Public health approach to addressing hyperphosphatemia among dialysis patients

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.

Elevation of phosphate levels impairs skeletal myoblast differentiation

Hyperphosphatemic conditions such as chronic kidney disease are associated with severe muscle wasting and impaired life quality. While regeneration of muscle tissue is known to be reliant on recruitment of myogenic progenitor cells, the effects of elevated phosphate loads on this process have not been investigated in detail so far. This study aims to clarify the direct effects of hyperphosphatemic conditions on skeletal myoblast differentiation in a murine in vitro model. C2C12 murine muscle progenitor cells were supplemented with phosphate concentrations resembling moderate to severe hyperphosphatemia (1.4–2.9 mmol/l). Phosphate-induced effects were quantified by RT-PCR and immunoblotting. Immunohistochemistry was performed to count nuclear positive cells under treatment. Cell viability and metabolic activity were assessed by XTT and BrdU incorporation assays. Inorganic phosphate directly induced ERK-phosphorylation in pre-differentiated C2C12 myoblast cells. While phosphate concentrations resembling the upper normal range significantly reduced Myogenin expression (− 22.5%, p = 0.015), severe hyperphosphatemic conditions further impaired differentiation (Myogenin − 61.0%, p < 0.0001; MyoD − 51.0%; p < 0.0001). Analogue effects were found on the protein level (Myogenin − 42.0%, p = 0.004; MyoD − 25.7%, p = 0.002). ERK inhibition strongly attenuated phosphate-induced effects on Myogenin expression (p = 0.002). Metabolic activity was unaffected by the treatments. Our data point to a phosphate-induced inhibition of myoblast differentiation without effects on cell viability. Serum phosphate levels as low as the upper normal serum range significantly impaired marker gene expression in vitro. Investigation of cellular effects of hyperphosphatemia may help to better define serum cutoffs and modify existing treatment approaches of phosphate binders, especially in patients at risk of sarcopenia.

Sirtuin-1 and Its Relevance in Vascular Calcification

Vascular calcification (VC) is highly associated with cardiovascular disease and all-cause mortality in patients with chronic kidney disease. Dysregulation of endothelial cells and vascular smooth muscle cells (VSMCs) is related to VC. Sirtuin-1 (Sirt1) deacetylase encompasses a broad range of transcription factors that are linked to an extended lifespan. Sirt1 enhances endothelial NO synthase and upregulates FoxOs to activate its antioxidant properties and delay cell senescence. Sirt1 reverses osteogenic phenotypic transdifferentiation by influencing RUNX2 expression in VSMCs. Low Sirt1 hardly prevents acetylation by p300 and phosphorylation of β-catenin that, following the facilitation of β-catenin translocation, drives osteogenic phenotypic transdifferentiation. Hyperphosphatemia induces VC by osteogenic conversion, apoptosis, and senescence of VSMCs through the Pit-1 cotransporter, which can be retarded by the sirt1 activator resveratrol. Proinflammatory adipocytokines released from dysfunctional perivascular adipose tissue (PVAT) mediate medial calcification and arterial stiffness. Sirt1 ameliorates release of PVAT adipokines and increases adiponectin secretion, which interact with FoxO 1 against oxidative stress and inflammatory arterial insult. Conclusively, Sirt1 decelerates VC by means of influencing endothelial NO bioavailability, senescence of ECs and VSMCs, osteogenic phenotypic transdifferentiation, apoptosis of VSMCs, ECM deposition, and the inflammatory response of PVAT. Factors that aggravate VC include vitamin D deficiency-related macrophage recruitment and further inflammation responses. Supplementation with vitamin D to adequate levels is beneficial in improving PVAT macrophage infiltration and local inflammation, which further prevents VC.

Effects of Excessive Dietary Phosphorus Intake on Bone Health

PURPOSE OF REVIEW

The purpose of this review is to provide an overview of dietary phosphorus, its sources, recommended intakes, and its absorption and metabolism in health and in chronic kidney disease and to discuss recent findings in this area with a focus on the effects of inorganic phosphate additives in bone health.

RECENT FINDINGS

Recent findings show that increasing dietary phosphorus through inorganic phosphate additives has detrimental effects on bone and mineral metabolism in humans and animals. There is new data supporting an educational intervention to limit phosphate additives in patients with chronic kidney disease to control serum phosphate. The average intake of phosphorus in the USA is well above the recommended dietary allowance. Inorganic phosphate additives, which are absorbed at a high rate, account for a substantial and likely underestimated portion of this excessive intake. These additives have negative effects on bone metabolism and present a prime opportunity to lower total phosphorus intake in the USA. Further evidence is needed to confirm whether lowering dietary phosphorus intake would have beneficial effects to improve fracture risk.

