Phosphate binder use and mortality among hemodialysis patients in the Dialysis Outcomes and Practice Patterns Study (DOPPS): evaluation of possible confounding by nutritional status

Phosphate binder pill burden and cardiovascular events in patients undergoing hemodialysis

BACKGROUND

Phosphate binders (PBs) are commonly prescribed to reduce serum phosphate levels. This study examined the association between the PB pill burden and cardiovascular events in hemodialysis patients.

METHODS

This retrospective cohort study included 395 patients undergoing hemodialysis between August 2018 and November 2023 at a single facility in Japan. Statistical analyses were conducted using baseline, time-averaged, and time-dependent Cox proportional hazard models.

RESULTS

Of the 395 included patients, cardiovascular events occurred in 121 patients (30.6%). The patients were categorized into tertiles based on their daily PB pill intake: T1 (<4 pills/day), T2 (4-8 pills/day), and T3 (≥9 pills/day). T3 was associated with increased cardiovascular risk (vs. T1 hazard ratio [HR] = 1.51, p = 0.064; vs. T2 HR = 2.06, p = 0.005). Similar results were obtained for the time-averaged and time-dependent models.

CONCLUSION

A high PB pill burden (≥9/day) is associated with increased cardiovascular risk in patients undergoing hemodialysis.

Association of Ankle-Brachial Index with Quality of Life and Survival Outcomes in Hemodialysis Patients

Background/Objectives: Ankle-brachial index (ABI) is frequently measured in hemodialysis patients due to their high cardiovascular risk, while its potential role as a screening tool for assessing overall physical function and health-related quality of life (QOL) remains unclear. This study aimed to evaluate the association of the ABI with QOL and survival in hemodialysis patients. Methods: This study included 346 hemodialysis patients, categorized into two groups based on their ABI (≤0.9 vs. >0.9). Clinical parameters, QOL (measured using SF-36 and KDQOL questionnaires), and survival outcomes were analyzed. Results: There were 66 (19.1%) patients with an ABI ≤ 0.9 in this study population. Patients with an ABI ≤ 0.9 exhibited significantly older ages, longer dialysis durations, higher prevalence of diabetes mellites and cardiovascular disease, elevated N-terminal pro-brain natriuretic peptide levels, and higher calcitriol use but lower phase angle, skeletal muscle mass index values, health-related QOL domains, and several kidney disease-specific QOL domains compared to those with an ABI > 0.9. Kaplan-Meier analysis revealed significantly higher cumulative mortality in the ABI ≤ 0.9 group (6.6 vs. 2.5 per 100 patient-years, p < 0.001). Conclusions: A low ABI is significantly associated with decreased QOL and higher mortality risk in hemodialysis patients. While traditionally used for PAD screening, the ABI may serve as a practical tool for predicting QOL decline and survival outcomes. Interestingly, the ABI was also linked to muscle attenuation and volume overload. ABI assessment could aid in early risk stratification and guide multidisciplinary interventions, including exercise programs, nutritional support, and cardiovascular risk management, to improve patient care and outcomes.

The Bone-Vascular Axis in Chronic Kidney Disease: From Pathophysiology to Treatment

PURPOSE OF REVIEW

This review aims to describe the pathogenic factors involved in bone-vessel anomalies in CKD which are the object of numerous experimental and clinical research.

RECENT FINDINGS

Knowledge on the pathophysiological mechanisms involved in the regulation of vascular calcification and mineral-bone disorders is evolving. Specific bone turnover anomalies influence the vascular health while recent studies demonstrate that factors released by the calcified vessels also contribute to bone deterioration in CKD. Current therapies used to control mineral dysregulations will impact both the vessels and bone metabolism. Available anti-osteoporotic treatments used in non-CKD population may negatively or positively affect vascular health in the context of CKD. It is essential to study the bone effects of the new therapeutic options that are currently under investigation to reduce vascular calcification. Our paper highlights the complexity of the bone-vascular axis and discusses how current therapies may affect both organs in CKD.

Association between phosphate binder pill burden and mortality risk in patients on maintenance hemodialysis: a single-center cohort study with 7-year follow-up of 513 patients

BACKGROUND

Dialysis patients often take multiple oral medications, leading to a high pill burden. Phosphate binders (PBs) account for a large proportion of this daily pill burden (DPB). The relationship between DPB and mortality risk remains unclear, and we hypothesized that this relationship might be influenced by the proportion of PBs to all medications.

METHODS

We divided DPB into those derived from PBs and non-PB drugs and analyzed the association with mortality risk over a 7-year period in 513 chronic hemodialysis patients using a baseline model.

RESULTS

The median (interquartile range) DPB from all drugs was 15.8 (11.2-21.0) pills/day/patient, and the median ratio of PB pills to all drug pills was 29.3 (13.7-45.9)% at baseline. During a median observation period of 5.2 years, 161 patients (31.4%) died. Kaplan-Meier analysis showed no significant difference in all-cause mortality between PB users and non-users. However, a significant survival advantage was observed in the highest tertile of DPB from PBs compared to the lowest tertile. Conversely, the highest tertile of DPB from non-PB drugs was associated with worse survival. Consequently, the highest tertile of the ratio of PBs to all pills was associated with better survival. This association remained significant even after adjusting for patient characteristics in the Cox proportional hazards model. However, when serum nutritional parameters were included as covariates, the significant association disappeared.

CONCLUSIONS

Dialysis patients prescribed a higher rate of PB pills to all medications exhibited a lower mortality risk, possibly due to their better nutritional status.

Validation of a Phosphorus Food Frequency Questionnaire in Patients with Kidney Failure Undertaking Dialysis

Nutritional guidelines recommended limiting dietary phosphorus as part of phosphorus management in patients with kidney failure. Currently, there is no validated phosphorus food frequency questionnaire (P-FFQ) to easily capture this nutrient intake. An FFQ of this type would facilitate efficient screening of dietary sources of phosphorus and assist in developing a patient-centered treatment plan. The objectives of this study were to develop and validate a P-FFQ by comparing it with the 24 hr multi-pass recall. Fifty participants (66% male, age 70 ± 13.3 years) with kidney failure undertaking dialysis were recruited from hospital nephrology outpatient departments. All participants completed the P-FFQ and 24 hr multi-pass recalls with assistance from a renal dietitian and then analysed using nutrient analysis software. Bland-Altman analyses were used to determine the agreement between P-FFQ and mean phosphorus intake from three 24 hr multi-pass recalls. Mean phosphorous intake was 1262 ± 400 mg as determined by the 24 hr multi pass recalls and 1220 ± 348 mg as determined by the P-FFQ. There was a moderate correlation between the P-FFQ and 24 hr multi pass recall (r = 0.62, p = 0.37) with a mean difference of 42 mg (95% limits of agreement: 685 mg; -601 mg, p = 0.373) between the two methods. The precision of the P-FFQ was 3.33%, indicating suitability as an alternative to the 24 hr multi pass recall technique. These findings indicate that the P-FFQ is a valid, accurate, and precise tool for assessing sources of dietary phosphorus in people with kidney failure undertaking dialysis and could be used as a tool to help identify potentially problematic areas of dietary intake in those who may have a high serum phosphate.

Real-World Phosphate Binder Use among Dialysis-Dependent Patients with CKD

INTRODUCTION

For patients with chronic kidney disease (CKD), the need for phosphate binder (PB) treatment peaks at onset of dialysis. This real-world study assessed rates of PB utilization and switching in patients with dialysis-dependent CKD (DD-CKD).

METHODS

We identified patients with PB utilization among those with prevalent DD-CKD using 2018-2019 Medicare Parts A/B/D data. Patients were assigned to cohorts based on primary (most frequently used) PB among calcium acetate, ferric citrate, lanthanum carbonate, sevelamer (hydrochloride and carbonate), sucroferric oxyhydroxide. We measured proportion of patients who were adherent (proportion of days covered >80%) and persistent (patients whose last 90 days of outpatient dialysis reported PB use). Net switching rates were calculated as the difference between switches to and from the primary agent.

RESULTS

We identified 136,912 patients with PB use. Proportion of patients adherent ranged from 63.8% (lanthanum carbonate) to 67.7% (sevelamer) and persistent from 85.1% (calcium acetate) to 89.5% (ferric citrate). Most patients (73%) used the same PB throughout the study. Overall, 20.5% of patients experienced one switch and 2.3% two or more. Positive net switching rates were observed for ferric citrate, sucroferric oxyhydroxide, and lanthanum carbonate (2-10%) but negative for sevelamer and calcium acetate (-2% to -7%).

CONCLUSION

Adherence and persistence rates were low with slight variation across PBs. Net positive switching occurred for ferric citrate, sucroferric oxyhydroxide, and lanthanum carbonate. Further studies are needed to determine the reasons for these findings and could identify opportunities for better control of phosphate levels among patients with CKD.

