p-cresyl sulfate, indoxyl sulfate and inorganic phosphate leads to a loss of a substantial number of body functions. Although the concept of uremic toxins is dated to the 1960s, the molecular mechanisms capable of leading to renal and cardiovascular injuries are not yet known. Besides, the greatest toxic effects appear to be induced by compounds that are difficult to remove by dialysis. Considering the close relationship between renal and cardiovascular functions, an understanding of the mechanisms involved in the production, clearance and overall impact of uremic toxins is extremely relevant for the understanding of pathologies of the cardiovascular system. Thus, the present study has as main focus to present an extensive review on the impact of uremic toxins in the cardiovascular system, bringing the state of the art on the subject as well as clinical implications related to patient’s therapy affected by chronic kidney disease, which represents high mortality of patients with cardiac comorbidities.

Effects of Myo-inositol Hexaphosphate (SNF472) on Bone Mineral Density in Patients Receiving Hemodialysis: An Analysis of the Randomized, Placebo-Controlled CaLIPSO Study

BACKGROUND AND OBJECTIVES

In the CaLIPSO study, intravenous administration of SNF472 (300 or 600 mg) during hemodialysis significantly attenuated progression of coronary artery and aortic valve calcification. SNF472 selectively inhibits formation of hydroxyapatite, the final step in cardiovascular calcification. Because bone mineral is predominantly hydroxyapatite, we assessed changes in bone mineral density in CaLIPSO.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Patients with coronary artery calcification at screening (Agatston score of 100-3500 U) were randomized 1:1:1 to receive placebo, 300 mg SNF472, or 600 mg SNF472 as an intravenous infusion during hemodialysis three times weekly for 52 weeks. Dual-energy x-ray absorptiometry (DXA) scans were obtained at baseline (screening) and end of treatment, and between-group changes from baseline were compared using analysis of covariance.

RESULTS

Among 274 randomized patients, 202 had evaluable DXA scans at baseline and postrandomization (the DXA-modified intention-to-treat population). Mean (95% confidence interval) changes in total-hip bone mineral density from baseline to week 52 were -1.5% (-2.7% to -0.3%), -1.5% (-2.7% to -0.4%), and -2.5% (-3.8% to -1.2%) in the placebo, 300 mg SNF472, and 600 mg SNF472 groups, respectively. Mean (95% confidence interval) changes in femoral-neck bone mineral density from baseline to week 52 were -0.3% (-1.6% to 1.0%), -1.0% (-2.3% to 0.2%), and -2.6% (-4.0% to -1.3%), respectively. Regression analyses showed no correlation between change in coronary artery calcium volume and change in bone mineral density at either location. Changes in serum alkaline phosphatase, calcium, magnesium, phosphate, and intact parathyroid hormone levels were similar across treatment groups. Clinical fracture events were reported for four of 90, three of 92, and six of 91 patients in the placebo, 300 mg SNF472, and 600 mg SNF472 groups, respectively.

CONCLUSIONS

Bone mineral density decreased modestly in all groups over 1 year. In the 600 mg SNF472 group, the reduction appeared more pronounced. Reported fractures were infrequent in all groups.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

Effect of SNF472 on Progression of Cardiovascular Calcification in End-Stage-Renal-Disease (ESRD) Patients on Hemodialysis (HD), NCT02966028.

Arterial Stiffness and Cardiovascular Risk in Hypertension

Arterial stiffness, a leading marker of risk in hypertension, can be measured at material or structural levels, with the latter combining effects of the geometry and composition of the wall, including intramural organization. Numerous studies have shown that structural stiffness predicts outcomes in models that adjust for conventional risk factors. Elastic arteries, nearer to the heart, are most sensitive to effects of blood pressure and age, major determinants of stiffness. Stiffness is usually considered as an index of vascular aging, wherein individuals excessively affected by risk factor exposure represent early vascular aging, whereas those resistant to risk factors represent supernormal vascular aging. Stiffness affects the function of the brain and kidneys by increasing pulsatile loads within their microvascular beds, and the heart by increasing left ventricular systolic load; excessive pressure pulsatility also decreases diastolic pressure, necessary for coronary perfusion. Stiffness promotes inward remodeling of small arteries, which increases resistance, blood pressure, and in turn, central artery stiffness, thus creating an insidious feedback loop. Chronic antihypertensive treatments can reduce stiffness beyond passive reductions due to decreased blood pressure. Preventive drugs, such as lipid-lowering drugs and antidiabetic drugs, have additional effects on stiffness, independent of pressure. Newer anti-inflammatory drugs also have blood pressure independent effects. Reduction of stiffness is expected to confer benefit beyond the lowering of pressure, although this hypothesis is not yet proven. We summarize different steps for making arterial stiffness measurement a keystone in hypertension management and cardiovascular prevention as a whole.

Valvular heart disease and calcification in CKD: more common than appreciated

Ischaemic heart disease, sudden cardiac death and arrhythmias, heart failure, stroke and peripheral arterial disease make up >50% of the causes of death in advanced chronic kidney disease (CKD). Calcification of the vascular tree and heart valves is partially related to these complications and has received growing attention in the literature. However, the main focus of research has been on the pathophysiology and consequences of vascular calcification, with less attention being paid to valvular calcification (VC) and its impact on the survival of CKD patients. Although VC has long been seen as an age-related degenerative disorder with minimal functional impact, several studies proved that it carries an increased risk of death and clinical consequences different from those of vascular calcification. In dialysis patients, the annual incidence of aortic valve calcification is nearly 3.3% and the reported prevalence of aortic and mitral VC varies between 25% and 59%. Moreover, calcification of both valves occurs 10-20 years earlier in CKD patients compared with the general population. Therefore, the purpose of this review is to summarize the current knowledge on the pathophysiology and relevance of VC in CKD patients, and to highlight specific clinical consequences and potential therapeutic implications.