Effectiveness of educational or behavioral interventions on adherence to phosphate control in adults receiving hemodialysis: a systematic review

BACKGROUND

People with end-stage kidney disease (ESKD) develop impaired excretion of phosphate. Hyperphosphatemia develops in ESKD as a result of the kidney's reduced ability to excrete ingested phosphate load and is characterized by high bone turnover and increased musculoskeletal morbidity including bone pain and muscle weakness. Increased serum phosphate levels are also associated with cardiovascular disease and associated mortality. These effects are significant considering that cardiovascular disease is the leading cause of death in ESKD, making phosphate control a crucial treatment goal.

OBJECTIVES

To determine the effectiveness of education or behavioral interventions on adherence to phosphate control in adults with ESKD receiving hemodialysis (HD).

INCLUSION CRITERIA TYPES OF PARTICIPANTS

Adults aged over 18 years with ESKD undergoing HD, attending dialysis facilities regardless of frequency and duration of treatment sessions per week. Studies with participants receiving hemodiafiltration were excluded.

TYPES OF INTERVENTION(S)/PHENOMENA OF INTEREST

All types of educational and behavioral interventions aimed at improving adherence to dietary phosphate restriction, phosphate binder medication and HD.

TYPES OF STUDIES

Randomized controlled trials (RCTs), non-RCTs, before and after and cohort studies.

OUTCOMES

Outcome measures included serum phosphate levels, patient knowledge and adherence to phosphate control methods, chronic kidney disease (CKD) self-management behavior and perceived self-efficacy for CKD related to phosphate control.

SEARCH STRATEGY

A search was conducted in CINAHL, MEDLINE, The Cochrane Library, Embase, Web of Science, PsycINFO and ProQuest Dissertations and Theses Global to find published studies between January 2005 and December 2015.

METHODOLOGICAL QUALITY

Risk of bias was assessed by three reviewers prior to inclusion in the review using standardized critical appraisal instruments from the Joanna Briggs Institute Meta-Analysis of Statistics Assessment and Review Instrument (JBI-MAStARI).

DATA EXTRACTION

Data were extracted using the standardized data extraction tool from JBI-MAStARI.

DATA SYNTHESIS

Data were pooled using JBI software. Mean differences (95% confidence interval [CI]) and effect size estimates were calculated for continuous outcomes. Meta-analysis using a random-effects model was performed for serum phosphate levels, and where the findings could not be pooled using meta-analysis, results have been presented in a narrative form. Standard GRADE (Grading of Recommendations Assessment, Development and Evaluation) evidence assessment of outcomes has been reported.

RESULTS

A total of 18 studies were included in the review: seven studies focused on dietary phosphate, four studies focused on medications (phosphate binders) and six studies focused on dietary phosphate and medications. Only one study taught patients about diet, medications and HD to control phosphate. Sixteen studies showed significant improvements in phosphate levels. Meta-analysis of eight RCTs favored educational or behavioral interventions over standard care for serum phosphate control, with a weighted mean reduction of -0.23 mmol/l (95% CI -0.37, -0.08) in treatment groups.

CONCLUSION

Overall, educational or behavioral interventions increase adherence to phosphate control. Studies in this systematic review revealed improved outcomes on serum phosphate levels, patient knowledge and adherence to phosphate control methods, CKD self-management behavior and perceived self-efficacy for CKD related to phosphate control. However, there is a lack of sufficient data on how some of the studies implemented their interventions, suggesting that further research is required. Successful strategies that improve and optimize long-term adherence to phosphate control still need to be formulated.

Patient-Reported Factors Associated With Poor Phosphorus Control in a Maintenance Hemodialysis Population

OBJECTIVE

The purpose of this study was to determine the influence of patient-reported medication adherence and phosphorus-related knowledge on phosphorus control and pharmacy-reported adherence to phosphorus binding medication among patients on maintenance hemodialysis.

DESIGN

Retrospective, cross-sectional cohort study.

SUBJECTS

Seventy-nine hemodialysis patients (mean age 64.2 years, SD = 14 years; 46.8% female) in a stand-alone hemodialysis unit within an integrated learning healthcare system. Ten percent (10%) of subjects were Caucasian, 42% Latino, 19% African American, and 29% Asian. Forty-eight percent had diabetes; 72% had BMI ≥ 30. Inclusion criteria included the provision of survey data and having medication refill data available in the pharmacy system. 77.2% had mean phosphorus levels ≤ 5.5 mg/dL; 22.8% had mean phosphorus levels > 5.5 mg/dL.

