Effect of cinacalcet on cardiovascular disease in patients undergoing dialysis

Low dialysate potassium and central arterial pressure waveform

BACKGROUND

Cardiovascular mortality is high in hemodialysis (HD) patients. Early arterial pressure wave reflections predict mortality in HD patients, and HD acutely improves the central pressure waveform. Potassium (K) plays a crucial role in cardiac electrophysiology, and patients with end-stage kidney disease depend on HD for neutral K balance. We aimed to study the impact of dialysate K concentrations on central arterial pressure waveform.

METHODS

Thirty-three chronic HD patients were studied before and after a HD session, and the prescribed dialysate K concentration was recorded. In a subset of 23 patients without arrhythmias, pulse wave analysis was performed on radial arteries. Nine patients had dialysate K set to 1 mmol/L (group 1), and 14 patients had K set to 2 or 3 mmol/L (group 2). Augmentation index (AIx), defined as difference between the second and first systolic peak divided by central pulse pressure, was used as a measure of arterial stiffness.

RESULTS

HD reduced the AIx in group 1 only (p = 0.0005). Likewise, central systolic pressure was reduced in group 1 only (p = 0.006). The relative reduction of AIx post-HD was significantly higher in group 1 compared with group 2 (p < 0.0001). The association between low dialysate K and AIx reduction remained statistically significant after adjustment for variables including the change in central and peripheral systolic pressure and mean arterial pressure.

CONCLUSION

Low dialysate K is strongly and independently associated with the acute improvement of AIx.

Randomized controlled trials 6: On contamination and estimating the actual treatment effect

The intention-to-treat analysis is the gold standard for evaluating efficacy in a randomized controlled trial. However, when non-adherence to randomized treatments is high, the actual treatment effect may be underestimated. The impact of drop-out from the intervention group or drop-in to the control group may be controlled by trial design, increasing the sample size, effective study execution, and a prespecified analytical plan to take contamination into account. These analyses may include censoring at time of co-interventions associated with stopping treatment, lag censoring which allows an additional period after discontinuation of study treatment to account for residual treatment effects, inverse probability of censoring weights (IPCW), accelerated failure time models, and contamination adjusted intent-to-treat analysis. These methods are particularly useful in assessing the "prescribed efficacy" of the study treatment, which can aid clinical decision-making.

Vitamin D and cinacalcet administration pre-transplantation predict hypercalcaemic hyperparathyroidism post-transplantation: a case-control study of 355 deceased-donor renal transplant recipients over 3 years

BACKGROUND

The effects of pre-transplantation medication for secondary hyperparathyroidism on post-transplantation parathyroid hormone (PTH) and calcium levels have not yet been conclusively determined. Therefore, this study sought to determine the level of off-label use of cinacalcet and to determine predictors of its administration during the long-term follow-up of a cohort of individuals who received deceased-donor renal transplants. Furthermore, safety considerations concerning the off-label use of cinacalcet are addressed.

METHODS

This was a case-control study of 355 stable renal transplant recipients. The patient cohort was divided into two groups. Transplant group A comprised patients who did not receive cinacalcet treatment, and transplant group B comprised patients who received cinacalcet treatment during follow-up after renal transplantation. The characteristics of the patients were evaluated to determine predictors of cinacalcet use after successful renal transplantation.

RESULTS

Compared with the control individuals (n = 300), the cinacalcet-treated individuals (n = 55) had significantly higher PTH levels at 4 weeks post-transplantation (20.3 ± 1.6 versus 40.7 ± 4.0 pmol/L, p = 0.0000) when they were drug naive. At 3.2 years post-transplantation, cinacalcet-treated patients showed higher PTH (26.2 ± 2.3 versus 18.4 ± 2.3 pmol/L, p = 0.0000), higher calcium (2.42 ± 0.03 versus 2.33 ± 0.01 mmol/L, p = 0.0045) and lower phosphate (0.95 ± 0.04 versus 1.06 ± 0.17 mmol/L, p = 0.0021) levels. Individuals in the verum group were more likely to receive cinacalcet therapy (45.5% versus 14.3%, p = 0.0000), and they had higher pill burdens for the treatment of hyperparathyroidism (1.40 ± 0.08 versus 0.72 ± 0.03 pills per patient, p = 0.0000) whilst they were on the waiting list for transplantation. Regression analysis confirmed the associations between hypercalcaemic hyperparathyroidism and PTH levels at 4 weeks post-transplantation (p = 0.0001), cinacalcet use (p = 0.0000) and the preoperative total pill burden (p = 0.0000). Renal function was the same in both groups.

CONCLUSIONS

Parathyroid gland dysfunction pre-transplantation translates into clinically relevant hyperparathyroidism post-transplantation, despite patients being administered more intensive treatment whilst on dialysis. PTH levels at 4 weeks post-transplantation might serve as a marker for the occurrence of hypercalcaemic hyperparathyroidism during follow-up.

Should we extend the application of more frequent dialysis schedules? A 'yes' and a hopeful 'no'

Observational studies associate long dialysis intervals with an excess risk for mortality and cardiovascular disease hospitalizations. The application alternate day dialysis is an appealing possibility to reduce the cardiovascular burden of long dialysis intervals and a small pilot study demonstrated that this regimen allows safe reduction of dry body weight, BP and left ventricular mass index. However, the actual impact of alternate day hemodialysis and of frequent hemodialysis in general on survival remains unknown. Frequent dialysis schedules may increase the risk of arteriovenous fistula problems and the burden of disease and eventually reduce treatment adherence. Furthermore we cannot safely exclude that more frequent dialysis regimens may be harmful. On the other hand increasing the duration of dialysis and/or frequency of hemodialysis in patients with refractory fluid overload, uncontrolled hypertension, hyperphosphatemia, malnutrition or cardiovascular disease is of unquestionable benefit in these problematic patients.Thus the moderators conclusion to the question being asked is a yes and a hopeful "no". Whenever and wherever possible we should pro-actively apply more frequent dialysis regimens, starting with the alternate day approach, in problematic patients. However, extensive application of frequent hemodialysis schedules is by now unjustified. Evidence that these regimens are beneficial mainly derives from observational studies and the possibility that frequent schedules are harmful cannot be excluded. A clinical trial is needed.

Superior predictive value for NTproBNP compared with high sensitivity cTnT in dialysis patients: a pilot prospective observational study

BACKGROUND/AIMS

The clinical utility of the new biomarker, high sensitivity cardiac T troponin (hs-cTnT) is still unclear in dialysis patients. Furthermore, the prognostic value of combining N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) and hs-cTnT has not been explored so far. The objective of this pilot study was to determine the utility of hs-cTnT alone versus hs-cTnT in combination with NT-proBNP for predicting death in a stable hemodialysis cohort.

