Effects of sevelamer on the progression of vascular calcification in patients on chronic haemodialysis

Recommended calcium intake in adults and children with chronic kidney disease-a European consensus statement

Mineral and bone disorders (MBD) are common in patients with chronic kidney disease (CKD), contributing to significant morbidity and mortality. For several decades, the first-line approach to controlling hyperparathyroidism in CKD was by exogenous calcium loading. Since the turn of the millennium, however, a growing awareness of vascular calcification risk has led to a paradigm shift in management and a move away from calcium-based phosphate binders. As a consequence, contemporary CKD patients may be at risk of a negative calcium balance, which, in turn, may compromise bone health, contributing to renal bone disease and increased fracture risk. A calcium intake below a certain threshold may be as problematic as a high intake, worsening the MBD syndrome of CKD, but is not addressed in current clinical practice guidelines. The CKD-MBD and European Renal Nutrition working groups of the European Renal Association (ERA), together with the CKD-MBD and Dialysis working groups of the European Society for Pediatric Nephrology (ESPN), developed key evidence points and clinical practice points on calcium management in children and adults with CKD across stages of disease. These were reviewed by a Delphi panel consisting of ERA and ESPN working groups members. The main clinical practice points include a suggested total calcium intake from diet and medications of 800-1000 mg/day and not exceeding 1500 mg/day to maintain a neutral calcium balance in adults with CKD. In children with CKD, total calcium intake should be kept within the age-appropriate normal range. These statements provide information and may assist in decision-making, but in the absence of high-level evidence must be carefully considered and adapted to individual patient needs.

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.

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.

Association between Serum Phosphate Levels and the Development of Aortic Stenosis in Patients Undergoing Hemodialysis

We aimed to investigate the factors associated with the development of aortic stenosis (AS) in patients undergoing hemodialysis (HD), and to elucidate the prognosis of HD patients with AS. Patients on HD that had also undergone echocardiography at Nagasaki Renal Center between July 2011 and June 2012 were included. Patients with AS at the time of inclusion were excluded. The diagnosis of AS was based on an annual routine or additional echocardiography. The patients were followed up until June 2021. The association between patient background and AS was also evaluated. Of the 302 patients (mean age, 67.4 ± 13.3 years; male, 58%; median dialysis history, 4.7 years), 60 developed AS and 10 underwent aortic valve replacement. A Cox proportional hazards model revealed that age (hazard ratio (HR), 1.07; 95% confidential interval (CI), 1.04–1.10; p < 0.001) and serum phosphate levels (HR, 1.40; 95%CI, 1.16–1.67, p < 0.001) were independent risk factors for developing AS. Incidentally, there was no significant mortality difference between patients with AS and those without (p = 0.53). Serum phosphate levels are a risk factor for developing AS and should be controlled. Annual echocardiography may contribute to the early detection of AS and improves the prognosis of patients undergoing HD.

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.

The predictive value of serum galectin 3 for abdominal aortic calcification in maintenance hemodialysis patients: A prospective cohort study

INTRODUCTION

Heterotopic vascular calcification is a common complication of maintenance hemodialysis (MHD) patients. Galectin 3 (Gal-3) has been reported to be associated with cardiovascular calcification. The current study aims to explore the potential predictive value of serum Gal-3 for severe abdominal aortic calcification (AAC) and AAC progression in MHD patients.

METHODS

A prospective cohort who underwent hemodialysis during July 2014 at the Blood Purification Center of Ruijin Hospital were followed up for 3 years. Two AAC assessments were performed: one at baseline and one after the 3-year follow-up period. Serum Gal-3 was detected with quantitative ELISA kits. SPSS 23.0 and MedCalc 11.4.2.0 were used to analyze the data.

FINDINGS

One hundred and fifty-two patients were recruited. Approximately 59.9% were male, the median age was 60 (50-67) years. Logistic regression analysis indicated that serum Gal-3 was an independent risk factor for both follow-up severe AAC and AAC progression. Receiver operating characteristic (ROC) curve analysis revealed significant prognostic value of serum Gal-3 for predicting severe AAC and AAC progression within 3 years.

DISCUSSION

We found serum Gal-3 is correlated to vascular calcification in ESRD patients. Gal-3 may be a potential biomarker of vascular calcification for MHD patients.

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.

Effects of different phosphate lowering strategies in patients with CKD on laboratory outcomes: A systematic review and NMA

BACKGROUND

Chronic kidney disease-mineral and bone disorder (CKD-MBD), a complication of chronic kidney disease, has been linked to reduced quality and length of life. High serum phosphate levels that result from CKD-MBD require phosphate-lowering agents, also known as phosphate binders. The objective of this systematic review is to compare the effects of available phosphate binders on laboratory outcomes in patients with CKD-MBD.