A real-world analysis of the influence of age on maintenance hemodialysis patients: managing serum phosphorus with sucroferric oxyhydroxide as part of routine clinical care

OBJECTIVE

Despite the growing number of elderly hemodialysis patients, the influence of age on nutritional parameters, serum phosphorus (sP), and use of phosphate-binder (PB) medications has not been well characterized. We aimed to describe age-related differences in patient characteristics in a large, real-world cohort of maintenance hemodialysis patients, and to examine the impact of age on sP management with sucroferric oxyhydroxide (SO).

METHODS

We retrospectively analyzed de-identified data from 2017 adult, in-center hemodialysis patients who switched from another PB to SO monotherapy as part of routine clinical care. Changes in baseline PB pill burden, sP levels, and nutritional and dialytic clearance parameters were assessed across varying age groups through 6 months.

RESULTS

At baseline, older patients had lower mean sP, serum albumin, and pre-dialysis weights compared with younger patients. Prescription of SO was associated with a 62% increase in the proportion of patients achieving sP ≤ 5.5 mg/dl and a 42% reduction in daily pill burden. The proportion of patients achieving sP ≤ 5.5 mg/dl after transitioning to SO increased by 113, 96, 68, 77, 61, 37 and 40% among those aged 19-29, 30-39, 40-49, 50-59, 60-69, 70-79, and ≥ 80 years, respectively.

CONCLUSIONS

Older patients had worse nutritional parameters, lower pill burden, and lower sP at baseline versus younger counterparts. Prescription of SO was associated with improved sP control and reduced pill burden across all ages.

High phosphate-induced progressive proximal tubular injury is associated with the activation of Stat3/Kim-1 signaling pathway and macrophage recruitment

Dietary phosphate intake in the Western population greatly exceeds the recommended dietary allowance and is linked to enhanced cardiovascular and all-cause mortality. It is unclear whether a chronic high phosphate diet (HPD) causes kidney injury in healthy individuals. Here, we show that feeding a 2% HPD in C57BL/6N mice for one up to six months resulted in hyperphosphatemia, hyperphosphaturia, increased plasma levels of fibroblast growth factor (FGF) 23, and parathyroid hormone (PTH) compared to mice on a 0.8% phosphate diet. Kidney injury was already noted after two months of HPD characterized by loss of proximal tubular (PT) cell polarity, flattened epithelia, disruption of brush border membranes, vacuolization, increased PT cell proliferation, marked interstitial mononuclear infiltration, and progressive accumulation of collagen fibers. HPD increased Stat3 activation and Kim-1 expression in PT epithelial cells and enhanced renal synthesis of chemokines recruiting monocytes and macrophages as well as macrophage related factors. Enhanced recruitment of F4/80⁺ macrophages around injured PT lesions was timely associated with increased Kim-1 synthesis, tubular MCP-1 expression, and degree of PT injury score. Likewise, tubulointerstitial fibrosis was associated with activation of Stat3/Kim-1 signaling pathway. The stimulation of human proximal tubular cells with high phosphate activated Stat3 signaling and induced HAVCR1 and CCL2 expression. We conclude that high phosphate results in progressive proximal tubular injury, indicating that high dietary phosphate intake may affect kidney health and therefore represents an underestimated health problem for the general population.

Non calcium phosphate binders - Is there any evidence of benefit

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Impact of phosphate binders on medication dosing frequency, timing, and number of prescribed pills in hemodialysis patients

INTRODUCTION

Phosphate binders (PBs) account for a large proportion of the daily pill burden in hemodialysis patients. However, patients do not take them all at once but at several dosing timings.

METHODS

We analyzed the dosing timings of all 322 types of oral drugs prescribed to 533 hemodialysis patients.

RESULTS

The median daily dosing frequency for all drugs was 6 (4-7) times/day/patient. Patients prescribed PBs had a markedly higher daily dosing frequency than those not taking PBs [7 (5-8) times /day/patient versus 4 (3-5) times/day/patient, respectively (P<0.001)]. In addition, the ratio of the number of PB pills to other drugs varied greatly at each dosing timing. Furthermore, it was simulated that the daily dosing frequency could be reduced by approximately two times/day/patient by combining the dosing timings of PBs.

CONCLUSION

Changing PB dosing timings can reduce the daily dosing frequency, which may lead to improved medication adherence.

Sucroferric oxyhydroxide for hyperphosphatemia: a review of real-world evidence

Hyperphosphatemia is a common complication in dialysis-dependent patients with chronic kidney disease. Most dialysis-dependent patients need oral phosphate binder therapy to control serum phosphorus concentrations. Most phosphate binders have a high daily pill burden, which may reduce treatment adherence and impair phosphorus control. Sucroferric oxyhydroxide is a potent iron-based phosphate binder approved for use in dialysis-dependent patients in 2013. A randomized controlled trial of sucroferric oxyhydroxide demonstrated its efficacy for reduction of serum phosphorus with a lower pill burden than sevelamer carbonate. Clinical trials carefully select patients, monitor adherence, and routinely titrate medications to a protocol-defined goal. Consequently, trials may not reflect real-world use of medications. Since its approval, we and others have performed retrospective and prospective analyses of sucroferric oxyhydroxide in real-world clinical practice in > 6400 hemodialysis and approximately 500 peritoneal dialysis patients in the USA and Europe. Consistent with the clinical trial data, real-world observational studies have demonstrated that sucroferric oxyhydroxide can effectively reduce serum phosphorus with a lower daily pill burden than most other phosphate binders. These studies have also shown sucroferric oxyhydroxide provides effective serum phosphorus control in different treatment settings, including as monotherapy in phosphate binder-naïve patients, in patients switching from other phosphate binders, or when used in combination with other phosphate binders. These observational studies indicate a favorable safety and tolerability profile, and minimal, if any, systemic iron absorption. This article reviews the key results from these observational studies of sucroferric oxyhydroxide and evaluates its role in the management of hyperphosphatemia in clinical practice.

Systematic Review and Meta-Analyses of the Effects of Phosphate-Lowering Agents in Nondialysis CKD

BACKGROUND

Benefits of phosphate-lowering interventions on clinical outcomes in patients with CKD are unclear; systematic reviews have predominantly involved patients on dialysis. This study aimed to summarize evidence from randomized controlled trials (RCTs) concerning benefits and risks of noncalcium-based phosphate-lowering treatment in nondialysis CKD.

METHODS

We conducted a systematic review and meta-analyses of RCTs involving noncalcium-based phosphate-lowering therapy compared with placebo, calcium-based binders, or no study medication, in adults with CKD not on dialysis or post-transplant. RCTs had ≥3 months follow-up and outcomes included biomarkers of mineral metabolism, cardiovascular parameters, and adverse events. Outcomes were meta-analyzed using the Sidik-Jonkman method for random effects. Unstandardized mean differences were used as effect sizes for continuous outcomes with common measurement units and Hedge's g standardized mean differences (SMD) otherwise. Odds ratios were used for binary outcomes. Cochrane risk of bias and GRADE assessment determined the certainty of evidence.

RESULTS

In total, 20 trials involving 2498 participants (median sample size 120, median follow-up 9 months) were eligible for inclusion. Overall, risk of bias was low. Compared with placebo, noncalcium-based phosphate binders reduced serum phosphate (12 trials, weighted mean difference -0.37; 95% CI, -0.58 to -0.15 mg/dl, low certainty evidence) and urinary phosphate excretion (eight trials, SMD -0.61; 95% CI, -0.90 to -0.31, low certainty evidence), but resulted in increased constipation (nine trials, log odds ratio [OR] 0.93; 95% CI, 0.02 to 1.83, low certainty evidence) and greater vascular calcification score (three trials, SMD, 0.47; 95% CI, 0.17 to 0.77, very low certainty evidence). Data for effects of phosphate-lowering therapy on cardiovascular events (log OR, 0.51; 95% CI, -0.51 to 1.17) and death were scant.

CONCLUSIONS

Noncalcium-based phosphate-lowering therapy reduced serum phosphate and urinary phosphate excretion, but there was an unclear effect on clinical outcomes and intermediate cardiovascular end points. Adequately powered RCTs are required to evaluate benefits and risks of phosphate-lowering therapy on patient-centered outcomes.

Tailored synbiotic powder (functional food) to prevent hyperphosphataemia (kidney disorder)

Hyperphosphataemia is treated with phosphate binders, which can cause adverse effects. Spray-dried synbiotic powder (SP) composed of Lactobacillus casei JCM1134 (a phosphate-accumulating organism; PAO) and Aloe vera is potentially a safer alternative for efficient phosphate removal. In this study, a novel strategy was developed; lysine-derivatized deacetylated A. vera (DAVK) was synthesised and fabricated on phosphate-deficient PAO (PDP) for efficient phosphate transfer and then spray-dried with the supernatant of DAV centrifugation to form a sacrificial layer on PDP for SP integrity during gastric passage. In vitro experiments revealed that PAO removed only 1.6% of the phosphate from synthetic media, whereas SP removed 89%, 87%, and 67% (w/v) of the phosphate from milk, soft drink, and synthetic media, respectively, confirming the protective role of A. vera and efficient phosphate transport. Compared with commercial binders, SP effectively removed phosphate from synthetic media, whereas SP and CaCO3 exhibited comparative results for milk and soft drink. Importantly, CaCO3 caused hypercalcaemia. Thus, the described SP presents a promising tool to prevent hyperphosphataemia. This study also revealed a novel factor: diets of patients with chronic kidney disease should be monitored to determine the optimal phosphate binders, as phosphate removal performance depends on the accessible phosphate forms.

