Calcium carbonate, but not sevelamer, is associated with better outcomes in hemodialysis patients: Results from the French ARNOS study

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

Analysis of the kinetics of the parathyroid hormone, and of associated patient outcomes, in a cohort of haemodialysis patients

Background

Observational studies have recently associated a decrease in serum parathyroid hormone (PTH) level with a higher rate of mortality among hemodialysis (HD) patients. Decreases in PTH level can result from medical intervention (MPD) and surgical parathyroidectomy (PTX), or may occur spontaneously, usually associated with an underlying malnutrition-inflammation syndrome (SPD). The aim of our study was to prospectively identify the incidence of decreases in PTH level in a cohort of HD patients and the frequency distribution of the different causes (MPD, PTX and SPD), as well as to evaluate the survival outcomes for each PTH group (MPD, PTX and SPD) compared to patients who did not experience a PTH decrease over the first 36 months of the study (NPD).

Methods

The 197 patients receiving HD at our center in January 2010, and meeting our eligibility criteria, were enrolled in our prospective study, and were observed for a period of 60 months. A decrease in PTH level >50 % between two successive PTH measurements obtained within an interval <3 months was defined as a significant event. MPD referred to a decrease in PTH due to an increased oral calcium intake, increased dialysate calcium concentration (DCC), increased alfacalcidol use, or use of cinacalcet therapy. A surgical 7/8 PTX was performed in young patients or in patients in whom cinacalcet therapy failed. SPD referred to a decrease in PTH related to a medical or surgical event. Baseline characteristics among patients in each group (MPD, PTX, SPD, and NPD) were evaluated using Fisher’s exact test. The 60-month survival was evaluated using Kaplan-Meier and Cox multivariable proportional hazards models. Univariate and multivariate Cox analyzes were used identify variables with mortality. The relative risk of mortality was expressed as a hazard ratio (HR).

Results

The distribution of the 197 patients forming our four study groups was 34 % in the NPD group, 35 % in the SPD group, 25 % in the MSD group and 6 % in the PTX group. Among patients in the SPD group, the main acute comorbid conditions were peripheral vascular and cardiac complications, sepsis, fractures, and cancers with an increase in serum CRP level (from 14.3 ± 18 to 132 ± 90 mg/L) and a decrease in serum albumin (from 33 ± 4.5 to 28.6 ± 4 g/L). In the MPD group, the main therapeutic change was an increase in DCC, either independently or in association with cinacalcet therapy. The median survival rate among patients was 10 months for SPD, compared to 22 months among patients in the MPD group (p < 0.001). Using multivariable Cox model and taking the NPD group as reference, the risk of mortality was lower among patients in the MPD group (HR, 0.42[0.2-0.87] p = 0.01), with survival being comparable for the SPD and NPD groups (HR, 1.3 [0.75-2.2]). No mortality was observed in the PTX group.

Conclusion

The poor outcomes associated with SPD, related to acute comorbid conditions, should not lead to undertreat secondary hyperparathyroidism whose appropriate medical or surgical therapies are associated with better outcomes.

Cardiovascular calcifications in chronic kidney disease: Potential therapeutic implications

Cardiovascular (CV) calcification is a highly prevalent condition at all stages of chronic kidney disease (CKD) and is directly associated with increased CV and global morbidity and mortality. In the first part of this review, we have shown that CV calcifications represent an important part of the CKD-MBD complex and are a superior predictor of clinical outcomes in our patients. However, it is also necessary to demonstrate that CV calcification is a modifiable risk factor including the possibility of decreasing (or at least not aggravating) its progression with iatrogenic manoeuvres. Although, strictly speaking, only circumstantial evidence is available, it is known that certain drugs may modify the progression of CV calcifications, even though a direct causal link with improved survival has not been demonstrated. For example, non-calcium-based phosphate binders demonstrated the ability to attenuate the progression of CV calcification compared with the liberal use of calcium-based phosphate binders in several randomised clinical trials. Moreover, although only in experimental conditions, selective activators of the vitamin D receptor seem to have a wider therapeutic margin against CV calcification. Finally, calcimimetics seem to attenuate the progression of CV calcification in dialysis patients. While new therapeutic strategies are being developed (i.e. vitamin K, SNF472, etc.), we suggest that the evaluation of CV calcifications could be a diagnostic tool used by nephrologists to personalise their therapeutic decisions.

Advances in pharmacotherapy for hyperphosphatemia in renal disease

INTRODUCTION

Hyperphosphatemia in chronic kidney disease (CKD) is considered as an independent risk factor for surrogate clinical end points like vascular calcification (VC) and bone disease, or hard clinical outcomes like cardiovascular events. Various treatment options are available for phosphate removal or reduction. Calcium-based phosphate binders (CBB) with their possible positive calcium balance became culprits for progressive VC and increased mortality risk. Non-calcium-based binders (NCBB) treatment allowed a comparable control of hyperphosphatemia with a lower risk of hypercalcemia and a slower progression of VC. Recent data have shown a 22% risk reduction in all-cause mortality with NCBB compared to CBB treatment. The appropriate timing of phosphate binder initiation in CKD patients is still unclear. Recent reports in patients with CKD stages 3b-4 showed increased VC progression when actively treated compared to placebo and a positive calcium, but no negative phosphate balance.