METHODS

Data sources included MEDLINE and EMBASE from January 1996 to April 2016, and the Cochrane Register of Controlled Trials up to April 2016. Teams of two reviewers, independently and in duplicate, screened titles and abstracts and potentially eligible full text reports to determine eligibility, and subsequently abstracted data and assessed risk of bias in eligible randomized controlled trials (RCTs). Eligible trials enrolled patients with CKD-MBD and randomized them to receive calcium-based phosphate binders (delivered as calcium acetate, calcium citrate or calcium carbonate), non-calcium-based phosphate binders (NCBPB) (sevelamer hydrochloride, sevelamer carbonate, lanthanum carbonate, sucroferric oxyhydroxide and ferric citrate), phosphorus restricted diet (diet), placebo or no treatment and reported effects on serum levels of phosphate, calcium and parathyroid hormone. We performed Bayesian network meta-analyses (NMA) to calculate the effect estimates (mean differences) and 95% credible intervals for serum levels of phosphate, calcium and parathyroid hormone. We calculated direct, indirect and network meta-analysis estimates using random-effects models. We applied the GRADE (Grading of Recommendations, Assessment, Development and Evaluation) approach to rate the quality of evidence for each pairwise comparison.

RESULTS

Our search yielded 1108 citations; 71 RCTs were retrieved for full review and 16 proved eligible. Including an additional 13 studies from a previous review, 29 studies that enrolled 8335 participants proved eligible; 26 trials provided data for quantitative synthesis. Sevelamer, lanthanum, calcium, iron, diet and combinations of active treatments (calcium or sevelamer or lanthanum and combination of calcium and sevelamer) resulted in significantly lower serum phosphate as compared to placebo (moderate to very low quality of evidence). We found no statistically significant differences between active treatment categories in lowering serum phosphate. Sevelamer, lanthanum and diet resulted in lower serum calcium compared to calcium (moderate quality evidence for lanthanum and diet; low quality evidence for Sevelamer). Iron, sevelamer and calcium yielded lower parathyroid hormone levels as compared to lanthanum. Meta-regression analyses did not yield a statistically significant association between treatment effect and trial duration.

DISCUSSION/CONCLUSIONS

We found few differences between treatments in impact on phosphate and differences in parathyroid hormone. Relative to calcium, sevelamer, lanthanum and diet showed significant reduction in serum calcium from baseline. Treatment recommendations should be based on impact on patient-important outcomes rather than on surrogate outcomes. Systematic review registration: PROSPERO CRD-42016032945.

Design and baseline characteristics of the LANDMARK study

Background

Calcium (Ca)-based phosphate (P) binders, compared to non-Ca-based P binders, contribute to vascular calcification, which is associated with cardiovascular events.

Methods

The LANDMARK study is a multicenter, randomized, open-label, parallel comparative study of lanthanum carbonate (LC) and calcium carbonate (CC) in hemodialysis patients. Stable hemodialysis patients with intact parathyroid hormone ≤240 pg/mL meeting ≥1 of the following criteria (age >65 years, postmenopause, diabetes mellitus) were randomized into the LC and CC groups. LC group patients initially received LC 750 mg/day or the previously used dose and were titrated up to a maximum 2250 mg/day to achieve serum P levels of 3.5–6.0 mg/dL. CC group patients received CC 3 g/day or the previously used dose and were titrated to achieve the same P range. If the target serum P level was not achieved, non-Ca-based P binders (other than LC) could also be added. The primary endpoint is survival time free of cardiovascular events, including cardiovascular death, non-fatal myocardial infarction or stroke, and unstable angina.

Results

Overall, 2309 patients were allocated to the LC (N = 1154) or CC group (N = 1155). At baseline, the mean age was 68.4 years, 40.4 % were women, 55.9 % had diabetes, 18.3 % had a history of ischemic heart disease, and 13.9 % had cerebrovascular disease. A total of 184 patients (8.4 %) had undergone coronary intervention procedures. Baseline characteristics were well balanced between groups.

Conclusions

The LANDMARK study will determine whether LC, a non-Ca-based P binder, reduces cardiovascular mortality and morbidity in chronic hemodialysis patients.

Comparative Effectiveness of Phosphate Binders in Patients with Chronic Kidney Disease: A Systematic Review and Network Meta-Analysis

BACKGROUND

Chronic kidney disease-mineral and bone disorder (CKD-MBD) has been linked to poor health outcomes, including diminished quality and length of life. This condition is characterized by high phosphate levels and requires phosphate-lowering agents-phosphate binders. The objective of this systematic review is to compare the effects of available phosphate binders on patient-important outcomes in patients with CKD-MBD.

METHODS

Data sources included MEDLINE and EMBASE Trials from 1996 to February 2016. We also searched the Cochrane Register of Controlled Trials up to April 2016. Teams of two reviewers, independently and in duplicate, screened titles and abstracts and potentially eligible full text reports to determine eligibility, and subsequently abstracted data and assessed risk of bias in eligible randomized controlled trials (RCTs). Eligible trials enrolled patients with CKD-MBD, randomized them to receive calcium (delivered as calcium acetate, calcium citrate or calcium carbonate), non-calcium-based phosphate binders (NCBPB) (sevelamer hydrochloride, sevelamer carbonate, lanthanum carbonate, sucroferric oxyhydroxide and ferric citrate), phosphorus restricted diet, placebo or no treatment, and reported effects on all-cause mortality, cardiovascular mortality or hospitalization at ≥4 weeks follow-up. We performed network meta-analyses (NMA) for all cause-mortality for individual agents (seven-node analysis) and conventional meta-analysis of calcium vs. NCBPBs for all-cause mortality, cardiovascular mortality and hospitalization. In the NMAs, we calculated the effect estimates for direct, indirect and network meta-analysis estimates; for both NMA and conventional meta-analysis, we pooled treatment effects as risk ratios (RR) and calculated 95% confidence intervals (CIs) using random effect models. We used the GRADE (Grading of Recommendations, Assessment, Development and Evaluation) approach to rate the quality of evidence for each paired comparison.