Phosphate Balance and CKD-Mineral Bone Disease

Chronic kidney disease-mineral bone disorder (CKD-MBD) is a common comorbidity in patients with CKD. Characterized by laboratory abnormalities, bone abnormality, and vascular calcification, CKD-MBD encompasses a group of mineral and hormone disturbances that are strongly associated with increased cardiovascular (CV) morbidity and mortality. Abnormal serum phosphate concentrations are an independent risk factor for CV morbidity and mortality, and overall mortality. Phosphate retention plays a central role in initiating and driving many other disturbances in CKD-MBD (e.g., increased parathyroid hormone and fibroblast growth factor 23 concentrations, hypocalcemia, low vitamin D) that are also linked to increased CV risk. Thus, effective phosphate control is a logical therapeutic target for CKD-MBD treatment. Current phosphate management strategies (dietary restrictions, dialysis, phosphate binders) are insufficient to consistently achieve and maintain target phosphate concentrations in patients on dialysis. Phosphate binders reduce available phosphate for intestinal absorption but do not impair the dominant phosphate absorption pathway. Novel therapies that consider new mechanistic understandings of intestinal phosphate absorption are needed. One such therapy is tenapanor, a targeted sodium-hydrogen exchanger isoform 3 inhibitor that has been shown to reduce serum phosphate concentrations in multiple clinical trials. Tenapanor has a novel mechanism of action that reduces intestinal phosphate absorption in the primary paracellular phosphate absorption pathway.

Long-term efficacy and safety of iron-based phosphate binders, ferric citrate hydrate and sucroferric oxyhydroxide, in hemodialysis patients

PURPOSE

Iron-based phosphate binders, including ferric citrate hydrate (FCH) and sucroferric oxyhydroxide (SFOH), have been used for the treatment of hyperphosphatemia in end-stage renal disease patients on dialysis. However, the long-term efficacy and safety of these agents have not yet been clearly elucidated.

METHODS

Laboratory data of 56 hemodialysis patients who had been prescribed either FCH (n = 33) or SFOH (n = 23) were retrospectively examined.

RESULTS

We showed that both FCH and SFOH significantly and consistently decreased serum phosphate concentrations in the patients undergoing maintenance hemodialysis during the 36-month observation period. Serum levels of calcium, intact parathyroid hormone, as well as hemoglobin levels were unaltered. No overshoot of parameters of iron metabolism, such as transferrin saturation and serum ferritin levels, was observed, and serum ferritin level remained under 300 ng/mL in most patients. A trend towards decrease in the doses of erythropoiesis-stimulating agents used and frequency of intravenous iron use was observed in both treatment groups. No severe adverse drug reactions were observed in either the patients receiving FCH or SFOH.

CONCLUSION

The results of the present study suggest that the iron-based phosphate binders, FCH and SFOH, decrease serum phosphate concentrations consistently and are safe to use over the long-term in maintenance hemodialysis patients.

European hemodialysis patient satisfaction with phosphate binders is associated with serum phosphorus levels: the Dialysis Outcomes and Practice Patterns Study

Background

Hemodialysis (HD) patients are commonly prescribed phosphate binders (PBs) to manage serum phosphorus levels, as hyperphosphatemia is strongly associated with poorer survival. Nonadherence with the PB prescription is associated with elevated serum phosphorus levels. We studied associations between patient satisfaction with their PB and serum phosphorus levels and mortality rates.

Methods

Adult HD patients in Germany, Italy, Spain and the UK in the Dialysis Outcomes and Practice Patterns Study were administered a survey instrument in late 2017. Patients were asked about their satisfaction with their PBs, as measured through three questions (difficulty, inconvenience and dissatisfaction) on a 5-point Likert scale, with each dichotomized into average worst versus good responses. These were used as predictors in linear regression models of continuous serum phosphorus levels and in Cox proportional hazards models of mortality, with adjustments for demographics, comorbidities and laboratory values.

Results

Patients having greater difficulty, inconvenience and dissatisfaction with their PB had higher serum phosphorus levels in adjusted models {+0.21 mg/dL [95% confidence interval (CI) ±0.23], +0.30 (±0.21) and 0.36 (±0.22), respectively}, and higher odds of having serum phosphorus levels ≥6.0 mg/dL. Measures of dissatisfaction were also associated with an elevated risk of mortality, with adjusted hazard ratios of 2.2 (95% CI 1.3–3.6), 1.6 (1.0–2.6) and 1.7 (1.1–2.7), respectively; this association was not strongly affected by adjustment for baseline serum phosphorous level.

Conclusions

Self-reported difficulty, inconvenience and dissatisfaction in taking one’s prescribed PBs were associated with elevated serum phosphorus levels and serum phosphorus levels above clinically meaningful thresholds. While the mechanism for the association with mortality is unclear, patient-reported satisfaction should be considered when attempting to manage patient serum phosphorus levels.

Design and Rationale of HiLo: A Pragmatic, Randomized Trial of Phosphate Management for Patients Receiving Maintenance Hemodialysis

RATIONALE & OBJECTIVE

Hyperphosphatemia is a risk factor for poor clinical outcomes in patients with kidney failure receiving maintenance dialysis. Opinion-based clinical practice guidelines recommend the use of phosphate binders and dietary phosphate restriction to lower serum phosphate levels toward the normal range in patients receiving maintenance dialysis, but the benefits of these approaches and the optimal serum phosphate target have not been tested in randomized trials. It is also unknown if aggressive treatment that achieves unnecessarily low serum phosphate levels worsens outcomes.

STUDY DESIGN

Multicenter, pragmatic, cluster-randomized clinical trial.

SETTING & PARTICIPANTS

HiLo will randomize 80-120 dialysis facilities operated by DaVita Inc and the University of Utah to enroll 4,400 patients undergoing 3-times-weekly, in-center hemodialysis.

INTERVENTION

Phosphate binder prescriptions and dietary recommendations to achieve the "Hi" serum phosphate target (≥6.5 mg/dL) or the "Lo" serum phosphate target (<5.5 mg/dL).

OUTCOMES

Primary outcome: Hierarchical composite outcome of all-cause mortality and all-cause hospitalization. Main secondary outcomes: Individual components of the primary outcome.

RESULTS

The trial is currently enrolling.

LIMITATIONS

HiLo will not adjudicate causes of hospitalizations or mortality and does not protocolize use of specific phosphate binder classes.

CONCLUSIONS

HiLo aims to address an important clinical question while more generally advancing methods for pragmatic clinical trials in nephrology by introducing multiple innovative features including stakeholder engagement in the study design, liberal eligibility criteria, use of electronic informed consent, engagement of dietitians to implement the interventions in real-world practice, leveraging electronic health records to eliminate dedicated study visits, remote monitoring of serum phosphate separation between trial arms, and use of a novel hierarchical composite outcome.

TRIAL REGISTRATION

Registered at ClinicalTrials.gov with study number NCT04095039.

Phosphate and bone fracture risk in chronic kidney disease patients

In chronic kidney disease (CKD), phosphate homoeostasis plays a central role in the development of mineral and bone disorder (MBD) together with decreased serum calcium and elevated serum parathyroid hormone, fibroblast growth factor 23 and sclerostin levels. Today there are only a few data exploring the direct role of abnormal phosphate homoeostasis and hyperphosphataemia in the development of CKD-MBD. On the other hand, several studies have looked at the link between hyperphosphataemia and cardiovascular morbidity and mortality in CKD, but there is a lack of evidence to indicate that lowering phosphate levels improves cardiovascular outcomes in this population. Furthermore, the impact of liberalizing phosphate targets on CKD-MBD progression and bone fracture is currently not known. In this review we discuss the central role of phosphate in the pathogenesis of CKD-MBD and how it may be associated with fracture risk, both in hyper- and hypophosphataemia.

The Importance of Phosphate Control in Chronic Kidney Disease

A series of problems including osteopathy, abnormal serum data, and vascular calcification associated with chronic kidney disease (CKD) are now collectively called CKD-mineral bone disease (CKD-MBD). The pathophysiology of CKD-MBD is becoming clear with the emerging of αKlotho, originally identified as a progeria-causing protein, and bone-derived phosphaturic fibroblast growth factor 23 (FGF23) as associated factors. Meanwhile, compared with calcium and parathyroid hormone, which have long been linked with CKD-MBD, phosphate is now attracting more attention because of its association with complications and outcomes. Incidentally, as the pivotal roles of FGF23 and αKlotho in phosphate metabolism have been unveiled, how phosphate metabolism and hyperphosphatemia are involved in CKD-MBD and how they can be clinically treated have become of great interest. Thus, the aim of this review is reconsider CKD-MBD from the viewpoint of phosphorus, its involvement in the pathophysiology, causing complications, therapeutic approach based on the clinical evidence, and clarifying the importance of phosphorus management.