METHODS

A prospective observational pilot study including 98 chronic asymptomatic hemodialysis patients with a follow up period of 24 months was designed. The cut-off values for NT-proBNP and hs-cTnT were calculated using receiver operating characteristic (ROC) analysis, using mortality as an end-point. Based on the cut-off values, the cohort was divided into four groups. Group 1--NT-proBNP < 14275 pg/ml and hs-cTnT < 69.48 ng/l; group 2--NT-proBNP < 14275 pg/ml and hs-cTnT > 69.48 ng/l; group 3--NT-proBNP > 14275 pg/ml and hs-cTnT < 69.48 ng/l; group 4--NT-proBNP > 14275 pg/ml and hs-cTnT > 69.48 ng/l. Survival for each group was determined using the Kaplan-Meier method and Cox regression analysis.

RESULTS

During the follow-up period 16 patients died. According to the ROC curves analysis, the cut-off point for hs-cTnT and for NT-proBNP were 69.43 ng/l (AUC = 0.618; p = 0.04) and 14275 pg/ml (AUC = 0.722; p = 0.003), respectively. In univariate Cox analysis, both hs-cTnT (HR = 3.34; p = 0.016) and NT-proBNP (HR = 5.94; p = 0.01) were predictors of death. In the multivariable Cox proportional hazards model, only NT-pro-BNP levels above the cut-off value remained an independent predictor of all-cause mortality. The combined elevation of both biomarkers did not improve significantly the prognostic value compared with NT-proBNP alone (HR = 6.15 versus HR =4 .78; p = 0.338).

CONCLUSION

NT-pro-BNP is a strong predictor of overall mortality in asymptomatic hemodialysis patients. The addition of hs-cTnT did not improve the prognostic accuracy compared with NT proBNP alone.

Association between strict blood pressure control during chronic kidney disease and lower mortality after onset of end-stage renal disease

There is controversy regarding whether strict blood pressure control is indicated in chronic kidney disease (CKD) since the primary results of randomized controlled trials failed to show any impact on progression of kidney disease with this strategy. However, strict blood pressure control may have other beneficial effects beyond reducing the risk of end-stage renal disease (ESRD), such as lowering mortality after ESRD onset. The Modification of Diet in Renal Disease (MDRD) trial randomized 840 patients with CKD to strict (mean arterial pressure under 92 mm Hg) versus usual (mean arterial pressure under 107 mm Hg) blood pressure control between 1989 and 1993. Here we extended follow-up of study enrollees by linkage with United States Renal Data System and National Death Index to ascertain ESRD and vital status through 2010. Overall, 627 patients developed ESRD through 2010 with a median follow-up of 19.3 years. After ESRD onset, there were 142 deaths in the strict blood pressure arm and 182 deaths in the usual blood pressure arm (significant unadjusted hazard ratio for death was 0.72 (95% CI 0.58-0.89)). Overall, there were 212 deaths in the strict blood pressure control arm and 233 deaths in the usual arm (significant unadjusted hazard ratio for death 0.82 (95% CI 0.68-0.98)). Thus, although strict blood pressure control did not delay progression of CKD to ESRD, this strategy was associated with a lower risk of death after ESRD. Hence, long-term post-ESRD outcomes should be considered when formulating blood pressure targets for CKD.

Calcimimetics for secondary hyperparathyroidism in chronic kidney disease patients

BACKGROUND

Calcimimetic agents lower abnormal serum parathyroid hormone (PTH) levels in people who have chronic kidney disease (CKD), but the benefits and harms on patient-level outcomes are uncertain. Since this review was first published in 2006 showing that evidence for calcimimetics was largely restricted to biochemical outcomes, additional studies have been conducted. This is an update of a review first published in 2006.

OBJECTIVES

To evaluate the benefits and harms of cinacalcet on patient-level outcomes in adults with CKD.

SEARCH METHODS

MEDLINE, EMBASE, CENTRAL and conference proceedings were searched for randomised controlled trials (RCTs) evaluating any calcimimetic against placebo or another agent in adults with CKD (persistent albuminuria > 30 mg/g with or without reduced glomerular filtration rate (GFR) (below 60 mL/min/1.73 m²)). We updated searches to 7 February 2013 including the Cochrane Renal Group's Specialised Register to complete this update.

SELECTION CRITERIA

We included all RCTs of a calcimimetic administered to patients with CKD for the treatment of elevated serum PTH levels.

DATA COLLECTION AND ANALYSIS

Data were extracted on all relevant patient-centred and surrogate outcomes. We summarised treatment estimates using random effects and expressed treatment effects as a risk ratio (RR) or mean difference (MD) with 95% confidence intervals (CI).

MAIN RESULTS

Eighteen studies (7446 participants) compared cinacalcet in addition to standard therapy with no treatment or placebo plus standard therapy. In adults with GFR category G5 (GFR below 15 mL/min/1.73 m²) treated with dialysis, routine cinacalcet treatment had little or no effect on all-cause mortality (RR 0.97, 95% CI 0.89 to 1.05), imprecise effects on cardiovascular mortality (RR 0.67, 95% CI 0.16 to 2.87), and prevented surgical parathyroidectomy (RR 0.49, 95% CI 0.40 to 0.59) and hypercalcaemia (RR 0.23, 95% CI 0.05 to 0.97), but increased hypocalcaemia (RR 6.98, 95% CI 5.10 to 9.53), nausea (RR 2.02, 95% CI 1.45 to 2.81) and vomiting (RR 1.97, 95% CI 95% CI 1.73 to 2.24). Cinacalcet decreased serum PTH (MD -281.39 pg/mL, 95% CI -325.84 to -234.94) and calcium (MD -0.87 mg/dL, 95% CI -0.96 to -0.77) levels, but had little or no effect on serum phosphorous levels (MD -0.23 mg/dL, 95% CI -0.58 to 0.12).Data were sparse for adults with GFR categories G3a to G4 (GFR 15 to 60 mL/min/1.73 m²) and kidney transplant recipients.Overall, based on GRADE criteria, evidence for cinacalcet in adults with GFR category G5 treated with dialysis (mortality, parathyroidectomy, hypocalcaemia, and nausea) is of high or moderate quality. High quality evidence suggests "further research is very unlikely to change our confidence in the estimate of treatment effect" and moderate quality evidence is "further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate". Information for adults with less severe CKD GFR category G3a to G4 is of low or very low quality. This means that further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate

AUTHORS' CONCLUSIONS

Routine cinacalcet therapy reduced the need for parathyroidectomy in adults treated with dialysis and elevated PTH levels but does not improve all-cause or cardiovascular mortality. Cinacalcet increases risks of nausea, vomiting and hypocalcaemia, suggesting harms may outweigh benefits in this population.