RESULTS

Our search yielded 1190 citations, of which 71 RCTs were retrieved for full review and 15 proved eligible. With 13 eligible studies from a prior review, we included 28 studies with 8335 participants; 25 trials provided data for our quantitative synthesis. Results suggest higher mortality with calcium than either sevelamer (NMA RR, 1.89 [95% CI, 1.02 to 3.50], moderate quality evidence) or NCBPBs (conventional meta-analysis RR, 1.76 [95% CI, 1.21 to 2.56, moderate quality evidence). Conventional meta-analysis suggested no difference in cardiovascular mortality between calcium and NCBPBs (RR, 2.54 [95% CI, 0.67 to 9.62 low quality evidence). Our results suggest higher hospitalization, although non-significant, with calcium than NCBPBs (RR, 1.293 [95% CI, 0.94 to 1.74, moderate quality evidence).

DISCUSSION/CONCLUSIONS

Use of calcium results in higher mortality than either sevelamer in particular and NCBPBs in general (moderate quality evidence). Our results raise questions about whether administration of calcium as an intervention for CKD- MBD remains ethical. Further research is needed to explore the effects of different types of phosphate binders, including novel agents such as iron, on quality and quantity of life.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD-42016032945.

A Study to Inform the Design of a National Multicentre Randomised Controlled Trial to Evaluate If Reducing Serum Phosphate to Normal Levels Improves Clinical Outcomes including Mortality, Cardiovascular Events, Bone Pain, or Fracture in Patients on Dialysis

Background. Retrospective, observational studies link high phosphate with mortality in dialysis patients. This generates research hypotheses but does not establish “cause-and-effect.” A large randomised controlled trial (RCT) of about 3000 patients randomised 50 : 50 to lower or higher phosphate ranges is required to answer the key question: does reducing phosphate levels improve clinical outcomes? Whether such a trial is technically possible is unknown; therefore, a study is necessary to inform the design and conduct of a future, definitive trial. Methodology. Dual centre prospective parallel group study: 100 dialysis patients randomized to lower (phosphate target 0.8 to 1.4 mmol/L) or higher range group (1.8 to 2.4 mmol/L). Non-calcium-containing phosphate binders and questionnaires will be used to achieve target phosphate. Primary endpoint: percentage successfully titrated to required range and percentage maintained in these groups over the maintenance period. Secondary endpoints: consent rate, drop-out rates, and cardiovascular events. Discussion. This study will inform design of a large definitive trial of the effect of phosphate on mortality and cardiovascular events in dialysis patients. If phosphate lowering improves outcomes, we would be reassured of the validity of this clinical practice. If, on the other hand, there is no improvement, a reassessment of resource allocation to therapies proven to improve outcomes will result. Trial Registration Number. This trial is registered with ISRCTN registration number ISRCTN24741445.

New Conclusions Regarding Comparison of Sevelamer and Calcium-Based Phosphate Binders in Coronary-Artery Calcification for Dialysis Patients: A Meta-Analysis of Randomized Controlled Trials

Background

Sevelamer hydrochloride is used widely, but its impact upon cardiovascular calcification, cardiovascular mortality, all-cause mortality and hospitalization is not known.

Outcomes

Primary outcome was cardiovascular calcification (coronary artery calcification scores (CACS) and aortic calcification scores (ACS)). Secondary outcomes were serum characteristics, hospitalization, cardiovascular mortality and all-cause mortality. Risk ratio (RR), mean differences and standard mean difference with 95% confidence intervals (CIs) were pooled using random- or fixed-effects models.

Results

We identified 31 studies (on 23 randomized controlled trials with 4395 participants). An analysis pooling showed a significant decrease in serum levels of phosphate with calcium-based phosphate binders (CBPBs) by 0.17 mg/dL [mean difference (MD), 95% CI, 0.03, 0.31] than sevelamer. A significant difference in the change of CACS by –102.66 [MD: 95% CI, –159.51, –45.80] and ACS by –1008.73 [MD, 95% CI, –1664.75, –352.72] between sevelamer and CBPBs was observed. Prevalence of hypercalcemia (serum levels of calcium >10.2–10.5 mg/dL and >11.0 mg/dL) was significantly smaller for sevelamer (RR = 0.44, 95% CI, 0.33, 0.58; RR = 0.24, 95% CI, 0.14, 0.40). No significant difference was found in hospitalization, all-cause mortality or cardiovascular mortality.

Conclusions

This meta-analysis suggests that sevelamer benefits dialysis patients in terms of CACS, ACS and hypercalcemia.

Hyperphosphatemia as an independent risk factor for coronary artery calcification progression in peritoneal dialysis patients

Background

Coronary artery calcification (CAC) is associated with cardiovascular mortality in end-stage renal disease (ESRD) patients. The present study aimed to identify modifiable risk factors for CAC progression in peritoneal dialysis (PD) patients.