Optimal Phosphate Control Related to Coronary Artery Calcification in Dialysis Patients

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

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

Cardiovascular mortality in peritoneal dialysis: the impact of mineral disorders

Introduction:

Mineral and bone disorders (MBD) are associated with higher mortality in dialysis patients. The main guidelines related to the subject, Kidney Disease Outcomes Quality Initiative (KDOQI) and Kidney Disease: Improving Global Outcomes (KDIGO), were elaborated based on published information from hemodialysis participants. The aim of our study was to evaluate the impact of calcium (Ca), phosphorus (P), and parathyroid hormone (PTH) (according to guideline ranges from KDOQI and KDIGO) on the cardiovascular mortality of peritoneal dialysis (PD) patients.

Methods:

We used the BRAZPDII database, an observational multi-centric prospective study, which assessed participants on PD between December 2004 and January 2011. Amongst 9,905 participants included in this database, we analyzed 4424 participants who were on PD for at least 6 months. The appropriate confounding variables were entered into the model. Serum levels of Ca, P, and PTH were the variables of interest for the purposes of the current study.

Results:

We found a significant association between high P serum levels, categorized by KDOQI and KDIGO (P above 5.5 mg/dL), and cardiovascular survival (p < 0.01). Likewise, a compelling association was found between lower levels of PTH, categorized by guidelines (KDOQI and KDIGO - PTH less than 150 pg/mL, p < 0.01), and cardiovascular survival.

Conclusion:

In conclusion, levels of P above and PTH below the values proposed by KDOQI and KDIGO were associated with cardiovascular mortality in PD patients.

Prescription characteristics of phosphate binders in a high pill burden for hemodialysis patients

Background

Dialysis patients have to take many oral drugs, causing a high pill burden. Phosphate binders (PBs) account for a large proportion of daily pill burden; however, the relationship between patient background and prescription status of PBs is not clear.

Methods

We clarified the characteristics of PBs in the total daily pill burden by analyzing the drugs prescribed for 533 chronic hemodialysis patients in our facility.

Results

An average of nine different types of oral drugs was prescribed for each patient. The mean and median values of total pill burden were 15.1 and 14.1 pills/day/patient, respectively. The total pill burden showed a significant negative correlation with age and a significant positive correlation with dialysis vintage. In addition, the total pill burden was significantly higher in males than in females. However, there was no difference in the pill burden between patients with and without diabetes mellitus (DM). PBs were prescribed to 409 patients (76.7%), and the mean pill burden derived from PBs was 6.44 pills/day/patient. This was by far the highest of all 35 different drug categories and accounted for 32.84% of all pills. Multiple regression analysis demonstrated that independent predictors of total pill burden were age, dialysis vintage, DM, and serum phosphorus (P) levels, and all these variables, except DM, were also independent predictors of pill burden from PBs. These variables were also selected when considering the use of calcimimetics.

Conclusions

A high pill burden is more likely to occur in younger patients with longer dialysis vintage, DM, higher serum P levels, and prescription of calcimimetics. In addition, PB was the single largest contributor to the total pill burden that positively and linearly linked to serum P levels. Therefore, P management is a high-priority issue in the mitigation of high pill burdens in dialysis patients.

Impact of longer term phosphorus control on cardiovascular mortality in hemodialysis patients using an area under the curve approach: results from the DOPPS

BACKGROUND

Serial assessment of phosphorus is currently recommended by the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines, but its additional value versus a single measurement is uncertain.

METHODS

We studied data from 17 414 HD patients in the Dialysis Outcomes and Practice Patterns Study, a prospective cohort study, and calculated the area under the curve (AUC) by multiplying the time spent with serum phosphorus >4.5 mg/dL over a 6-month run-in period by the extent to which this threshold was exceeded. We estimated the association between the monthly average AUC and cardiovascular (CV) mortality using Cox regression. We formally assessed whether AUC was a better predictor of CV mortality than other measures of phosphorus control according to the Akaike information criterion.

RESULTS

Compared with the reference group of AUC = 0, the adjusted hazard ratio (HR) of CV mortality was 1.12 [95% confidence interval (CI) 0.90-1.40] for AUC > 0-0.5, 1.26 (95% CI 0.99-1.62) for AUC > 0.5-1, 1.44 (95% CI 1.11-1.86) for AUC > 1-2 and 2.03 (95% CI 1.53-2.69) for AUC > 2. The AUC was predictive of CV mortality within strata of the most recent phosphorus level and had a better model fit than other serial measures of phosphorus control (mean phosphorus, months out of target).

CONCLUSIONS

We conclude that worse phosphorus control over a 6-month period was strongly associated with CV mortality. The more phosphorus values do not exceed 4.5 mg/dL the better is survival. Phosphorus AUC is a better predictor of CV death than the single most recent phosphorus level, supporting with real-world data KDIGO's recommendation of serial assessment of phosphorus to guide clinical decisions.

The Causes of Hypo- and Hyperphosphatemia in Humans

Phosphate homeostasis involves several major organs that are the skeleton, the intestine, the kidney, and parathyroid glands. Major regulators of phosphate homeostasis are parathormone, fibroblast growth factor 23, 1,25-dihydroxyvitamin D, which respond to variations of serum phosphate levels and act to increase or decrease intestinal absorption and renal tubular reabsorption, through the modulation of expression of transcellular transporters at the intestinal and/or renal tubular level. Any acquired or genetic dysfunction in these major organs or regulators may induce hypo- or hyperphosphatemia. The causes of hypo- and hyperphosphatemia are numerous. This review develops the main causes of acquired and genetic hypo- and hyperphosphatemia.

Survival with low- and high-flux dialysis

Background

Besides advances in haemodialysis (HD), mortality rates are still high. The effect of the different types of HD membranes on survival is still a controversial issue. The aim of this COSMOS (Current management Of Secondary hyperparathyroidism: a Multicentre Observational Study) analysis was to survey, in HD patients, the relationship between the use of conventional low- or high-flux membranes and all-cause and cardiovascular mortality.

Methods

COSMOS is a multicentre, open-cohort, 3-year prospective study, designed to evaluate mineral and bone disorders in the European HD population. The present analysis included 5138 HD patients from 20 European countries, 3502 randomly selected at baseline (68.2%), plus 1636 new patients with <1 year on HD (31.8%) recruited to replace patients who died, were transplanted, switched to peritoneal dialysis or lost to follow-up by other reasons. Cox-regression analysis with time-dependent variables, propensity score matching and the use of an instrumental variable (facility-level analysis) were used.

Results

After adjustments using three different multivariate models, patients treated with high-flux membranes showed a lower all-cause and cardiovascular mortality risks {hazard ratio (HR) = 0.76 [95% confidence interval (CI) 0.61-0.96] and HR = 0.61 (95% CI 0.42-0.87), respectively}, that remained significant after matching by propensity score for all-cause mortality (HR = 0.69, 95% CI 0.52-0.93). However, a facility-level analysis showed no association between the case-mix-adjusted facility percentage of patients dialysed with high-flux membranes and all-cause and cardiovascular mortality.

Conclusions

High-flux dialysis was associated with a lower relative risk of all-cause and cardiovascular mortality. However, dialysis facilities using these dialysis membranes to a greater extent did not show better survival.

Association between modified simple protein-energy wasting (PEW) score and all-cause mortality in patients receiving maintenance hemodialysis

Background

Protein-energy wasting (PEW) is a frequently observed complication that leads to increased mortality in hemodialysis patients. However, a multifaceted assessment of PEW by combined objective nutritional parameters has not yet been established.

Methods

In total, 144 Japanese patients receiving maintenance hemodialysis at a hemodialysis center were retrospectively followed for 7 years. The primary outcome was all-cause death. The main exposure was a modified simple PEW score (0, 1, 2, 3, or 4), calculated from four parameters: serum albumin and creatinine levels, normalized protein catabolic rate, and body mass index. These parameters are included in the subcategories of PEW as defined by the International Society of Renal Nutrition and Management. The cutoff values of the modified simple PEW score components were based on the receiver operating characteristics curves determined by univariate logistic regression analyses. Risk estimates for all-cause mortality were calculated by the Cox proportional hazards model adjusted for potential confounding factors.

Results

During the median 5.7-years follow-up period, 37 patients died of any cause. When patients were divided into three subgroups (G1–G3) based on the modified simple PEW score, a multivariable-adjusted analysis showed that the risks of all-cause death in groups G2 and G3 were significantly higher than in the lowest score group (G1), with hazard risk (95% confidence interval) 3.10 (1.16–8.26) (P = 0.024) and 5.68 (1.85–17.45) (P = 0.002), respectively.

Conclusions

The modified simple PEW score is a useful composite indicator of nutritional status that stratifies the risk of all-cause mortality in patients undergoing maintenance hemodialysis.