Calcific uraemic arteriolopathy: a rare disease with a potentially high impact on chronic kidney disease-mineral and bone disorder

Calciphylaxis [calcific uraemic arteriolopathy (CUA)] is a rare disease at the interface of nephrology, dermatology and cardiology. CUA most often occurs in adult dialysis patients. It is only rarely seen in patients without relevant chronic kidney disease, and only anecdotal reports about childhood calciphylaxis have been published. Clinically, CUA is characterized by a typical cascade, starting with severe pain in initially often inconspicuous skin areas, followed by progressive cutaneous lesions that may develop into deep tissue ulcerations. The typical picture is a mixture of large retiform ulceration with thick eschar surrounded by violaceous, indurated, tender plaques. The histopathological picture reveals arteriolar, often circumferential, calcification and extensive matrix remodelling of the subcutis. These findings explain the macroscopic correlation between skin induration and ulceration. The prognosis in CUA patients is limited due to underlying comorbidities such as uraemic cardiovascular disease and infectious complications. The etiology of CUA is multifactorial, and imbalances between pro- and anti-calcification factors, especially in the setting of end-stage renal disease play an outstanding role. Oral anticoagulant treatment with vitamin K antagonists is a predominant CUA trigger factor. It is speculative as to why children and adolescents only develop calciphylaxis in exceptional cases, although a seldom usage of vitamin K antagonists and the preserved mineral buffering capacity of the growing skeleton may be protective.

Effects of cinacalcet on atherosclerotic and nonatherosclerotic cardiovascular events in patients receiving hemodialysis: the EValuation Of Cinacalcet HCl Therapy to Lower CardioVascular Events (EVOLVE) trial

Background

Premature cardiovascular disease limits the duration and quality of life on long‐term hemodialysis. The objective of this study was to define the frequency of fatal and nonfatal cardiovascular events attributable to atherosclerotic and nonatherosclerotic mechanisms, risk factors for these events, and the effects of cinacalcet, using adjudicated data collected during the EValuation of Cinacalcet HCl Therapy to Lower CardioVascular Events (EVOLVE) Trial.

Methods and Results

EVOLVE was a randomized, double‐blind, placebo‐controlled clinical trial that randomized 3883 hemodialysis patients with moderate to severe secondary hyperparathyroidism to cinacalcet or matched placebo for up to 64 months. For this post hoc analysis, the outcome measure was fatal and nonfatal cardiovascular events reflecting atherosclerotic and nonatherosclerotic cardiovascular diseases. During the trial, 1518 patients experienced an adjudicated cardiovascular event, including 958 attributable to nonatherosclerotic disease. Of 1421 deaths during the trial, 768 (54%) were due to cardiovascular disease. Sudden death was the most frequent fatal cardiovascular event, accounting for 24.5% of overall mortality. Combining fatal and nonfatal cardiovascular events, randomization to cinacalcet reduced the rates of sudden death and heart failure. Patients randomized to cinacalcet experienced fewer nonatherosclerotic cardiovascular events (adjusted relative hazard 0.84, 95% CI 0.74 to 0.96), while the effect of cinacalcet on atherosclerotic events did not reach statistical significance.

Conclusions

Accepting the limitations of post hoc analysis, any benefits of cinacalcet on cardiovascular disease in the context of hemodialysis may result from attenuation of nonatherosclerotic processes.

Clinical Trials Registration

Unique identifier: NCT00345839. URL: ClinicalTrials.gov.

Sudden cardiac death in end stage renal disease: unlocking the mystery

Sudden cardiac death (SCD) is a major cause of concern in end stage renal disease (ESRD), contributing to 70% of cardiovascular mortality and 27% of all-cause mortality in dialysis patients. Yet its mechanisms and pathogenesis remain largely obscure. This review discusses the potential reasons for an exaggerated risk of SCD in ESRD populations taking into account recent studies and registry data and additionally explores the reasons for the reported recent decline in SCD. The types of arrhythmias typical of the hemodialysis population are yet to be fully characterised and in this paper, we introduce an ongoing implantable loop recorder (ILR) based study in hemodialysis patients--CRASH ILR (Cardio Renal Arrhythmia Study in Haemodialysis patients using Implantable Loop Recorders). The findings of this study will hopefully guide the design and implementation of larger ILR based studies before undertaking larger scale interventional therapeutic trials in this high risk population.

A randomized study evaluating cinacalcet to treat hypercalcemia in renal transplant recipients with persistent hyperparathyroidism

Persistent hyperparathyroidism (HPT) after kidney transplantation (KTx) is associated with hypercalcemia, hypophosphatemia and abnormally high levels of parathyroid hormone (PTH). In this randomized trial, cinacalcet was compared to placebo for the treatment of hypercalcemia in adult patients with persistent HPT after KTx. Subjects were randomized 1:1 to cinacalcet or placebo with randomization stratified by baseline corrected total serum calcium levels (≤11.2 mg/dL [2.80 mmol/L] or >11.2 mg/dL [2.80 mmol/L]). The primary end point was achievement of a mean corrected total serum calcium value<10.2 mg/dL (2.55 mmol/L) during the efficacy period. The two key secondary end points were percent change in bone mineral density (BMD) at the femoral neck and absolute change in phosphorus; 78.9% cinacalcet- versus 3.5% placebo-treated subjects achieved the primary end point with a difference of 75.4% (95% confidence interval [CI]: 63.8, 87.1), p<0.001. There was no statistical difference in the percent change in BMD at the femoral neck between cinacalcet and placebo groups, p=0.266. The difference in the change in phosphorus between the two arms was 0.45 mg/dL (95% CI: 0.26, 0.64), p<0.001 (nominal). No new safety signals were detected. In conclusion, hypercalcemia and hypophosphatemia were effectively corrected after treatment with cinacalcet in patients with persistent HPT after KTx.

Bone histomorphometry before and after long-term treatment with cinacalcet in dialysis patients with secondary hyperparathyroidism

The multicenter, single-arm BONAFIDE study characterized the skeletal response to cinacalcet in adult dialysis patients with plasma parathyroid hormone (PTH) levels of 300 pg/ml or more, serum calcium of 8.4 mg/dl or more, bone-specific alkaline phosphatase over 20.9 ng/ml and biopsy-proven high-turnover bone disease. Of 110 enrolled patients, 77 underwent a second bone biopsy with quantitative histomorphometry after 6-12 months of cinacalcet treatment. The median PTH decreased from 985 pg/ml at baseline to 480 pg/ml at the end of study (weeks 44-52). Bone formation rate/tissue area decreased from 728 to 336 μm(2)/mm(2)/day, osteoblast perimeter/osteoid perimeter decreased from 17.4 to 13.9%, and eroded perimeter/bone perimeter decreased from 12.7 to 8.3%. The number of patients with normal bone histology increased from none at baseline to 20 at 12 months. Two patients had adynamic bone at the end of study with a PTH under 150 pg/ml, and one patient with overt hypophosphatemia at baseline that reoccurred during follow-up developed osteomalacia. Thus, long-term treatment with cinacalcet substantially reduced PTH, diminished the elevated bone formation rate/tissue area, lowered several biochemical markers of high-turnover bone disease toward normal, and generally improved bone histology. Twenty patients had normal bone histology at follow-up, whereas most had mild hyperparathyroidism or mixed uremic osteodystrophy.