Methods

Adult patients who received regular PD for more than 6 months and underwent a series of coronary artery calcification score (CaCS) measurements by multislice spiral computed tomography (MSCT) with an interval of ≥ 6 months were included in this observational cohort study. The demographic characteristics and clinical data, including laboratory data and adequacy of PD, were collected. Curve estimation was used to fit the straight line and obtain the slope. Binary logistic regression was performed to identify the independent risk factors for CAC progression in the PD patients, and multivariate linear regression was conducted to identify factors associated with hyperphosphatemia.

Results

A total of 207 adult patients on PD (116 men, 56.0 %) with a mean age of 59.8 ± 15.9 years were recruited to this study, and 157 of them (75.8 %) received three or more CaCS assessments. The patients were divided into a slow group (n = 137) and a rapid group (n = 70) according to the linear regression slope or the average speed of development. The follow-up time was 33.0 ± 18.8 months. Multivariate logistic regression revealed that age and serum phosphate level were independent risk factors for CAC progression after adjustments. Multivariate linear regression revealed that hyperphosphatemia was associated with elevations in the transferrin and serum albumin levels and normalized protein catabolic rate (nPCR) and reductions in the hemoglobin level, residual Ccr, and PD Ccr.

Conclusions

Hyperphosphatemia is an independent risk factor for CAC progression, and the serum phosphate level may be associated with protein intake and PD adequacy. These results provide important information for the clinical management of ESRD patients.

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.

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.

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.

Glycosaminoglycan overproduction in the aorta increases aortic calcification in murine chronic kidney disease

Background

Vascular calcification accompanying chronic kidney disease increases the mortality and morbidity associated with cardiovascular disorders, but no effective therapy is available. We hypothesized that glycosaminoglycans may contribute to osteoblastic differentiation of vascular smooth muscle cells during vascular calcification.

Methods and Results

We used exostosin‐like glycosyltranferase 2–deficient (EXTL2 knockout) mice expressing high levels of glycosaminoglycans in several organs including the aorta. We performed 5/6 subtotal nephrectomy and fed the mice a high‐phosphate diet to induce chronic kidney disease. Overexpression of glycosaminoglycans in the aorta enhanced aortic calcification in chronic kidney disease in EXTL2 knockout mice. Ex vivo and in vitro, matrix mineralization in aortic rings and vascular smooth muscle cells of EXTL2 knockout mice was augmented. Furthermore, removal of glycosaminoglycans in EXTL2 knockout and wild‐type mice‐derived vascular smooth muscle cells effectively suppressed calcium deposition in a high‐phosphate environment.

Conclusions

These results illustrate an important role for glycosaminoglycans in the development of vascular calcification. Manipulation of glycosaminoglycan expression may have beneficial effects on the progression of vascular calcification in chronic kidney disease patients.

The prognostic value of abdominal aortic calcification in peritoneal dialysis patients

OBJECTIVE

This study evaluated the prognostic value of the aortic calcification index (ACI), an estimate of abdominal aortic calcification by plain abdominal computed tomography (CT), in terms of left ventricular (LV) diastolic dysfunction, mortality, and nonfatal cardiovascular (CV) events in peritoneal dialysis (PD) patients.

METHOD

PD patients who received both abdominal CT and echocardiography were divided into a low-ACI group (n=46) and a high-ACI group (n=46).

RESULTS

During follow-up (median, 35.2 months; range, 3.6-111.3), 30 patients (32.6%) died and 10 patients (10.9%) developed nonfatal cardiovascular (CV) events. The 5-year event-free survival rates for mortality and nonfatal CV events were significantly lower in the high-ACI group compared with those in the low-ACI group (35.7% vs. 64.1%, P = 0.01). The ACI was positively correlated with left atrial diameter and ratio of peak early transmitral flow velocity to peak early diastolic mitral annular velocity (E/E' ratio; a marker of left ventricular diastolic function). Using multivariate analyses, the high-ACI group (vs. low-ACI group, HR 5.25, 95% CI 1.77-15.58, P = 0.003) and increased E/E' ratio (HR 1.16, 95% CI 1.03-1.31, P = 0.013) were independent predictors for mortality and CV events. The ACI provided a higher predictive value for adverse outcomes (AUC = 0.755, P = 0.002) than the E/E' ratio (AUC = 0.543, P = 0.61).

CONCLUSION

The ACI was significantly associated with left ventricular diastolic dysfunction and predicted all-cause mortality and nonfatal CV events in PD patients.

Management of hyperphosphataemia in chronic kidney disease-challenges and solutions

Hyperphosphataemia is a clinical consequence of the advanced stages of chronic kidney disease (CKD). Considerable evidence points to a role of hyperphosphataemia in the pathogenesis of CKD-associated cardiovascular (CV) complications, including vascular calcification, and with increased all-cause and CV mortality. These observations place management of hyperphosphataemia at the centre of CKD treatment. Although our increased understanding of the physiological role of FGF-23 may provide a long-term alternative biomarker of phosphate load and underlying disease progression, regular determination of serum phosphate is currently the most frequently used parameter to evaluate phosphate load in clinical practice. This review considers the challenges physicians and patients face in trying to control hyperphosphataemia. Amongst these are the limitations of dietary phosphate restriction, giving rise to the need for phosphate binder therapy to maintain serum phosphate control. Once the decision to use phosphate binders has been made, considerations include the relative efficacy, different potential side effects and pill burden associated with various phosphate binders. Although a number of phosphate binders are available, adherence poses a major obstacle to effective treatment. This emphasizes that further improvements to phosphate binder therapy can be made. Evaluation of novel agents and their potential role in the clinic should continue.