Duration of Serum Phosphorus Control Associated with Overall Mortality in Patients Undergoing Peritoneal Dialysis

BACKGROUND

Serum phosphorus (SP) level is closely associated with overall mortality and cardiovascular events, while the role of SP controlled duration is not fully recognized. Here, we conducted a retrospective cohort study in our department to identify the relationship of SP controlled duration with clinical outcomes in patients undergoing peritoneal dialysis (PD).

METHODS

PD patients in our center from January 1, 2009, to June 30, 2019, were followed up at 2-month (the first year) or 5-month (the next follow-up period) intervals, and until death, until PD withdrawal, or until June 30, 2019. Data at each follow-up point were collected from their medical records. SP levels, changed degree of SP over baseline, and SP controlled duration were analyzed with overall mortality, PD withdrawal (including death, transferred to hemodialysis, and received renal transplantation), and combined endpoint (including death, acute heart failure, cardiovascular event, and stroke).

RESULTS

A total of 530 patients entered the analysis. Of them, 456 (86.0%) had hyperphosphatemia before dialysis, and the SP levels decreased soon after dialysis. The degree of SP change over baseline was the maximum at the 3rd month after dialysis (-31.0%), and lower degree was associated with higher overall mortality (hazard ratio [HR], 1.012; 95% CI, 1.004-1.020; p = 0.003). The median SP controlled duration was 13 (5-28) months, and longer duration was significantly associated with lower overall mortality (HR, 0.968; 95% CI, 0.956-0.981; p < 0.001). After categorization, duration more than 12 months greatly improved overall mortality with a HR of 0.197 (0.082-0.458; p < 0.001 vs. SP never controlled group) and 0.329 (0.150-0.724; p = 0.006 vs. duration <12 months group). Longer SP controlled duration also improved PD withdrawal and combined endpoint.

CONCLUSIONS

In summary, both degree and duration of SP control were tightly associated with overall mortality. We should control SP levels as early, as possible, and as long as we could.

EOS789, a broad-spectrum inhibitor of phosphate transport, is safe with an indication of efficacy in a phase 1b randomized crossover trial in hemodialysis patients

The treatment of hyperphosphatemia remains challenging in patients receiving hemodialysis. This phase 1b study assessed safety and efficacy of EOS789, a novel pan-inhibitor of phosphate transport (NaPi-2b, PiT-1, PiT-2) on intestinal phosphate absorption in patients receiving intermittent hemodialysis therapy. Two cross-over, randomized order studies of identical design (ten patients each) compared daily EOS789 50 mg to placebo with meals and daily EOS789 100 mg vs EOS789 100 mg plus 1600 mg sevelamer with meals. Patients ate a controlled diet of 900 mg phosphate daily for two weeks and began EOS789 on day four. On day ten, a phosphate absorption testing protocol was performed during the intradialytic period. Intestinal fractional phosphate absorption was determined by kinetic modeling of serum data following oral and intravenous doses of ³³Phosphate (³³P). The results demonstrated no study drug related serious adverse events. Fractional phosphate absorption was 0.53 (95% confidence interval: 0.39,0.67) for placebo vs. 0.49 (0.35,0.63) for 50 mg EOS789; and 0.40 (0.29,0.50) for 100 mg EOS789 vs. 0.36 (0.26,0.47) for 100 mg EOS789 plus 1600 mg sevelamer (all not significantly different). The fractional phosphate absorption trended lower in six patients who completed both studies with EOS789 100 mg compared with placebo. Thus, in this phase 1b study, EOS789 was safe and well tolerated. Importantly, the use of ³³P as a sensitive and direct measure of intestinal phosphate absorption allows specific testing of drug efficacy. The effectiveness of EOS789 needs to be evaluated in future phase 2 and phase 3 studies.

Impact of community pharmacist-led intensive education on the control of serum phosphate levels in haemodialysis patients

Background Administration of phosphate binders can decrease serum phosphate levels and improve the prognosis of patients on dialysis. However, patients are often non-adherent to phosphate binder medication. Although community pharmacist-led education could be effective in the maintenance of adherence to phosphate binder medication, its impact has not been evaluated. Objective We aimed to evaluate the impact of community pharmacist-led intensive education focusing on phosphate binders for patients receiving haemodialysis. Setting The study comprising three phases (baseline phase, intervention phase, and follow-up phase) was conducted at the Yamauchi Pharmacy, Japan. Method Six pharmacists provided intensive education focusing on phosphate binders to patients receiving haemodialysis. As intensive education, a sheet containing checks for the remaining phosphate binders and information advising the patients on the use of the drugs was issued. Using the check sheet filled in by the patient, the pharmacists repeatedly provided education appropriate to the individual patient's medication status and level of understanding to encourage the correct use of phosphate binders for 8 weeks (intervention phase). We investigated their serum phosphate levels from their medical records from 2 months before the start of intensive education (baseline phase) to 8 months after the end of the education (follow-up phase). Main outcome measure Serum phosphate levels in patients receiving haemodialysis after intensive education by community pharmacists. Results Fifty patients were enrolled in this study. During the intervention phase, serum phosphate levels in the patients with high and the highest serum phosphate level (6-7 mg/dL and ≥ 7 mg/dL, respectively) significantly decreased by 6.9% (P = 0.007) and 10.9% (P = 0.034), respectively. The levels remained below the baseline value throughout the follow-up phase in patients with the highest serum phosphate level. Conclusion Community pharmacist-led education focusing on phosphate binders affects short- and long-term management of serum phosphate levels in patients receiving haemodialysis, especially the patients whose levels were initially high.

Magnesium but not nicotinamide prevents vascular calcification in experimental uraemia

BACKGROUND

Optimal phosphate control is an unmet need in chronic kidney disease (CKD). High serum phosphate increases calcification burden and is associated with mortality and cardiovascular disease in CKD. Nicotinamide (NA) alone or in combination with calcium-free phosphate binders might be a strategy to reduce phosphate levels and calcification and thus impact cardiovascular disease in CKD.

METHODS

We studied the effect of NA alone and in combination with magnesium carbonate (MgCO3) as a potential novel treatment strategy. CKD was induced in dilute brown non-agouti/2 mice by subtotal nephrectomy followed by a high-phosphate diet (HP) and 7 weeks of treatment with NA, MgCO3 or their combination. Control mice underwent subtotal nephrectomy and received an HP or underwent sham surgery and received standard chow plus NA.

RESULTS

CKD mice showed increased serum fibroblast growth factor 23 and calcium-phosphate product that was normalized by all treatment regimes. NA alone increased soft tissue and vascular calcification, whereas any treatment with MgCO3 significantly reduced calcification severity in CKD. While MgCO3 supplementation alone resulted in decreased calcification severity, it resulted in increased intestinal expression of the phosphate transporters type II sodium-dependent phosphate transporter 1 (Pit-1). Combined therapy of MgCO3 and NA reduced tissue calcification and normalized expression levels of intestinal phosphate transporter proteins.

CONCLUSIONS

In conclusion, the data indicate that NA increases while MgCO3 reduces ectopic calcification severity. Augmented expression of intestinal phosphate transporters by MgCO3 treatment was abolished by the addition of NA. However, the clinical relevance of the latter remains to be explored. Importantly, the data suggest no benefit of NA regarding treatment of calcification in addition to MgCO3.

Effect of Sevelamer on Calciprotein Particles in Hemodialysis Patients: The Sevelamer Versus Calcium to Reduce Fetuin-A-Containing Calciprotein Particles in Dialysis (SCaRF) Randomized Controlled Trial

Introduction

Calciprotein particles (CPPs) are potentially modifiable mediators of phosphate toxicity in patients with kidney disease. We compared the effects of calcium carbonate (CC) and the non–calcium-based phosphate binder sevelamer on CPP levels in patients undergoing hemodialysis (HD). We hypothesized that treatment with sevelamer would achieve greater reductions in amorphous calcium phosphate–containing CPP (CPP-1) and hydroxyapatite-containing CPP (CPP-2) owing to reduced calcium loading and anti-inflammatory pleiotropic effects.

Methods

We conducted an open-label, randomized controlled trial (RCT) in which 31 stable prevalent HD patients were allocated to receive either sevelamer hydrochloride (SH), sevelamer carbonate (SC), or CC for 24 weeks. Dual primary endpoints were the between groups differences in serum CPP-1 and CPP-2 levels at 24 weeks in SH + SC–treated versus CC-treated patients. Effects on aortic pulse wave velocity (aPWV), inflammatory cytokines (interleukin-6 and -8), and effects across individual treatment arms were also assessed.

Results

Serum CPP-1, but not CPP-2, levels were lower in those randomly assigned to the sevelamer (SH + SC) group compared with the CC group at 24 weeks (–70%, 95% confidence interval [CI] –90% to –15%, P = 0.02). In subgroup analysis, this effect was confined to those receiving SC (–83.4%, 95% CI –95.7% to –36.8%, P = 0.01). aPWV and interleukin-8 levels were also lower in those who received sevelamer compared with CC at 24 weeks (–2.0 m/s, 95% CI –2.9 to –1.1; –57%, 95% CI –73% to –30%, respectively, both P = 0.01). Conventional markers of mineral metabolism remained stable across all treatment groups.