AREAS COVERED

This review discusses the advantages and disadvantages of the pharmacological options to treat hyperphosphatemia.

EXPERT OPINION

The use of phosphate binders is essential in preventing morbidity and mortality in dialysis patients. The choice of phosphate binder takes into account CKD stage, the presence of other components of CKD-mineral and bone disorders, concomitant therapies and drug side-effect profile.

Adynamic bone disease: from bone to vessels in chronic kidney disease

Adynamic bone disease (ABD) is a well-recognized clinical entity in the complex chronic kidney disease (CKD)-mineral and bone disorder. Although the combination of low intact parathyroid hormone (PTH) and low bone alkaline phosphatase levels may be suggestive of ABD, the gold standard for precise diagnosis is histomorphometric analysis of tetracycline double-labeled bone biopsies. ABD essentially is characterized by low bone turnover, low bone volume, normal mineralization, and markedly decreased cellularity with minimal or no fibrosis. ABD is increasing in prevalence relative to other forms of renal osteodystrophy, and is becoming the most frequent type of bone lesion in some series. ABD develops in situations with reduced osteoanabolic stimulation caused by oversuppression of PTH, multifactorial skeletal resistance to PTH actions in uremia, and/or dysregulation of Wnt signaling. All may contribute not only to bone disease but also to the early vascular calcification processes observed in CKD. Various risk factors have been linked to ABD, including calcium loading, ageing, diabetes, hypogonadism, parathyroidectomy, peritoneal dialysis, and antiresorptive therapies, among others. The relationship between low PTH level, ABD, increased risk fracture, and vascular calcifications may at least partially explain the association of ABD with increased mortality rates. To achieve optimal bone and cardiovascular health, attention should be focused not only on classic control of secondary hyperparathyroidism but also on prevention of ABD, especially in the steadily growing proportions of diabetic, white, and elderly patients. Overcoming the insufficient osteoanabolic stimulation in ABD is the ultimate treatment goal.

Lanthanum carbonate for the control of hyperphosphatemia in chronic renal failure patients: a new oral powder formulation - safety, efficacy, and patient adherence

Chronic kidney disease (CKD) is associated with very high mortality rates, mainly of cardiovascular origin. The retention of phosphate (P) and increased fibroblast growth factor-23 levels are common, even at early stages of CKD, due to disturbances in normal P homeostasis. Later, hyperphosphatemia appears, which has also been strongly associated with high mortality rates linked to P-mediated cardiovascular and procalcifying effects. Treatment guidelines for these patients continue to be poorly implemented, at least partially due to the lack of adherence to a P-restricted diet and P-binder therapy. Calcium-free P binders, such as lanthanum carbonate, have been associated with a decreased progression of vascular calcification, rendering them an important therapeutic alternative for these high cardiovascular risk CKD patients. Lanthanum carbonate has typically been available as chewable tablets, and the new presentation as an oral powder may provide a useful alternative in the therapeutic armamentarium. This powder is a tasteless, odorless, and colorless semisolid compound miscible with food. In a recent study in healthy individuals, the safety and efficacy of this novel form were evaluated, and it was concluded that it is well tolerated and pharmacodynamically equivalent to the chewable form. In the long run, individualization of preferences and treatments seems an achievable goal prior to final demonstration of improvements in hard outcomes in wide clinical trials in CKD patients.

Effect of calcium-based versus non-calcium-based phosphate binders on mortality in patients with chronic kidney disease: an updated systematic review and meta-analysis

BACKGROUND

Phosphate binders (calcium-based and calcium-free) are recommended to lower serum phosphate and prevent hyperphosphataemia in patients with chronic kidney disease, but their effects on mortality and cardiovascular outcomes are unknown. We aimed to update our meta-analysis on the effect of calcium-based versus non-calcium-based phosphate binders on mortality in patients with chronic kidney disease.

METHODS

We did a systematic review of articles published in any language after Aug 1, 2008, up until Oct 22, 2012, by searching Medline, Embase, International Pharmaceutical Abstracts, Cochrane Central Register of Controlled Trials, and Cumulative Index to Nursing and Allied Health Literature. We included all randomised and non-randomised trials that compared outcomes between patients with chronic kidney disease taking calcium-based phosphate binders with those taking non-calcium-based binders. Eligible studies, determined by consensus with predefined criteria, were reviewed, and data were extracted onto a standard form. We combined data from randomised trials to assess the primary outcome of all-cause mortality using the DerSimonian and Laird random effects model.

FINDINGS

Our search identified 847 reports, of which eight new studies (five randomised trials) met our inclusion criteria and were added to the ten (nine randomised trials) included in our previous meta-analysis. Analysis of the 11 randomised trials (4622 patients) that reported an outcome of mortality showed that patients assigned to non-calcium-based binders had a 22% reduction in all-cause mortality compared with those assigned to calcium-based phosphate binders (risk ratio 0·78, 95% CI 0·61-0·98).

INTERPRETATION

Non-calcium-based phosphate binders are associated with a decreased risk of all-cause mortality compared with calcium-based phosphate binders in patients with chronic kidney disease. Further studies are needed to identify causes of mortality and to assess whether mortality differs by type of non-calcium-based phosphate binder.

FUNDING

None.

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.