Optimal Phosphate Control Related to Coronary Artery Calcification in Dialysis Patients

BACKGROUND

In patients on maintenance dialysis, cardiovascular mortality risk is remarkably high, which can be partly explained by severe coronary artery calcification (CAC). Hyperphosphatemia has been reported to be associated with the severity of CAC. However, the optimal phosphate range in patients on dialysis remains unknown. This study was planned to compare the effects on CAC progression of two types of noncalcium-based phosphate binders and of two different phosphate target ranges.

METHODS

We conducted a randomized, open-label, multicenter, interventional trial with a two by two factorial design. A total of 160 adults on dialysis were enrolled and randomized to the sucroferric oxyhydroxide or lanthanum carbonate group, with the aim of reducing serum phosphate to two target levels (3.5-4.5 mg/dl in the strict group and 5.0-6.0 mg/dl in the standard group). The primary end point was percentage change in CAC scores during the 12-month treatment.

RESULTS

The full analysis set included 115 patients. We observed no significant difference in percentage change in CAC scores between the lanthanum carbonate group and the sucroferric oxyhydroxide group. On the other hand, percentage change in CAC scores in the strict group (median of 8.52; interquartile range, -1.0-23.9) was significantly lower than that in the standard group (median of 21.8; interquartile range, 10.0-36.1; P=0.006). This effect was pronounced in older (aged 65-74 years) versus younger (aged 20-64 years) participants (P value for interaction =0.003). We observed a similar finding for the absolute change in CAC scores.

CONCLUSIONS

Further study with a larger sample size is needed, but strict phosphate control shows promise for delaying progression of CAC in patients undergoing maintenance hemodialysis.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

Evaluate the New Phosphate Iron-Based Binder Sucroferric Oxyhydroxide in Dialysis Patients with the Goal of Advancing the Practice of EBM (EPISODE), jRCTs051180048.

From organic and inorganic phosphates to valvular and vascular calcifications

Calcification of the arterial wall and valves is an important part of the pathophysiological process of peripheral and coronary atherosclerosis, aortic stenosis, ageing, diabetes, and chronic kidney disease. This review aims to better understand how extracellular phosphates and their ability to be retained as calcium phosphates on the extracellular matrix initiate the mineralization process of arteries and valves. In this context, the physiological process of bone mineralization remains a human model for pathological soft tissue mineralization. Soluble (ionized) calcium precipitation occurs on extracellular phosphates; either with inorganic or on exposed organic phosphates. Organic phosphates are classified as either structural (phospholipids, nucleic acids) or energetic (corresponding to phosphoryl transfer activities). Extracellular phosphates promote a phenotypic shift in vascular smooth muscle and valvular interstitial cells towards an osteoblast gene expression pattern, which provokes the active phase of mineralization. A line of defense systems protects arterial and valvular tissue calcifications. Given the major roles of phosphate in soft tissue calcification, phosphate mimetics, and/or prevention of phosphate dissipation represent novel potential therapeutic approaches for arterial and valvular calcification.

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.

Intestinal Chelators, Sorbants, and Gut-Derived Uremic Toxins

Chronic kidney disease (CKD) is a highly prevalent condition and is associated with a high comorbidity burden, polymedication, and a high mortality rate. A number of conventional and nonconventional risk factors for comorbidities and mortality in CKD have been identified. Among the nonconventional risk factors, uremic toxins are valuable therapeutic targets. The fact that some uremic toxins are gut-derived suggests that intestinal chelators might have a therapeutic effect. The phosphate binders used to prevent hyperphosphatemia in hemodialysis patients act by complexing inorganic phosphate in the gastrointestinal tract but might conceivably have a nonspecific action on gut-derived uremic toxins. Since phosphorous is a major nutrient for the survival and reproduction of bacteria, changes in its intestinal concentration may impact the gut microbiota’s activity and composition. Furthermore, AST-120 is an orally administered activated charcoal adsorbent that is widely used in Asian countries to specifically decrease uremic toxin levels. In this narrative review, we examine the latest data on the use of oral nonspecific and specific intestinal chelators to reduce levels of gut-derived uremic toxins.

Calcium-based phosphate binder use is associated with lower risk of osteoporosis in hemodialysis patients

Loss of bone mineral density (BMD) is a substantial risk of mortality in addition to fracture in hemodialysis patients. However, the factors affecting BMD are not fully determined. We conducted a single-center, cross-sectional study on 321 maintenance hemodialysis patients who underwent evaluation of femoral neck BMD using dual-energy X-ray absorptiometry from August 1, 2018, to July 31, 2019. We examined factors associated with osteoporosis defined by T-score of ≤  - 2.5, using logistic regression models. Median age of patients was 66 years, and 131 patients (41%) were diagnosed with osteoporosis. Older age, female, lower body mass index, diabetes mellitus, and higher Kt/V ratios were associated with higher osteoporosis risk. The only medication associated with lower osteoporosis risk was calcium-based phosphate binders (CBPBs) [odds ratio (OR), 0.41; 95% confidence interval (CI), 0.21-0.81]. In particular, CBPB reduced the osteoporosis risk within subgroups with dialysis vintage of ≥ 10 years, albumin level of < 3.5 mg/dL, active vitamin D analog use, and no proton pump inhibitor (PPI) use. In conclusion, CBPB use was associated with lower osteoporosis risk in hemodialysis patients. This effect might be partially attributable to calcium supplementation, given its higher impact in users of active vitamin D analogs or non-users of PPI, which modulate calcium absorption.