Discussion

Compared with treatment with CC, use of sevelamer for 24 weeks was associated with lower serum CPP-1 levels and a reduction in aPWV and systemic inflammation.

Effectiveness of phosphate binders in adult patients with end stage renal disease receiving hemodialysis: a systematic review

OBJECTIVES

The objective of the review was to evaluate the effectiveness of the use of phosphate binders on mortality and serum levels of phosphorus, calcium and parathyroid hormone in adult patients with end stage renal disease receiving hemodialysis compared to hemodialysis with no phosphate binder use.

INTRODUCTION

End stage renal disease leading to hemodialysis is a common global health issue. Effective management of this population is focused on balancing alterations in bone mineral markers such as phosphorus, calcium and parathyroid hormone. Chronic imbalances are associated with all-cause mortality. Phosphate binders are a crucial element to regulating these levels.

INCLUSION CRITERIA

The review considered studies including adult patients, age 18 and over, receiving hemodialysis. The intervention of interest was the use of any drug within the class of phosphate binders. Outcomes of interest were all-cause mortality and serum levels of phosphorus, calcium and parathyroid hormone. Experimental and quasi-experimental study designs were considered.

METHODS

A search for relevant published and unpublished literature was conducted through November 5, 2017. Databases searched included PubMed, CINAHL, Embase and Cochrane Central Register of Controlled Trials (CENTRAL), in addition to gray literature sources. Articles that met the inclusion criteria were further assessed for methodological validity by two independent reviewers using the standard critical appraisal instruments from Joanna Briggs Institute. Data were extracted from papers included in the review using the standardized data extraction tool from the Joanna Briggs Institute. Quantitative data were pooled for statistical meta-analysis to evaluate the impact of phosphate binders on phosphorus and calcium.

RESULTS

Seven studies were included in this review. A meta-analysis of four studies showed that the use of phosphate binders resulted in a statistically significant decrease in phosphorus levels compared to placebo (mean difference -1.89 mg/dL, 95% confidence interval -2.03 mg/dL, -1.75 mg/dL); three additional studies described narratively also showed a statistically significant decrease in phosphorus. A meta-analysis of three studies showed a statistically significant increase in calcium compared to placebo (mean difference 0.57 mg/dL, 95% confidence interval 0.50 mg/dL, 0.64 mg/dL); two additional studies described narratively showed no difference in effect on calcium. Of the three studies that measured parathyroid hormone, one showed a statistically significant improvement with the use of phosphate binders (mean difference -83.0 pg/mL, 95% confidence interval -154.63 pg/mL, -11.37 pg/mL) and two showed no difference in effect. No studies measured mortality.

CONCLUSION

Phosphate binders are effective in reducing serum phosphorus. The findings on parathyroid hormone and calcium did not provide adequate support for phosphate binder use. The impact on mortality was not directly measured in any of the included studies.

Sucroferric Oxyhydroxide as Part of Combination Phosphate Binder Therapy among Hemodialysis Patients

BACKGROUND

Combination therapy with multiple phosphate binders is prescribed to reduce elevated serum phosphorus (sP) concentrations among patients on maintenance hemodialysis. Sucroferric oxyhydroxide (SO), an iron-based phosphate binder, has demonstrated efficacy at reducing sP while also being associated with a low pill burden. Whereas the effects of SO monotherapy have been well characterized in clinical trials and observational cohorts, little is known about the effects of SO-containing combination therapy.

METHODS

Patients on hemodialysis (N=234) at Fresenius Kidney Care (FKC) who received ≥120 days of uninterrupted phosphate binder combination therapy with SO were included in this retrospective study. Patient data were censored after SO discontinuation, end of care at FKC, or completion of 12 months of follow-up. Quarterly (Q) changes in phosphate binder pill burden, mean sP, and proportion of patients achieving National Kidney Foundation Kidney Disease Outcomes Quality Initiative (NKF-KDOQI)-recommended sP levels (≤5.5 mg/dl) were compared between baseline (-Q1) and follow-up (Q1-Q4).

RESULTS

Phosphate binder combination therapy with SO was associated with significant increase in the proportion of patients with sP ≤5.5 mg/dl (from 19% at baseline to up to 40% at follow-up; P<0.001) and reduction in sP at all postbaseline time points (from 6.7 mg/dl to 6.2-6.3 mg/dl; P<0.001). Patients on calcium acetate (N=54) and sevelamer (N=94) who added SO therapy at follow-up resulted in a ≥250% increase in patients achieving sP ≤5.5 mg/dl (all P<0.001). Whereas mean phosphate binder pill burden increased with initiation of phosphate binder combination therapy with SO (15.8 pills/d at Q1 versus 12.3 pills/d at -Q1), continued use of SO was associated with down-titration of non-SO phosphate binders such that, by Q4, mean total PB pill burden reduced to 12.3 pills/d.

CONCLUSIONS

For patients on hemodialysis with uncontrolled hyperphosphatemia, combination therapy with SO may allow for sustained improvements in sP control without adversely affecting phosphate binder pill burden.

Multiple Measures of Mineral Metabolism Were Associated With Renal Function in Chinese Centenarians: A Cross-Sectional Study

Background: Chronic kidney disease (CKD) constitutes a public health issue that is estimated to affect more than 10% of global population. Over 100 million people have CKD in China. For the first time, this cross-sectional study was designed to determine whether multiple measures of mineral metabolism had a significant association with renal function in Chinese centenarians. Methods: China Hainan Centenarian Cohort Study was conducted in 18 cities and counties of Hainan Province, China. It utilized the standard methodology for home interview and blood analyses in 750 centenarians including 608 females and 142 males. Results: All centenarians have a median (range) age of 102 (100-115) years, and median (range) level of estimated glomerular filtration rate (eGFR) was 63 (16-138) ml/min/1.73 m². There were 318 centenarians (42.4%) with eGFR levels <60 ml/min/1.73 m². In simple correlation and multivariate linear regression analyses, serum phosphorus, osteocalcin, β-crosslaps, total procollagen type 1 N-terminal propeptide (TP1NP), and parathyroid hormone (PTH) levels were negatively associated with eGFR levels (P < 0.05 for all). Conclusion: The current study supported that serum phosphorus, osteocalcin, β-crosslaps, TP1NP, and PTH levels were negatively associated with eGFR levels, and demonstrated a significant association between multiple measures of mineral metabolism and renal function in Chinese centenarians.

Association of subjective global assessment of nutritional status with gut microbiota in hemodialysis patients: a case-control study

BACKGROUND

Protein-energy wasting (PEW) is prevalent and associated with adverse outcomes in patients with chronic kidney disease (CKD). However, the pathogenesis of PEW in CKD patients has not been fully identified. The gut microbiota has been implicated in the regulation of host metabolism and energy balance. Therefore, we aimed to explore the association between nutritional status and the composition of the gut microbiota in hemodialysis patients.

METHODS

Gut microbial diversity and taxonomy were examined in 88 hemodialysis patients with PEW (n = 22) and normal nutritional status (n = 66) who were matched 1:3 for age and sex. Nutritional status was assessed by using the 7-point subjective global assessment (SGA) score (1-3 = severe PEW; 4-5 = moderate PEW and 6-7 = normal nutrition). The gut microbiota was assessed by 16S ribosomal RNA gene sequencing.

RESULTS

Patients with normal nutritional status had a significantly higher body mass index and physical activity and serum albumin levels, but significantly lower levels of inflammatory cytokines than patients with PEW. The most striking finding was that the α-diversity of the gut microbiota was significantly lower in patients with PEW. In a multivariate analysis, the SGA score was independently and positively associated with α-diversity (P = 0.049). Patients with or without PEW were different with respect to the principal coordinate analysis of β-diversity. Notably, the relative abundance of Faecalibacterium prausnitzii, a butyrate-producing bacteria, was markedly reduced in patients with PEW.

CONCLUSION

In hemodialysis patients, PEW assessed with the SGA was associated with gut dysbiosis.

The Role of Vitamin D in Modulating Mesenchymal Stem Cells and Endothelial Progenitor Cells for Vascular Calcification

Vascular calcification, which involves the deposition of calcifying particles within the arterial wall, is mediated by atherosclerosis, vascular smooth muscle cell osteoblastic changes, adventitial mesenchymal stem cell osteoblastic differentiation, and insufficiency of the calcification inhibitors. Recent observations implied a role for mesenchymal stem cells and endothelial progenitor cells in vascular calcification. Mesenchymal stem cells reside in the bone marrow and the adventitial layer of arteries. Endothelial progenitor cells that originate from the bone marrow are an important mechanism for repairing injured endothelial cells. Mesenchymal stem cells may differentiate osteogenically by inflammation or by specific stimuli, which can activate calcification. However, the bioactive substances secreted from mesenchymal stem cells have been shown to mitigate vascular calcification by suppressing inflammation, bone morphogenetic protein 2, and the Wingless-INT signal. Vitamin D deficiency may contribute to vascular calcification. Vitamin D supplement has been used to modulate the osteoblastic differentiation of mesenchymal stem cells and to lessen vascular injury by stimulating adhesion and migration of endothelial progenitor cells. This narrative review clarifies the role of mesenchymal stem cells and the possible role of vitamin D in the mechanisms of vascular calcification.