Phosphate management in chronic kidney disease

PURPOSE OF REVIEW

The review focuses on the rationale and evidence behind management strategies for hyperphosphatemia in patients with chronic kidney disease (CKD).

RECENT FINDINGS

Optimal management of phosphate in CKD remains an area of uncertainty, but multiple studies now point to a clinical benefit from the use of phosphate binders. Evidence of improved survival is particularly strong with sevelamer, though it remains unclear whether the absence of calcium or other properties of sevelamer are responsible for this relationship. Newer agents, such as iron-based binders or niacin compounds to inhibit phosphorus absorption, may have additional benefits which will be better defined with additional experience. A reduced pill count may be a particularly beneficial characteristic of newer agents, and has been associated with improved response to therapy. Increased use of frequent, nocturnal hemodialysis is an additional tool to help ameliorate phosphate control. Data on the reduction of fibroblast growth factor 23 through use of phosphate binders remain weak.

SUMMARY

An improved understanding of phosphate regulation and the development of new therapeutic agents have reinvigorated a once stagnant field, but significant changes to practice cannot yet be justified. There is increasing support for using sevelamer in place of calcium-based binders, though economic practicability remains challenging.

Phosphate balance in ESRD: diet, dialysis and binders against the low evident masked pool

Phosphate metabolism is crucial in the pathophysiology of secondary hyperparathyroidism and vascular calcification. High phosphate levels have been consistently associated with unfavorable outcomes in dialysis patients, but several limitations are still hampering a resolutive definition of the optimal targets of phosphate serum levels to be achieved in this cohort. Nonetheless, hyperphosphatemia is a late marker of phosphate overload in humans. Clinical nephrologists routinely counteract the positive phosphate balance in dialysis patients through nutritional counseling, stronger phosphate removal by dialysis and prescription of phosphate binders. However, the superiority against placebo of phosphate control by diet, dialysis or binders in terms of survival has never been tested in dedicated randomized controlled trials. The present review discusses this conundrum with particular emphasis on the rationale supporting the value of a simultaneous intervention against phosphate overload in dialysis patients via the improvement of dietary intakes, dialysis efficiency and an individualized choice of phosphate binders.

Targets for parathyroid hormone in secondary hyperparathyroidism: is a "one-size-fits-all" approach appropriate? A prospective incident cohort study

BACKGROUND

Recommendations for secondary hyperparathyroidism (SHPT) consider that a "one-size-fits-all" target enables efficacy of care. In routine clinical practice, SHPT continues to pose diagnosis and treatment challenges. One hypothesis that could explain these difficulties is that dialysis population with SHPT is not homogeneous.

METHODS

EPHEYL is a prospective, multicenter, pharmacoepidemiological study including chronic dialysis patients (≥ 3 months) with newly SHPT diagnosis, i.e. parathyroid hormone (PTH) ≥ 500 ng/L for the first time, or initiation of cinacalcet, or parathyroidectomy. Multiple correspondence analysis and ascendant hierarchical clustering on clinico-biological (symptoms, PTH, plasma phosphorus and alkaline phosphatase) and treatment of SHPT (cinacalcet, vitamin D, calcium, or calcium-free calcic phosphate binder) were performed to identify distinct phenotypes.

RESULTS

305 patients (261 with incident PTH ≥ 500 ng/L; 44 with cinacalcet initiation) were included. Their mean age was 67 ± 15 years, and 60% were men, 92% on hemodialysis and 8% on peritoneal dialysis. Four subgroups of SHPT patients were identified: 1/ "intermediate" phenotype with hyperphosphatemia without hypocalcemia (n = 113); 2/ younger patients with severe comorbidities, hyperphosphatemia and hypocalcemia, despite SHPT multiple medical treatments, suggesting poor adherence (n = 73); 3/ elderly patients with few cardiovascular comorbidities, controlled phospho-calcium balance, higher PTH, and few treatments (n = 75); 4/ patients who initiated cinacalcet (n = 43). The quality criterion of the model had a cut-off of 14 (>2), suggesting a relevant classification.

CONCLUSION

In real life, dialysis patients with newly diagnosed SHPT constitute a very heterogeneous population. A "one-size-fits-all" target approach is probably not appropriate. Therapeutic management needs to be adjusted to the 4 different phenotypes.

Quantifying a rare disease in administrative data: the example of calciphylaxis

BACKGROUND

Calciphylaxis, a rare disease seen in chronic dialysis patients, is associated with significant morbidity and mortality. As is the case with other rare diseases, the precise epidemiology of calciphylaxis remains unknown. Absence of a unique International Classification of Diseases (ICD) code impedes its identification in large administrative databases such as the United States Renal Data System (USRDS) and hinders patient-oriented research. This study was designed to develop an algorithm to accurately identify cases of calciphylaxis and to examine its incidence and mortality.

DESIGN, PARTICIPANTS, AND MAIN MEASURES

Along with many other diagnoses, calciphylaxis is included in ICD-9 code 275.49, Other Disorders of Calcium Metabolism. Since calciphylaxis is the only disorder listed under this code that requires a skin biopsy for diagnosis, we theorized that simultaneous application of code 275.49 and skin biopsy procedure codes would accurately identify calciphylaxis cases. This novel algorithm was developed using the Partners Research Patient Data Registry (RPDR) (n = 11,451 chronic hemodialysis patients over study period January 2002 to December 2011) using natural language processing and review of medical and pathology records (the gold-standard strategy). We then applied this algorithm to the USRDS to investigate calciphylaxis incidence and mortality.

KEY RESULTS

Comparison of our novel research strategy against the gold standard yielded: sensitivity 89.2%, specificity 99.9%, positive likelihood ratio 3,382.3, negative likelihood ratio 0.11, and area under the curve 0.96. Application of the algorithm to the USRDS identified 649 incident calciphylaxis cases over the study period. Although calciphylaxis is rare, its incidence has been increasing, with a major inflection point during 2006-2007, which corresponded with specific addition of calciphylaxis under code 275.49 in October 2006. Calciphylaxis incidence continued to rise even after limiting the study period to 2007 onwards (from 3.7 to 5.7 per 10,000 chronic hemodialysis patients; r = 0.91, p = 0.02). Mortality rates among calciphylaxis patients were noted to be 2.5-3 times higher than average mortality rates for chronic hemodialysis patients.