Abdominal aortic calcification is associated with diastolic dysfunction, mortality, and nonfatal cardiovascular events in maintenance hemodialysis patients

This study evaluated the significance of aortic calcification index (ACI), an estimate of abdominal aortic calcification by plain abdominal computed tomography (CT), in terms of left ventricular (LV) diastolic dysfunction, mortality, and nonfatal cardiovascular (CV) events in chronic hemodialysis patients. Hemodialysis patients who took both an abdominal CT and echocardiography were divided into a low-ACI group (n = 64) and a high-ACI group (n = 64). The high-ACI group was significantly older, had a longer dialysis vintage and higher comorbidity indices, and more patients had a previous history of CV disease than the low-ACI group. The ACI was negatively correlated with LV end-diastolic volume or LV stroke volume, and was positively correlated with the ratio of peak early transmitral flow velocity to peak early diastolic mitral annular velocity (E/E' ratio), a marker of LV diastolic function. The E/E' ratio was independently associated with the ACI. The event-free survival rates for mortality and nonfatal CV events were significantly lower in the high-ACI group compared with those in the low-ACI group, and the ACI was an independent predictor for all-cause deaths and nonfatal CV events. In conclusion, ACI is significantly associated with diastolic dysfunction and predicts all-cause mortality and nonfatal CV events in hemodialysis patients.

Potential influence of sevelamer hydrochloride on responsiveness to erythropoiesis-stimulating agents in haemodialysis patients

AIM

Vitamin D analogues, cinacalcet, and sevelamer play pivotal roles in the management of chronic kidney disease-mineral bone disorder, and are noted to have pleiotropic effects. We examined whether these agents might be associated with the responsiveness to erythropoiesis-stimulating agents (ESA).

METHODS

In this cross-sectional study including haemodialysis patients treated with ESA, we searched for clinical parameters associated with the ESA resistance index, which was calculated as the weekly ESA dose divided by the patient's haemoglobin value.

RESULTS

Among 45 patients (male: female = 28 : 17, age 68 ± 10 years, haemodialysis duration 84 ± 60 months), vitamin D analogue, cinacalcet, and sevelamer were used in 95.6%, 26.7%, and 84.4% of the patients, respectively. Univariate analysis showed significant association of the ESA resistance index with transferrin saturation rate (TSAT), vitamin D analogue dose, and sevelamer dose. In multivariate analysis, the sevelamer dose and TSAT were found to be independent determinants of the ESA resistance index.

CONCLUSION

Our preliminary data showed an independent association between sevelamer dose and the responsiveness to ESA in haemodialysis patients. Further studies are required to investigate the causal relationship between sevelamer and ESA responsiveness.

Clinicopathological variables predicting progression of azotemia in cats with chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) is common in geriatric cats, but often appears to be stable for long periods of time.

OBJECTIVES

To describe CKD progression and identify risk factors for progression in newly diagnosed azotemic cats.

ANIMALS

A total of 213 cats with CKD (plasma creatinine concentration > 2 mg/dL, urine specific gravity < 1.035) were followed up until progression occurred or for at least 1 year; 132, 73, and 8 cats were in International Renal Interest Society (IRIS) stages 2, 3, and 4, respectively.

METHODS

Progression was defined as a 25% increase in plasma creatinine concentration. Logistic regression was used to assess variables at diagnosis that were associated with progression within 1 year. Changes in IRIS stage during follow-up also were described. Cases that remained in stages 2 or 3, but did not have renal function assessed in the last 60 days of life, were excluded from analysis of the proportion reaching stage 4.

RESULTS

Of the cats, 47% (101) progressed within 1 year of diagnosis. High plasma phosphate concentration and high urine protein-to-creatinine ratio (UPC) predicted progression in all cats. Low PCV and high UPC independently predicted progression in stage 2 cats, whereas higher plasma phosphate concentration predicted progression in stage 3 cats; 19% (18/94) of cats diagnosed in stage 2; and 63% (34/54) of cats diagnosed in stage 3 reached stage 4 before they died.

CONCLUSIONS

Proteinuria, anemia, and hyperphosphatemia may reflect more progressive kidney disease. Alternatively, they may be markers for mechanisms of progression such as tubular protein overload, hypoxia, and nephrocalcinosis.

Effects of the Use of Non-Calcium Phosphate Binders in the Control and Outcome of Vascular Calcifications: A Review of Clinical Trials on CKD Patients

Vascular calcifications produce a high impact on morbidity and mortality rates in patients affected by chronic kidney disease and mineral bone disorder (CKD-MBD). Effects are manifested from the more advanced stages of CKD (stages 3-4), particularly in patients undergoing dialysis (CKD5D). In recent years, a large number of therapeutic options have been successfully used in the treatment of secondary hyperparathyroidism (SHPT), despite eliciting less marked effects on nonbone calcifications associated with CKD-MBD. In addition to the use of Vitamin D and analogues, more recently treatment with calcimimetic drugs has also been undertaken. The present paper aims to analyze comparative and efficacy studies undertaken to assess particularly the impact on morbidity and mortality rates of non-calcium phosphate binders. Moreover, the mechanism of action underlying the depositing of calcium and phosphate along blood vessel walls, irrespective of the specific contribution provided in reducing the typical phosphate levels observed in CKD largely at more advanced stages of the disease, will be investigated. The aim of this paper therefore is to evaluate which phosphate binders are characterised by the above action and the mechanisms through which these are manifested.