Nutritional status and survival of maintenance hemodialysis patients receiving lanthanum carbonate

Background

Hyperphosphatemia and poor nutritional status are associated with increased mortality. Lanthanum carbonate is an effective, calcium-free phosphate binder, but little is known about the long-term impact on mineral metabolism, nutritional status and survival.

Methods

We extended the follow-up period of a historical cohort of 2292 maintenance hemodialysis patients that was formed in late 2008. We examined 7-year all-cause mortality according to the serum phosphate levels and nutritional indicators in the entire cohort and then compared the mortality rate of the 562 patients who initiated lanthanum with that of the 562 propensity score-matched patients who were not treated with lanthanum.

Results

During a mean ± SD follow-up of 4.9 ± 2.3 years, 679 patients died in the entire cohort. Higher serum phosphorus levels and lower nutritional indicators (body mass index, albumin and creatinine) were each independently associated with an increased risk of death. In the propensity score-matched analysis, patients who initiated lanthanum had a 23% lower risk for mortality compared with the matched controls. During the follow-up period, the serum phosphorus levels tended to decrease comparably in both groups, but the lanthanum group maintained a better nutritional status than the control group. The survival benefit associated with lanthanum was unchanged after adjustment for time-varying phosphorus or other mineral metabolism parameters, but was attenuated by adjustments for time-varying indicators of nutritional status.

Conclusions

Treatment with lanthanum is associated with improved survival in hemodialysis patients. This effect may be partially mediated by relaxation of dietary phosphate restriction and improved nutritional status.

A comparison between the combined effect of calcium carbonate with sucroferric oxyhydroxide and other phosphate binders: an in vitro and in vivo experimental study

Background

Approximately 30% of patients on dialysis received combination therapy for their phosphate binder prescription; however, few studies for combined effects of phosphate binders are reported. For the purpose of evaluating the efficacy of combination therapy, we compared the efficacy of sucroferric oxyhydroxide (PA21) combined with calcium carbonate with that of lanthanum carbonate hydrate, sevelamer hydrochloride, and ferric citrate hydrate combined with calcium carbonate.

Methods

For in vitro studies, calcium carbonate and the other phosphate binders alone or in combination were stirred in phosphate solution at pH 2–8 for 2 h. After centrifuging the suspension, the phosphorus level in the supernatant was determined. For in vivo studies, rats were orally administered calcium carbonate and the other phosphate binders (except for sevelamer hydrochloride) alone or in combination, followed by oral administration of phosphate solution adjusted to pH 2 or 7. Serum samples were collected from the rats at predetermined timepoints and the serum phosphorus levels were determined and analyzed using a two-way analysis of variance.

Results

In the in vitro study, the measured phosphate-binding capacity of combining sevelamer hydrochloride, PA21, and lanthanum carbonate hydrate with calcium carbonate was approximately equal to or greater than the theoretical values under most conditions. Furthermore, these combined effects were insensitive to pH in that order. The measured phosphate-binding capacity of ferric citrate hydrate combined with calcium carbonate was smaller than the theoretical values, and the combination did not exhibit efficacy under any of the tested conditions. In the in vivo study, the combined effect of PA21 and calcium carbonate at both pH values and that of lanthanum carbonate hydrate and calcium carbonate at pH 2 were additive. In contrast, the combined effect of lanthanum carbonate hydrate and calcium carbonate at pH 7 and that of ferric citrate hydrate and calcium carbonate at pH 2 were antagonistic.

Conclusions

These results suggest that coadministration of PA21 and calcium carbonate showed good and relatively stable efficacy throughout the range of the gastrointestinal pH and that combining lanthanum carbonate hydrate and ferric citrate hydrate with calcium carbonate may not produce the expected efficacy under certain conditions.

Relationship between serum phosphate levels and survival in chronic hemodialysis patients: interactions with age, malnutrition and inflammation

Background

Evidence indicates that the inverse relationships between phosphate levels and mortality maybe modified by age. Furthermore, malnutrition and inflammation could strengthen the risk associated with phosphate abnormalities. This study aimed to assess the associations between phosphate levels and mortality while accounting for the interactions with age and parameters associated with malnutrition and inflammation in hemodialysis (HD) patients.

Methods

Adult HD patients (n = 245 853) treated in Fresenius Medical Care North America clinics from January 2010 to October 2018 were enrolled. Baseline was defined as Months 4-6 on dialysis, with the subsequent 12 months as the follow-up period. Univariate and multivariate Cox proportional hazard models with spline terms were applied to study the nonlinear relationships between serum phosphate levels and mortality. The interactions of phosphate levels with albumin, creatinine, normalized protein catabolic rate (nPCR) and neutrophil-lymphocyte ratio (NLR) were assessed with smoothing spline analysis of variance Cox proportional hazard models.

Results

Older patients tended to have lower levels of serum phosphate, albumin, creatinine and nPCR. Additionally, both low (<4.0 mg/dL) and high (>5.5 mg/dL) phosphate levels were associated with higher risk of mortality across all age strata. The U-shaped relationships between phosphate levels and outcome persisted even for patients with low or high levels of serum albumin, creatinine, nPCR and NLR, respectively.

Conclusion

The consistent U-shaped relationships between serum phosphate and mortality across age strata and levels of inflammatory and nutritional status should prompt the search for underlying causes and potentially nutritional intervention in clinical practice.

A High Throughput Isolation Method for Phosphate-Accumulating Organisms

Hyperphosphatemia is a secondary issue associated with chronic kidney disorder. Use of phosphate binders and dialysis are the treatments for hyperphosphatemia, albeit with harmful side effects and high cost, respectively. A safer and healthier approach is attempted to administer phosphate-accumulating organisms (PAOs) from probiotics to prevent hyperphosphatemia. However, screening and isolation of PAOs are limited by inefficient enrichment of relevant metabolism and contamination. Therefore, we devised a novel strategy to isolate elite PAOs from Lactobacillus casei JCM 1134 and Bifidobacterium adolescentis JCM 1275 (previously reported PAOs). PAOs were first enriched for phosphate uptake and incubated in low-pH phosphate-free media to dormant non-PAOs, and then purified using Percoll density gradient centrifugation. Subsequently, elite PAOs were isolated from centrifuged pellet on a toluidine blue O-supplemented agar-based media. Using this technique, elite PAOs could not only be isolated, but also semi-quantitatively scored for their phosphate accumulation capabilities. Additionally, these scores correlated well with their accumulated phosphate values. The elite PAOs isolated from L. casei and B. adolescentis showed 0.81 and 0.70 [mg-phosphate/mg-dry cell], respectively (23- and 4.34-fold increase, respectively). Thus, our method can be used to successfully isolate elite PAOs, which might be of use to prevent hyperphosphatemia at early stages.

Serum Chromium Levels Are Higher in Peritoneal Dialysis than in Hemodialysis Patients

Background:An elevation in serum chromium levels in individuals treated with renal replacement therapy has been previously described, but chromium levels have not been systematically studied in patients treated with different dialysis modalities. The aim of this study was to compare serum chromium levels in patients treated with chronic peritoneal dialysis (PD) and hemodialysis (HD).Methods:We studied 169 chronic dialysis patients in a single medical center, of which 148 were treated with HD and 21 with PD. Serum chromium levels were measured by atomic absorption spectrometry.Residual renal function was accessed using a timed urine collection for the measurement of urine output and calculation of glomerular filtration rate (GFR).Results:The median (interquartile range) serum chromium level was significantly higher in patients treated with PD than in patients treated with HD: 5.00 (3.24 - 6.15) vs 1.83 (1.29 - 2.45) mcg/L, p < 0.001. In a univariate analysis, serum chromium level was associated with PD modality: Exp (B) 7.46 (95% confidence interval [CI] 2.1 - 26.4), p = 0.002. The association of PD modality with serum chromium level was even more significant using a multivariate logistic regression model: odds ratio (OR) 11.87 (95% CI 2.85 - 49.52), p = 0.001 after adjustment for age, gender, diabetes, smoking, dialysis vintage, use of diuretics, and residual renal function.Conclusions:In patients treated with chronic dialysis, serum chromium levels are higher in patients treated with PD than in those treated with HD.

Bone and mineral metabolism at 55 haemodialysis centres in Lima

BACKGROUND

Mineral and bone metabolism disorders are common complications in haemodialysis patients that present significant geographical variability.

OBJECTIVES

The objective of this study was to assess these disorders for the first time in haemodialysis patients from Peru.