CONCLUSIONS

By developing and successfully applying a novel algorithm, we observed a significant increase in calciphylaxis incidence. Because calciphylaxis is associated with extremely high mortality, our study provides valuable information for future patient-oriented calciphylaxis research, and also serves as a template for investigating other rare diseases.

Recent advances in the management of hemodialysis patients: a focus on cardiovascular disease

The number of patients requiring chronic hemodialysis is rapidly growing worldwide. Hemodialysis both greatly reduces quality of life and is associated with extremely high mortality rates. Management of care of patients requiring chronic hemodialysis is complex, and randomized controlled trials aimed at reducing primary outcomes of cardiovascular disease events, mortality, or both in this population have largely been unsuccessful. Topics of major concern in the management of maintenance hemodialysis patients as related to these outcomes include the overall cardiovascular disease burden, blood pressure control, anemia, abnormalities in mineral metabolism, and inflammation. The focus of this review is a discussion of these topics on the basis of current recommendations from major organizations, expert opinion, and the available randomized controlled trials to date. These issues are further complicated by sometimes conflicting observational and randomized controlled trial data. Overall, treatment options for reducing these endpoints in maintenance hemodialysis patients are limited, and future randomized controlled trials are essential to continuing to advance care in this population, with the goal of ultimately improving hard outcomes. Such trials should consider new therapies to better target these factors, additional risk factors that have not been well tested to date, and therapies with new targets, including inflammation.

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

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

Reforming medicare's dialysis payment policies: implications for patients with secondary hyperparathyroidism

OBJECTIVE

To demonstrate how expanding services covered by a "bundled payment" can also expand variation in the costs of treating patients under the bundle, using the Medicare dialysis program as an example.

DATA SOURCES/STUDY SETTING

Observational claims-based study of 197,332 Medicare hemodialysis beneficiaries enrolled for at least one quarter during 2006-2008.

STUDY DESIGN

We estimated how resource utilization (all health services, dialysis-related services, and medications) changes with intensity of secondary hyperparathyroidism (sHPT) treatment.

DATA EXTRACTION METHODS

Using Medicare claims, a patient-quarter level dataset was constructed, including a measure of sHPT treatment intensity.

PRINCIPAL FINDINGS

Under the existing, narrow dialysis bundle, utilization of covered services is relatively constant across treatment intensity groups; under a broader bundle, it rises more rapidly with treatment intensity.

CONCLUSIONS

The broader Medicare dialysis bundle reimburses providers uniformly, even though patients treated more intensively for sHPT cost more to treat. Absent any payment adjustments or efforts to ensure quality, this flat payment schedule may encourage providers to avoid high-intensity patients or reduce their treatment intensity. The first incentive harms efficiency. The second may improve or worsen efficiency, depending on whether it reduces appropriate or inappropriate treatment.

Evidence for the prevention and treatment of stroke in dialysis patients

The risks of both ischemic and hemorrhagic stroke are particularly high in dialysis patients of any age and outcomes are poor. It is therefore important to identify strategies that safely minimize stroke risk in this population. Observational studies have been unable to clarify the relative importance of traditional stroke risk factors such as blood pressure and cholesterol in those on dialysis, and are affected by biases that usually make them an inappropriate source of data on which to base therapeutic decisions. Well-conducted randomized trials are not susceptible to such biases and can reliably investigate the causal nature of the association between a potential risk factor and the outcome of interest. However, dialysis patients have been under-represented in the cardiovascular trials which have proven net benefit of commonly used preventative treatments (e.g., antihypertensive treatments, low-dose aspirin, carotid revascularization, and thromboprophylaxis for atrial fibrillation), and there remains uncertainty about safety and efficacy of many of these treatments in this high-risk population. Moreover, the efficacy of renal-specific therapies that might reduce cardiovascular risk, such as modulators of mineral and bone disorder, online hemodiafiltration, and daily (nocturnal) hemodialysis, have not been tested in adequately powered trials. Recent trials have also demonstrated how widespread current practices could be causing stroke. Therefore, it is important that reliable information on the prevention and treatment of stroke (and other cardiovascular disease) in dialysis patients is generated by performing large-scale randomized trials of many current and future treatments.

The use of fibroblast growth factor 23 testing in patients with kidney disease

The emergence of fibroblast growth factor 23 as a potentially modifiable risk factor in CKD has led to growing interest in its measurement as a tool to assess patient risk and target therapy. This review discusses the analytical and clinical challenges faced in translating fibroblast growth factor 23 testing into routine practice. As for other bone mineral markers, agreement between commercial fibroblast growth factor 23 assays is poor, mainly because of differences in calibration, but also, these differences reflect the variable detection of hormone fragments. Direct comparison of readout from different assays is consequently limited and likely hampers setting uniform fibroblast growth factor 23-directed targets. Efforts are needed to standardize assay output to enhance clinical use. Fibroblast growth factor 23 is robustly associated with cardiovascular and renal outcomes in patients with CKD and adds value to risk assessments based on conventional risk factors. Compared with most other mineral markers, fibroblast growth factor 23 shows better intraindividual temporal stability, with minimal diurnal and week-to-week variability, but substantial interindividual variation, maximizing discriminative power for risk stratification. Conventional therapeutic interventions for the CKD-mineral bone disorder, such as dietary phosphate restriction and use of oral phosphate binders or calcimimetics, are associated with variable efficacy at modulating circulating fibroblast growth factor 23 concentrations, like they are for other mineral metabolites. Dual therapy with dietary phosphate restriction and noncalcium-based binder use achieves the most consistent fibroblast growth factor 23-lowering effect and seems best monitored using an intact assay. Additional studies are needed to evaluate whether strategies aimed at reducing levels or antagonizing its action have beneficial effects on clinical outcomes in CKD patients. Moreover, a better understanding of the mechanisms driving fibroblast growth factor 23 elevations in CKD is needed to inform the use of therapeutic interventions targeting fibroblast growth factor 23 excess. This evidence must be forthcoming to support the use of fibroblast growth factor 23 measurement and fibroblast growth factor 23-directed therapy in the clinic.

Associations of FGF-23 and sKlotho with cardiovascular outcomes among patients with CKD stages 2-4

BACKGROUND AND OBJECTIVES

CKD-mineral and bone disorders (CKD-MBD) measures contribute to cardiovascular morbidity in patients with CKD. Among these, fibroblast growth factor (FGF)-23 and its coreceptor Klotho may exert direct effects on vascular and myocardial tissues. Klotho exists in a membrane-bound and a soluble form (sKlotho). Recent experimental evidence suggests sKlotho has vasculoprotective functions.

DESIGN, SETTINGS, PARTICIPANTS, & MEASUREMENTS

Traditional and novel CKD-MBD variables were measured among 444 patients with CKD stages 2-4 recruited between September 2008 and November 2012 into the ongoing CARE FOR HOMe study. Across tertiles of baseline sKlotho and FGF-23, the incidence of two distinct combined end points was analyzed: (1) the first occurrence of an atherosclerotic event or death from any cause and (2) the time until hospital admission for decompensated heart failure or death from any cause.