Evaluation of morbidity and mortality data related to cardiovascular calcification from calcium-containing phosphate binder use in patients undergoing hemodialysis

Cardiovascular disease is the leading cause of death among patients with stage 5 chronic kidney disease. Several mechanisms are thought to contribute to vascular calcification and subsequent cardiovascular disease in patients who require hemodialysis. One of these mechanisms is the use of calcium-containing phosphate binders to treat hyperphosphatemia. Although most phosphate binding occurs in the gastrointestinal tract, some calcium is inevitably absorbed and has the potential to perpetuate the calcium-phosphorus product and the development of vascular and soft tissue calcification. Some phosphate binders such as sevelamer hydrochloride do not contain calcium and therefore may not carry the same risks. We examined the cardiovascular calcification effect and morbidity and mortality data with calcium-containing phosphate binders compared with sevelamer hydrochloride when given to patients with stage 5 chronic kidney disease for the treatment of hyperphosphatemia. A literature search using the MEDLINE and PubMed databases identified relevant articles from 1989-2009; nine studies compared vascular calcification between a calcium-containing phosphate binder and sevelamer hydrochloride. Three mortality studies were also identified. Seven of the nine studies reported a statistically significant increase in vascular calcification in patients taking calcium-containing phosphate binders as measured by coronary artery calcification scores and aortic calcification scores. In two trials, lower mortality rates were observed in the patients receiving sevelamer hydrochloride compared with calcium-containing phosphate binders. No significant difference in the mortality rate was observed in the third trial. Based on the current literature, it appears that calcium-containing phosphate binders promote the progression of vascular calcification to a greater extent than does sevelamer hydrochloride. In addition, some evidence suggests that sevelamer hydrochloride may reduce all-cause mortality rates in patients undergoing hemodialysis, particularly those aged 65 years or older. Thus, although sevelamer hydrochloride appears to be the more appropriate choice of phosphate binder for patients undergoing hemodialysis in whom cardiovascular calcification is a concern, more clinical trials are needed to further guide practitioners on the selection of phosphate binders.

Update and critical appraisal of sevelamer in the management of chronic renal failure

Sevelamer (Renagel and Renvela), is an orally administered weakly basic anion exchange resin that binds dietary phosphate in the gastrointestinal tract, and is approved for use in the US, Europe and many other countries for the treatment of hyperphosphatemia in adult patients on hemodialysis or peritoneal dialysis. Clinical evidence shows that sevelamer is at least as effective as calcium-based oral phosphate binders in controlling serum phosphate, but with a lower incidence of hypercalcemia. Whilst sevelamer hydrochloride is associated with mild acidosis, sevelamer carbonate does not have this drawback. Use of sevelamer and avoidance of calcium-based binders may slow the progression of vascular calcification in hemodialysis patients, and it also reduces serum low-density lipoprotein-cholesterol levels. There was no between-group difference in all-cause mortality between sevelamer and calcium-based phosphate binder therapy in the primary efficacy analysis of the large (n >2100), 3-year DCOR trial. In the smaller (n = 109) nonblind RIND trial in patients new to hemodialysis, data suggest there may be an overall survival benefit with sevelamer versus calcium-based phosphate binder treatment but the evidence on the efficacy of sevelamer in reducing mortality and hospitalization is not strong. The balance of evidence, however, does not strongly support the use of sevelamer over the much less costly calcium-based binders except in patients at risk of hypercalcemic episodes. Further research into cardiovascular and all-cause mortality over a longer time period would be needed to settle this issue, and the relative survival benefits and cost effectiveness of all phosphate binder therapies remains to be fully determined. Despite the relative paucity of data available, sevelamer has established itself as the most widely used binder in the United States and the most widely used noncalcium-based binder worldwide. However, affordability is a major issue for most health economies and in the light of recent economic events is likely to become more prominent.

Serological cardiovascular and mortality risk predictors in dialysis patients receiving sevelamer: a prospective study

BACKGROUND

Cardiovascular morbidity and mortality are massively increased in patients with chronic kidney disease (CKD). Sevelamer hydrochloride has been shown to attenuate cardiovascular calcifications in CKD and end-stage renal disease (ESRD) patients. We assessed how sevelamer hydrochloride influences the evolution of serum fetuin-A and other serological factors predicting cardiovascular outcome and survival in haemodialysis patients.

METHODS

Fifty-seven prevalent haemodialysis patients were included in a three-phase prospective interventional trial (A-B-A design; 8 weeks per phase). Sevelamer was only administered in the middle phase of the study. Within the other two phases, >or=90% of the patients received calcium acetate for phosphate binding. Detailed time courses of serum biochemistries were analysed in order to obtain detailed insight into the influence of sevelamer upon CKD-mineral and bone disorder (MBD) parameters as well as serum fetuin-A, fibroblast growth factor 23 (FGF23) and uraemic toxin levels [uric acid, indoxyl sulphate, hippuric acid, indole acetic acid, p-cresol and 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid (CMPF)].