METHODS

The study included 1551 haemodialysis patients from 55 centres affiliated with the Social Health System of Peru in the city of Lima. Demographic data, comorbidities, treatments and biochemical parameters were collected from each patient. Serum calcium, phosphorus and PTH levels were categorised according to the recommended ranges in the KDOQI and KDIGO guidelines.

RESULTS

The mean age of the patients was 59.5±15.6 years, with a mean time on haemodialysis of 58.0±54.2 months. All patients were dialysed with a calcium concentration in the dialysis fluid of 3.5 mEq/l and 68.9% of patients were prescribed phosphate-binding agents (98.4% of them calcium carbonate). A high percentage of patients showed serum calcium above, and serum phosphorus below, the recommended ranges in the KDOQI guidelines (32.8% and 37.3%, respectively). More than half of the patients had serum PTH values below the recommended ranges of both the KDOQI and KDIGO guidelines (56.4% and 51.6%, respectively).

CONCLUSIONS

Patients included in this study were younger than those from other studies and showed both hypophosphataemia and suppressed PTH, probably due to an excessive calcium overload through dialysis fluid and the use of calcium-containing phosphate binding agents.

Differences in phosphatemia and frequency of consumption of dietary sources of phosphorus in hemodialysis patients in southern and northern Brazil

Introduction:

Hyperphosphatemia is associated with unfavorable outcomes, and the percentage of patients presenting with this condition in hemodialysis (HD) in kidney foundation units in the state of Santa Catarina (SC) is historically higher than that of patients in the state of Tocantins (TO).

Objective:

To assess the frequency of consumption of the main dietary sources of phosphorus and to compare them between the two states.

Methodology:

A cross-sectional study was carried out involving 123 patients, 66 of SC and 57 of TO: 52% were men, average age was 46.9 ± 15.7 years, and mean HD time 48 (57-71) months. A food frequency questionnaire (FFQ) with 33 items that are dietary sources of phosphorus was applied. A consumption score was calculated for sources of organic, inorganic, and total phosphorus, and the six-month average of phosphatemia was obtained.

Results:

The mean phosphatemia of SC patients was higher (6.2 ± 1.5 vs 4.7 ± 1.3 mg/dL, p <0001) than TO patients, as well as the prevalence of hyperphosphatemia (62% vs 28%; p <10001). In the total sample, the foods most frequently consumed were milk and beans. Comparing the frequency of consumption between the two states, a significant difference was found in 17 items. In TO, beef and beans were the foods most frequently consumed, and in SC, fourteen other items of the FFQ (pork, sausages, dairy products, etc.) were the most frequently consumed. Phosphatemia correlated with the frequency of consumption of inorganic phosphorus sources.

Conclusion:

the frequency of consumption of several items was different between the states, and this explains the differences in phosphatemia between the two regions.

Can we IMPROVE cardiovascular outcomes through phosphate lowering in CKD? Rationale and protocol for the IMpact of Phosphate Reduction On Vascular End-points in Chronic Kidney Disease (IMPROVE-CKD) study

INTRODUCTION

Patients with chronic kidney disease (CKD) are at heightened cardiovascular risk, which has been associated with abnormalities of bone and mineral metabolism. A deeper understanding of these abnormalities should facilitate improved treatment strategies and patient-level outcomes, but at present there are few large, randomised controlled clinical trials to guide management. Positive associations between serum phosphate and fibroblast growth factor 23 (FGF-23) and cardiovascular morbidity and mortality in both the general and CKD populations have resulted in clinical guidelines suggesting that serum phosphate be targeted towards the normal range, although few randomised and placebo-controlled studies have addressed clinical outcomes using interventions to improve phosphate control. Early preventive measures to reduce the development and progression of vascular calcification, left ventricular hypertrophy and arterial stiffness are crucial in patients with CKD.

METHODS AND ANALYSIS

We outline the rationale and protocol for an international, multicentre, randomised parallel-group trial assessing the impact of the non-calcium-based phosphate binder, lanthanum carbonate, compared with placebo on surrogate markers of cardiovascular disease in a predialysis CKD population-the IM pact of P hosphate R eduction O n V ascular E nd-points (IMPROVE)-CKD study. The primary objective of the IMPROVE-CKD study is to determine if the use of lanthanum carbonate reduces the burden of cardiovascular disease in patients with CKD stages 3b and 4 when compared with placebo. The primary end-point of the study is change in arterial compliance measured by pulse wave velocity over a 96-week period. Secondary outcomes include change in aortic calcification and biochemical parameters of serum phosphate, parathyroid hormone and FGF-23 levels.

ETHICS AND DISSEMINATION

Ethical approval for the IMPROVE-CKD trial was obtained by each local Institutional Ethics Committee for all 17 participating sites in Australia, New Zealand and Malaysia prior to study commencement. Results of this clinical trial will be published in peer-reviewed journals and presented at conferences.

TRIAL REGISTRATION NUMBER

ACTRN12610000650099.

[Short-term effects with sucroferric oxyhydroxide in hemodialysis patients: Experience in NephroCare France]

INTRODUCTION

Despite a better management of hyperphosphatemia in haemodialysis patients observed during the past years, most of them remain insufficiently treated and exposed to bone and cardiovascular complications that are associated with this biological abnormality. The availability of calcium-free phosphate binders among therapeutical options is confirmed to significantly reduce serum phosphate levels without the risk of excess exposure to calcium. Currently sucroferric oxyhydroxyde (SO) is the only iron-based phosphate binder available in France.

METHODS

A cohort of patients prescribed OHS has been extracted from the EUCLID 5 database between June 2016 and December 2017. The effects on bone mineral metabolism and ferritin have been retrospectively studied.

RESULTS

Two hundred and sixty-two patients with OHS prescription have been identified. The OHS treatment duration median was 4.3 months (1.84-10.99). The average midweek phosphatemia decreased significantly after OHS prescription (from 1.99 to 1.83 mmol/L ; P<0.0001) with a significant increase of the proportion of patients (12.1 to 25.7% ; P<0.0001) reaching the phosphate target of 1.5 mmol/L, without significant change in calcemia and PTH. Ferritinemia significantly increased from 362 to 427 μg/L in 3 months (P=0.0049). OHS therapy has been stopped and replaced in 18% of the cases.

DISCUSSION

Among the NephroCare cohort, OHS therapy was efficient to decrease phosphatemia and to increase significantly the proportion of patients in target. There were no short term changes in calcemia and PTH. The slight increase in ferritin confirms the findings of the phase III study and its extension. The effects on the pills count and the OHS side-effects are analyzed from literature. The risk of iron overload and the impact on the anemia management including EPO sparing are currently under study.

CONCLUSION

OHS therapy appears to be a new efficient alternative to non-calcium phosphate binders. A better knowledge of its side effects will help the patients and the physician to optimize the phosphate balance management. The slight increase in ferritin can be considered as an epiphenomenon because of the important iron needs and frequent check of this parameter in the anemia management.

Use of Phosphate Binders in End-Stage Renal Disease: An Experience From a Secondary Care Hospital in United Arab Emirates

Objective:

Hyperphosphatemia in end-stage renal disease (ESRD) is associated with many serious patient-level consequences including cardiovascular events and mortality. The purpose of this study was to investigate the use of phosphate binders in ESRD patients on maintenance hemodialysis.

Materials and Methods:

The study was a prospective observational cohort study including adult ESRD patients undergoing hemodialysis at a secondary hospital in United Arab Emirates. Patient characteristics were compared as per type of phosphate binder used. Bivariate and multivariate multinomial logistic regression analyses were carried out to determine variables that were independently associated with use of different phosphate binders.

Results:

Phosphate binders used at our study site were sevelamer, calcium carbonate, and a combination of sevelamer and calcium carbonate. Bivariate multinomial logistic regression analysis revealed that serum phosphorous (odds ratio [OR]: 0.14, 95% confidence interval [CI]: 0.04–1.09, P = 0.047; OR: 0.10, 95% CI: 0.03–0.89, P = 0.042), calcium (OR: 0.11, 95% CI: 0.02–0.86, P = 0.041; OR: 0.22, 95% CI: 0.01–0.96, P = 0.012), and calcium–phosphorous product (OR: 0.20, 95% CI: 0.06–0.64, P = 0.008; OR: 0.16, 95% CI: 0.05–0.54, P = 0.003) levels were significantly lower in patients on sevelamer per se as well as in patients on combination therapy, respectively when compared to calcium carbonate per se. Multivariate multinomial logistic regression analysis revealed that in sevelamer and combination groups, cardiovascular diseases (OR: 0.12, 95% CI: 0.02–0.65, P = 0.022; OR: 0.10, 95% CI: 0.01–0.88, P = 0.038) were significantly lesser compared to calcium carbonate group after being adjusted for other variables in the model.

Conclusion:

We observed that hyperphosphatemia and related events in our study population were better controlled by sevelamer per se and combination therapy than calcium carbonate per se. Further large scale, multicenter studies are required to confirm and establish these findings.