RESULTS

Patients were followed for 2.6 (interquartile range, 1.4-3.6) years. sKlotho tertiles predicted neither atherosclerotic events/death (fully adjusted Cox regression analysis: hazard ratio [HR] for third versus first sKlotho tertile, 0.75 [95% confidence interval (95% CI), 0.43-1.30]; P=0.30) nor the occurrence of decompensated heart failure/death (HR for third versus first sKlotho tertile, 0.81 [95% CI, 0.39-1.66]; P=0.56). In contrast, patients in the highest FGF-23 tertile had higher risk for both end points in univariate analysis. Adjustment for kidney function attenuated the association between FGF-23 and atherosclerotic events/death (HR for third versus first FGF-23 tertile, 1.23 [95% CI, 0.58-2.61]; P=0.59), whereas the association between FGF-23 and decompensated heart failure/death remained significant after adjustment for confounders (HR for third versus first FGF-23 tertile, 4.51 [95% CI, 1.33-15.21]; P=0.02).

CONCLUSIONS

In this prospective observational study of limited sample size, sKlotho was not significantly related to cardiovascular outcomes. FGF-23 was significantly associated with future decompensated heart failure but not incident atherosclerotic events.

Are there ways to attenuate arterial calcification and improve cardiovascular outcomes in chronic kidney disease?

The risk of cardiovascular mortality among patients with end-stage renal disease is several times higher than general population. Arterial calcification, a marker of atherosclerosis and a predictor of cardiovascular mortality, is common in chronic kidney disease (CKD). The presence of traditional cardiovascular risk factors such as diabetes, hypertension, hyperlipidemia, and advanced age cannot fully explain the high prevalence of atherosclerosis and arterial calcification. Other factors specific to CKD such as hyperphosphatemia, excess of calcium, high dose active vitamin D and prolonged dialysis vintage play important roles in the development of arterial calcification. Due to the significant health risk, it is prudent to attempt to lower arterial calcification burden in CKD. Treatment of hyperlipidemia with statin has failed to lower atherosclerotic and arterial calcification burden. Data on diabetes and blood pressure controls as well as smoking cessation on cardiovascular outcomes in CKD population are limited. Currently available treatment options include non-calcium containing phosphate binders, low dose active vitamin D, calcimimetic agent and perhaps bisphosphonates, vitamin K and sodium thiosulfate. Preliminary data on bisphosphonates, vitamin K and sodium thiosulfate are encouraging but larger studies on efficacy and outcomes are needed.

Epidemiology, contributors to, and clinical trials of mortality risk in chronic kidney failure

Patients with chronic kidney failure--defined as a glomerular filtration rate persistently below 15 mL/min per 1·73 m(2)--have an unacceptably high mortality rate. In developing countries, mortality results primarily from an absence of access to renal replacement therapy. Additionally, cardiovascular and non-cardiovascular mortality are several times higher in patients on dialysis or post-renal transplantation than in the general population. Mortality of patients on renal replacement therapy is affected by a combination of socioeconomic factors, pre-existing medical disorders, renal replacement treatment modalities, and kidney failure itself. Characterisation of the key pathophysiological contributors to increased mortality and cardiorenal risk staging systems are needed for the rational design of clinical trials aimed at decreasing mortality. Policy changes to improve access to renal replacement therapy should be combined with research into low-cost renal replacement therapy and optimum clinical care, which should include multifaceted approaches simultaneously targeting several of the putative contributors to increased mortality.

Patient satisfaction with in-centre haemodialysis care: an international survey

OBJECTIVES

To evaluate patient experiences of specific aspects of haemodialysis care across several countries.

DESIGN

Cross-sectional survey using the Choices for Healthy Outcomes in Caring for End-Stage Renal Disease (CHOICE) questionnaire.

SETTING

Haemodialysis clinics within a single provider in Europe and South America.

PARTICIPANTS

2748 adults treated in haemodialysis.

PRIMARY AND SECONDARY OUTCOMES

The primary outcome was patient satisfaction with overall care. Secondary outcomes included patient experiences of individual aspects of dialysis care.

RESULTS

2145 (78.1%) adults responded to the questionnaire. Fewer than half (46.5% (95% CI 44.5% to 48.6%)) rated their overall care as excellent. Global perceptions of care were uninfluenced by most respondent characteristics except age and depressive symptoms; older respondents were less critical of their care (adjusted OR for excellent rating 1.44 (1.01 to 2.04)) and those with depressive symptoms were less satisfied (0.56 (0.44 to 0.71)). Aspects of care that respondents most frequently ranked as excellent were staff attention to dialysis vascular access (54% (52% to 56%)); caring of nurses (53% (51% to 55%)); staff responsiveness to pain or discomfort (51% (49% to 53%)); caring, helpfulness and sensitivity of dialysis staff (50% (48% to 52%)); and ease of reaching dialysis staff by telephone (48% (46% to 50%)). The aspects of care least frequently ranked as excellent were information provided when choosing a dialysis modality (23% (21% to 25%)), ease of seeing a social worker (28% (24% to 32%)), information provided about dialysis (34% (32% to 36%)), accuracy of information from nephrologist (eg, about prognosis or likelihood of a kidney transplant; 37% (35% to 39%)) and accuracy of nephrologists' instructions (39% (36% to 41%)).

CONCLUSIONS

Haemodialysis patients are least satisfied with the complex aspects of care. Patients' expectations for accurate information, prognosis, the likelihood of kidney transplantation and their options when choosing dialysis treatment need to be considered when planning healthcare research and practices.

Regression of vascular calcification in chronic kidney disease - feasible or fantasy? a review of the clinical evidence

The complex relationships between cardiovascular, renal, and bone disease are increasingly recognized but not yet clearly understood. Vascular calcification (VC) represents a common end point between these interlinked systems. It is highly prevalent in chronic kidney disease (CKD) and may be responsible for some of the excess cardiovascular events seen in this condition. There is much interest in developing therapeutic agents to stop its development or reverse its progression. Traditionally considered to be due to abnormalities in calcium and phosphate metabolism alone, VC is now known to be the product of active, dynamic processes within the vessel wall. Primary prevention of VC is possible through successful prevention or reversal of progressive renal dysfunction, hypertension and hyperlipidaemia, but is challenging given the increasing global prevalence of these risk factors. Secondary prevention of VC through tight control of calcium and phosphate, can be achieved by dietary or pharmacological means. Both the modification of haemodialysis duration or methods and the use of renal transplantation have an effect. Novel drugs such as cinacalcet were hoped to halt calcification but results have been mixed, and no intervention has yet been shown to reverse calcification reliably. A new range of experimental targets involved in the putative mediatory pathways between bone and vascular disease has emerged. Aiming to manipulate the active mechanisms involved in calcium deposition, these hold hope for reversal of calcification, but are still theoretical or in early animal or human experimentation.