RESULTS

Forty-one patients finished the three prospective study phases (intention-to-treat analysis). After treatment with sevelamer, serum fetuin-A significantly increased (+21%), showing a delayed increase outlasting the third (non-sevelamer) study period. Total and low-density lipoprotein (LDL) cholesterol levels, as well as serum calcium, decreased significantly. The opposite occurred with albumin, C-reactive protein and intact parathyroid hormone (iPTH). FGF23, uric acid, indoxyl sulphate, hippuric acid, indole acetic acid, CMPF and serum phosphate did not change significantly during sevelamer treatment. In contrast, in parallel to sevelamer treatment, there was a significant rise in serum P-cresol.

CONCLUSIONS

In haemodialysis patients, treatment with sevelamer over 8 weeks was associated with a delayed yet long-lasting increase in serum fetuin-A levels. Increasing the serum level of fetuin-A, a negative acute-phase protein and systemic calcification inhibitor, might be one of the potential anti-calcification mechanisms of sevelamer. Since we failed to detect a decrease in systemic inflammation and uraemic toxins, the exact mechanisms by which sevelamer treatment affects serum fetuin-A remain to be determined.

Associations between vascular calcification, arterial stiffness and bone mineral density in chronic hemodialysis patients

AIM

The aim of our study was to examine the associations between vascular calcification, arterial stiffness and bone mineral density (BMD) in chronic hemodialysis (HD) patients.

METHODS

The study subjects were 83 (70 men and 13 women) HD patients. All patients had computed tomography (CT) to determine aortic calcification index (ACI), pulse wave velocity (PWV) using a volume-plethysmographic apparatus, and BMD estimated by digital image processing (DIP).

RESULTS

Patients, 84.3% male, 38.6% diabetic, had a mean age of 59.3 +/- 11.2 years. In univariate linear regression analysis, ACI correlated positively with age (r = 0.586, P < 0.0001), dialysis vintage (r = 0.47, P = 0.002), pulse pressure (r = 0.311, P = 0.004), C-reactive protein (CRP) (r = 0.226, P = 0.0397) and PWV (r = 0.422, P < 0.0001). There was no significant association between ACI and serum markers of mineral metabolism. There was also a positive association between PWV and systolic blood pressure (P = 0.0004) or pulse pressure (P < 0.0001), and a trend towards greater PWV with increasing age (r = 0.494). In multivariate regression analysis only increasing age, pulse pressure, serum levels of albumin and CRP were significantly associated with ACI and PWV. Mean BMD on DIP was 2.7 +/- 0.4 mmAL. ACI was inversely correlated with BMD (r = -0.234, P = 0.0331).

CONCLUSIONS

Vascular calcification is closely associated with arterial stiffness in HD patients. BMD is inversely correlated with ACI, suggesting that measurement of hand BMD by DIP is a useful tool for assessment of renal bone disease in these patients.

Progression of glomerular and tubular disease in pediatrics

Chronic kidney disease may be stimulated by many different etiologies, but its progression involves a common, yet complex, series of events that lead to the replacement of normal tissue with scar. These events include altered physiology within the kidney leading to abnormal hemodynamics, chronic hypoxia, inflammation, cellular dysfunction, and activation of fibrogenic biochemical pathways. The end result is the replacement of normal structures with extracellular matrix. Treatments presently are focused on delaying or preventing such progression, and are largely nonspecific. In pediatrics, such therapy is complicated further by pathophysiological issues that render children a unique population.

Clinical assessment of atherosclerotic parameters and cardiac function in chronic hemodialysis patients

BACKGROUND/AIM

Atherosclerosis is evaluated by carotid mean intima-media thickness (mean IMT), pulse wave velocity (PWV), and the aortic calcification index (ACI). We have attempted to examine if these atherosclerotic parameters are associated with each other and which parameters are closely related to cardiac function in chronic HD patients.

METHODS

The mean IMT, PWV and ACI were examined in 69 maintenance HD patients using carotid ultrasonography, a blood volume plethysmographic apparatus and abdominal CT, respectively. Echocardiographic studies were also performed for measuring left ventricular (LV) geometry. Serum total cholesterol, high density lipoprotein cholesterol, low density lipoprotein cholesterol, triglyceride, albumin, C-reactive protein (CRP), calcium and phosphate were measured.

RESULTS

The mean IMT correlated positively with ACI (r = 0.461, P < 0.0001) and tended to be correlated with PWV, but did not reach statistical significance. The PWV value correlated positively with ACI (r = 0.494, P <or= 0.0001). The mean IMT correlated positively with the LV mass index (r = 0.273, P = 0.0228), and fractional shortening (FS) correlated negatively with PWV value (r = -0.293, P = 0.0141) and ACI score (r = -0.289, P = 0.0158). Multivariate analyses indicated that the LV mass index was independently associated with mean IMT (P = 0.0231) as well as systolic blood pressure (P < 0.0001), pulse pressure (P < 0.0001) and hemoglobin (P = 0.016), and FS is independently associated with ACI (P = 0.0162) as well as PWV (P = 0.0144) and CRP (P = 0.0375).