Coronary artery calcification in chronic kidney disease: An update

Arterial calcification is a well-recognized complication of advanced atherosclerosis. Chronic kidney disease (CKD) is characterized by significantly more pronounced, disseminated and fast-progressing calcification of the vascular system, including the coronary arteries. New computed tomography-based imaging techniques allow for the noninvasive assessment and monitoring of calcification in different vascular sites. Coronary artery calcification (CAC) develops early in the course of CKD and is tightly associated with mineral and bone disorders, which include but are not limited to secondary hyperparathyroidism. In this review, recent data on the pathogenesis of CAC development and progression are discussed, with a special emphasis on fibroblast growth factor 23 and its co-receptor, klotho. The prevalence, progression and prognostic significance of CAC are reviewed separately for patients with end-stage renal disease treated with dialysis, kidney transplant recipients and patients with earlier stages of CKD. In the last section, therapeutic considerations are discussed, with special attention paid to the importance of treatment that addresses mineral and bone disorders of CKD.

Cinacalcet treatment decreases plasma fibroblast growth factor 23 concentration in haemodialysed patients with chronic kidney disease and secondary hyperparathyroidism

OBJECTIVE

Recent clinical studies suggest that fibroblast growth factor 23 (FGF23) is important in the pathogenesis of calcium-phosphate abnormalities in patients with chronic kidney disease and that increased plasma FGF23 concentration is a cardiovascular risk factor in these patients. The aim of this prospective, single-arm, open-label clinical study was to assess the influence of 6-month cinacalcet treatment on plasma FGF23 concentration in haemodialysed patients with secondary hyperparathyroidism (sHPT).

DESIGN, PATIENTS AND MEASUREMENTS

In 58 haemodialysed patients with sHPT (parathormone PTH > 300 ng/l), serum PTH, FGF23, calcium and phosphate concentrations were assessed before the first dose of cinacalcet and after 3 and 6 months of treatment.

RESULTS

Serum PTH concentration decreased significantly after 3 and 6 months of treatment, and the mean serum calcium and phosphate concentrations remained stable during the treatment period. Plasma FGF23 concentration (geometric mean with 95% confidence index) decreased after 3 and 6 months of treatment from 354 (261-481) ng/l to 295 (204-428) ng/l; P = 0·099 and to 183 (117-285) ng/l; P = 0·015, respectively. FGF23 concentration decreased in 52% of patients. In multivariate regression analysis, plasma FGF23 concentration changes were explained by the changes in serum phosphate, but not by serum PTH or calcium changes or by the dose of cinacalcet.

CONCLUSIONS

1. Cinacalcet treatment decreases plasma FGF23 concentration in haemodialysed patients with secondary hyperparathyroidism. 2. The decrease in plasma FGF23 concentration seems to be related to the decrease in serum phosphate concentration.

Mortality of combined serum phosphorus and parathyroid hormone concentrations and their changes over time in hemodialysis patients

BACKGROUND

Mineral and bone disorder (MBD) is common and associated with mortality in patients with chronic kidney disease (CKD) Given that disarrays in serum phosphorus (P) and parathyroid hormone (PTH) levels and their changes over time are closely interrelated, modeling mortality-predictability of their combinations may help improve CKD patient management.

METHODS

A historical cohort study was undertaken to evaluate the joint effect of serum P and PTH levels on mortality in 107,299 chronic hemodialysis (HD) patients. Changes in serum P and PTH levels over 6months, in particular discordant changes, were also modeled with mortality.

RESULTS

HD patients were 64±15 (mean±SD)years old and included 45% women, 33% African-American, and 59% diabetic. Compared with serum P level ≥7.0mg/dL and PTH level ≥600pg/mL, adjusted hazard ratio (HR) tended to be lowest in patients with serum P level of 3.5-<5.5mg/dL combined with PTH level of 150-<300pg/mL (HR 0.64, 95% confidence interval 0.61-0.67). A change over time in serum P level towards the 3.5-<5.5mg/dL range from higher or lower ranges was associated with a decreased mortality, whereas only change in PTH level from <150pg/mL to 150-<300pg/mL range was associated with a lower risk of mortality. Upon discordant changes of PTH and P, i.e., decrease in one of the two measures while the other increased, no change in mortality risk was observed.

CONCLUSION

In CKD-MBD management, patent survival is the greatest with controlling both serum P and PTH levels in balance. Tailoring an individualized treatment strategy in CKD-MBD may benefit patients. Further studies are needed.

A comparison of calcium to zoledronic acid for improvement of cortical bone in an animal model of CKD

Patients with chronic kidney disease (CKD) have increased risk of fractures, yet the optimal treatment is unknown. In secondary analyses of large randomized trials, bisphosphonates have been shown to improve bone mineral density and reduce fractures. However, bisphosphonates are currently not recommended in patients with advanced kidney disease due to concern about oversuppressing bone remodeling, which may increase the risk of developing arterial calcification. In the present study we used a naturally occurring rat model of CKD with secondary hyperparathyroidism, the Cy/+ rat, and compared the efficacy of treatment with zoledronic acid, calcium given in water to simulate a phosphate binder, and the combination of calcium and zoledronic acid. Animals were treated beginning at 25 weeks of age (approximately 30% of normal renal function) and followed for 10 weeks. The results demonstrate that both zoledronic acid and calcium improved bone volume by micro-computed tomography (µCT) and both equally suppressed the mineral apposition rate, bone formation rate, and mineralizing surface of trabecular bone. In contrast, only calcium treatment with or without zoledronic acid improved cortical porosity and cortical biomechanical properties (ultimate load and stiffness) and lowered parathyroid hormone (PTH). However, only calcium treatment led to the adverse effects of increased arterial calcification and fibroblast growth factor 23 (FGF23). These results suggest zoledronic acid may improve trabecular bone volume in CKD in the presence of secondary hyperparathyroidism, but does not benefit extraskeletal calcification or cortical biomechanical properties. Calcium effectively reduces PTH and benefits both cortical and trabecular bone yet increases the degree of extra skeletal calcification. © 2014 American Society for Bone and Mineral Research.

Parathyroidectomy improves cardiovascular outcome in nondiabetic dialysis patients with secondary hyperparathyroidism

OBJECTIVE

Secondary hyperparathyroidism and its associated abnormalities in mineral metabolism and haemodynamic changes increase the cardiovascular risk in patients with end-stage renal disease (ESRD). Our objective was to determine the association of parathyroidectomy (PTX) with major cardiovascular events in nondiabetic dialysis patients with severe secondary hyperparathyroidism (SHPTH).

DESIGN AND PATIENTS

We performed a cohort study with fifty-three nondiabetic ESRD patients who were treated with maintenance haemodialysis and who had intact parathyroid hormone (PTH) levels > 800 pg/ml. Participants received either only medical therapy or medical therapy and total PTX with autotransplantation for SHPTH.

MEASUREMENTS

We evaluated the associations between PTX and major cardiovascular events including death, cerebrovascular accident and myocardial infarction. The biochemical and haemodynamic changes associated with PTX were measured.

RESULTS

During the mean follow-up of 72 months, twenty-three patients received only medical treatment (medical group) while thirty patients underwent PTX in addition to medical treatment (PTX group). The two groups were comparable in respect of baseline characteristics. PTX group was found to be associated with a reduced incidence of major cardiovascular events (P = 0·021). A multiple Cox regression analysis showed that the variable significantly associated with major cardiovascular events was treatment modality (medical therapy vs medical therapy and parathyroidectomy, hazard ratio = 26·12, 95% CI = 1·30-526·27, P = 0·033). Blood pressure, haemoglobin, alkaline phosphatase, calcium, phosphate and calcium × phosphate product significantly improved after PTX.

CONCLUSIONS

PTX was associated with better cardiovascular outcome in nondiabetic dialysis patients with severe SHPTH.

Fragility fractures and osteoporosis in CKD: pathophysiology and diagnostic methods

Both chronic kidney disease (CKD) and osteoporosis are major public health problems associated with an aging population. Osteoporosis is characterized by reduced bone mineral density, while CKD results in qualitative changes in bone structure; both conditions increase the predisposition to fragility fractures. There is a significant coprevalence of osteoporotic fractures and CKD, particularly in the elderly population. Not only is the risk of fracture higher in the CKD population, but clinical outcomes are significantly worse, with substantial health care costs. Management of osteoporosis in the CKD population is particularly complex given the impact of renal osteodystrophy on bone quality and the limited safety and hard outcome data for current therapy in patients with severe CKD or on dialysis therapy. In this review, we discuss the pathophysiology of osteoporosis, the impact of CKD on bone strength, and the role of novel imaging techniques and biomarkers in predicting underlying renal osteodystrophy on bone histomorphometry in the context of CKD.

Balancing nutrition and serum phosphorus in maintenance dialysis

Elevated serum phosphorus levels are common in patients with chronic kidney disease and are associated with heart and vascular disease, conditions that in turn are associated with increased mortality. Accurately managing phosphorus intake by restricting dietary protein alone can prove challenging because protein from different sources can contain varying amounts of available phosphorus. Additives used in processed foods frequently are high in inorganic phosphorus, which is readily absorbed, compounding this difficulty. Recent evidence suggests that dietary protein restriction in some cases may do more harm than good in some patients treated with maintenance hemodialysis because protein restriction can lead to protein-energy wasting, which is associated with increased mortality. Accordingly, phosphorus binders are important for managing hyperphosphatemia in dialysis patients. Managing hyperphosphatemia in patients with late-stage chronic kidney disease requires an individualized approach, involving a combination of adequate dietary advice, phosphate-binder use, and adjustments to dialysis prescription. We speculate that increased use of phosphate binders could allow patients to eat more protein-rich foods and that communicating this to patients might increase their perception of their need for phosphate binders, providing an incentive to improve adherence. The aim of this review is to discuss the challenges involved in maintaining adequate nutrition while controlling phosphorus levels in patients on maintenance hemodialysis therapy.

The EVOLVE study is negative, so what does this 'bitter pill' of disappointment mean now for renal patients?

The extremely high morbidity and mortality experienced by subjects with chronic kidney disease (CKD) has often been described and reviewed, but this familiarity should not breed indifference to the huge burden of premature cardiovascular disease – something which becomes more obvious, but increasingly challenging to treat, as GFR declines, or proteinuria increases. The health outcomes for a middle-aged person entering renal replacement therapy are as bad as those seen with a major solid organ malignancy; while there has been modest progress in improving outcomes over the last two decades, the diagnosis of significant or progressive CKD should and thus still does continue to cast a shadow over patients, carers and healthcare professionals alike.

Laboratory abnormalities in CKD-MBD: markers, predictors, or mediators of disease?

Chronic kidney disease-mineral and bone disorder (CKD-MBD) is characterized by bone abnormalities, vascular calcification, and an array of laboratory abnormalities. The latter classically include disturbances in the parathyroid hormone/vitamin D axis. More recently, fibroblast growth factor 23 (FGF23) and klotho also have been identified as important regulators of mineral metabolism. Klotho deficiency and high circulating FGF23 levels precede secondary hyperparathyroidism in CKD patients. Levels of FGF23 and parathyroid hormone increase along the progression of CKD to maintain mineral homeostasis and to overcome end-organ resistance. It is hard to define when the increase of both hormones becomes maladaptive. CKD-MBD is associated with adverse outcomes including cardiovascular disease and mortality. This review summarizes the complex pathophysiology of CKD-MBD and outlines which laboratory abnormalities represent biomarkers of disease severity, which laboratory abnormalities are predictors of cardiovascular disease, and which laboratory abnormalities should be considered (direct) uremic toxins exerting organ damage. This information may help to streamline current and future therapeutic efforts.

[Mineral and bone disorder in chronic kidney disease : Critical appraisal of pharmacotherapy]

BACKGROUND

Mineral and bone disorder (MBD) in chronic kidney disease (CKD) is associated with increased cardiovascular calcification and mortality. Pharmacological interventions for MBD in CKD are characterized by inconsistent data and a wide spectrum of (sometimes costly) treatment options. The objective of this article is a guideline-oriented overview of the differential indications for pharmacotherapy considering cost-effectiveness.

CURRENT DATA

The serum phosphate concentration in patients with CKD stages 3-5 with a glomerular filtration rate (GFR) of < 45 ml/min should be kept within the normal range. Currently, under consideration of cost-effectiveness, calcium-containing phosphate binders and combinations of calcium acetate with magnesium carbonate are the preferred treatment options. Phosphate binders free of calcium are indicated in patients with high normal or elevated serum calcium levels. Low vitamin D concentrations in CKD stages 3-5 should be treated under consideration of serum calcium and parathyroid hormone (PTH) with calcidiol (25-cholecalciferol) and in dialysis patients (CKD 5D) with calcitriol (1,25 dihydroxycholecalciferol, activated vitamin D). In CKD the PTH levels should be kept in the range of 2-9-times the upper limit of normal levels. This is achieved by administration of phosphate binding drugs, activated vitamin D, calcimimetic compounds and parathyroidectomy. In CKD stages 3-5 patients metabolic acidosis with < 22 mmol/l serum bicarbonate should be treated with oral sodium bicarbonate.

CONCLUSION

In MBD of CKD patients an individualized pharmacotherapy which is closely guideline-oriented is required in order to achieve cost-effectiveness.