CONCLUSION

Atherosclerosis and reduced LV function are associated with increased vascular calcification and arterial stiffness in chronic HD patients.

The effects of calcium-based versus non-calcium-based phosphate binders on mortality among patients with chronic kidney disease: a meta-analysis

BACKGROUND

The effects of calcium compared with non-calcium-based phosphate binders on mortality, cardiovascular events and vascular calcification in patients with chronic kidney disease (CKD) are unknown.

METHODS

To address this question, we conducted a systematic review. We electronically searched MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials and CINAHL. We identified 160 potential studies and included 8 randomized trials. Eligible studies, determined by consensus using predefined criteria, were reviewed, and data were extracted onto a standard from.

RESULTS

There was a trend towards a decrease in all-cause mortality among non-calcium-based versus calcium-based phosphate binders [relative risk (RR) 0.68; 95% CI 0.41-1.11] based upon eight randomized controlled trials and 2873 subjects. Two trials reported on cardiovascular events with a RR of 0.85 (95% CI 0.35-2.03) in patients receiving calcium-based versus non-calcium-based binders. Coronary artery calcification was reported in five trials involving 469 patients; the difference in the change in the calcium score from baseline to follow-up among subjects taking non-calcium-based binders versus calcium-based binders was -76.35 (95% CI -158.25-5.55).

CONCLUSION

Despite the trends observed, we did not find a statistically significant difference in cardiovascular mortality and coronary artery calcification in patients receiving calcium-based phosphate binders compared to non-calcium-based phosphate binders. However, the data are limited by the small number of studies and the confidence intervals do not exclude a potentially important beneficial effect. Therefore, further randomized trials are required.

Management of hyperphosphatemia in patients with end-stage renal disease: focus on lanthanum carbonate

Elevated serum phosphate levels as a consequence of chronic kidney disease (CKD) contribute to the increased cardiovascular risk observed in dialysis patients. Protein restriction and dialysis fail to adequately prevent hyperphosphatemia, and in general treatment with oral phosphate binding agents is necessary in patients with advanced CKD. Phosphate plays a pivotal role in the development of vascular calcification, one of the factors contributing to increased cardiovascular risk in CKD patients. Treatment of hyperphosphatemia with standard calcium-based phosphate binders and vitamin D compounds can induce hypercalcemic episodes, increase the Ca × PO₄ product and thus add to the risk of ectopic mineralization. In this review, recent clinical as well as experimental data on lanthanum carbonate, a novel, non-calcium, non-resin phosphate binding agent are summarized. Although lanthanum is a metal cation no aluminium-like toxicity is observed since the bioavailability of lanthanum is extremely low and its metabolism differs from that of aluminium. Clinical studies now document the absence of toxic effects of lanthanum for up to 6 years of follow-up. The effects of lanthanum on bone, vasculature and brain are discussed and put in perspective with lanthanum pharmacokinetics.

Plasma levels of fibroblast growth factor-23 and mineral metabolism in diabetic and non-diabetic patients on chronic hemodialysis

OBJECTIVE

Fibroblast growth factor (FGF) 23 is a circulating factor that regulates phosphate (P) metabolism. Since higher P levels are associated with vascular calcification, we examined the role of serum FGF-23 levels in P metabolism and vascular calcification in hemodialysis (HD) patients with and without diabetes mellitus (DM).

MATERIALS AND METHODS

Chronic HD patients with DM (n = 39) and without DM (n = 50) were enrolled. Serum samples were obtained before the start of dialysis sessions, and the FGF-23 levels were determined by enzyme-linked immunosorbent assay. Abdominal computed tomography (CT) scan was performed, and the aortic calcification index (ACI) was determined by one examiner, blinded to the patient characteristics. Measurements of bone mineral density (BMD) were performed at the time of ACI estimation.

RESULTS

Log plasma FGF-23 levels were higher in non-DM (3.74 +/- 0.71 pg/ml) than in DM (3.35 +/- 0.74 pg/ml) patients. The log FGF-23 correlated positively with serum creatinine (r = 0.424, P < 0.0001), albumin (r = 0.225, P = 0.0337), Ca (r = 0.392, P = 0.0001), P (r = 0.735, P < 0.0001), and Ca x P product (r = 0.780, P < 0.0001). There were negative correlations between log FGF-23 and age (r = -0.208, P = 0.0497), glucose (r = -0.231, P = 0.0294), and CRP (r = -0.222, P = 0.0359). Multiple regression analyses were performed to explore the correlations between plasma FGF-23 and other factors associated with vascular calcification in all HD patients. Independent variables were selected based on the results of univariate analyses. The significant factors associated with FGF-23 in HD patients were age, serum levels of creatinine, albumin, glucose, Ca, P, and Ca x P product. Plasma FGF levels did not correlate significantly with either ACI or BMD in these patients.

CONCLUSION

Our findings indicate that the plasma FGF-23 level is associated with calcium-phosphate metabolism disorders, but not with aortic calcification, in both non-DM and DM patients on chronic HD. In addition, plasma FGF-23 is associated with serum levels of creatinine and albumin. Therefore, the plasma FGF-23 level may provide a reliable marker for Ca and P imbalance and nutritional status in HD patients.