INTERVENTION

Subjects were administered the 8-item Morisky Medication Adherence Scale (MMAS-8) and also reported on their phosphorus-related knowledge.

MAIN OUTCOME MEASURE

Phosphorus levels within an adequate range.

RESULTS

The mean serum phosphorus level was 4.96 mg/dL (SD = 1.21). In the well-controlled group, mean phosphorus was 4.44 mg/dL (SD = 0.76). In the poorly controlled group, mean phosphorus was 6.69 mg/dL (SD = 0.74). A total of 61% of patients reported at least some unintentional medication nonadherence, and 48% reported intentional medication nonadherence. Phosphorus-specific knowledge was low, with just under half of patients reporting that they could not name two high-phosphorus foods or identify a phosphorus-related health risk. Phosphorus binder-related nonadherence was substantially higher in the uncontrolled than the controlled group. Adjusting for age, individuals with poorer self-reported binder adherence were less likely to have controlled phosphorus levels (odds ratio = 0.71, P = .06).

CONCLUSION

Phosphorus-related non-adherence, but not low phosphorus-specific knowledge, was associated with poorer phosphorus control. Such findings provide important information for the development of evidence-based strategies for improving phosphorus control among patients on dialysis.

The impact of nurse-led education on haemodialysis patients' phosphate binder medication adherence

BACKGROUND

Phosphate binder medication adherence is required to maintain optimal phosphate levels and minimise bone disease in people with end stage kidney disease.

OBJECTIVES

To examine the impact of a nurse-led education intervention on bone disorder markers, adherence to phosphate binder medication and medication knowledge.

DESIGN

Descriptive study with a paired pre-post intervention survey.

PARTICIPANTS

Adults receiving haemodialysis.

METHODS

Twelve-week intervention where patients self-administered their phosphate binder medication at each dialysis treatment. Nurses provided individualised education. Patients completed a pre- and post-intervention survey designed to explore their knowledge of phosphate binders.

RESULTS

There were no statistically significant changes in clinical markers but a significant improvement in the proportion of patients who took their phosphate binder correctly, increasing from 44 to 72% (p = 0.016). There were moderate to large effect size changes for improved knowledge.

CONCLUSIONS

A nurse-led intervention education programme can increase patients' phosphate binder adherence. However, this does not necessarily manifest into improved serum phosphate levels.

Nutritional management of stage 5 chronic kidney disease

Nutrition is a critical issue in the management of patients with stage 5 chronic kidney disease (CKD). Malnutrition is common among these patients and affects their survival and quality of life. A basic knowledge of the nutritional management of stage 5 CKD is essential for all members of the nephrology team to improve patient care. This paper demonstrates that the needs of haemodialysis patients are more complex than those receiving peritoneal dialysis.

Impact of poverty on serum phosphate concentrations in the Third National Health and Nutrition Examination Survey

OBJECTIVE

Increased serum phosphate is associated with adverse health outcomes. High intake of inexpensive processed and fast foods is common in impoverished communities, and is linked with excessive dietary phosphorus intake and elevated serum phosphate concentrations in chronic kidney disease patients. We examined the impact of socioeconomic status on dietary phosphorus intake and serum phosphate concentrations in the general population.

DESIGN

Cross-sectional study.

PARTICIPANTS

A total of 14,261 adult participants in the Third National Health and Nutrition Examination Survey. PREDICTORS AND OUTCOMES: Poverty to income ratio (PIR; family income indexed to the federal poverty level) was the primary index of socioeconomic status. Serum phosphate was the primary outcome variable.

RESULTS

Although estimated phosphorus intake decreased with decreasing quartiles of PIR (P < .001), serum phosphate was inversely associated with PIR (P = .003). The relationship between lower PIR and higher serum phosphate remained significant after adjustment for demographic, laboratory, and dietary intake characteristics (P = .02). Compared with participants in the highest PIR quartile (income >300% of the federal poverty level), participants in the lowest quartile (income < the federal poverty level) had more than twice the odds of hyperphosphatemia (≥ 4.4 mg/dL) in unadjusted and multivariable-adjusted logistic regression analyses (OR, 2.2; 95% CI, 1.5 to 3.2).

CONCLUSIONS

Although lower income was associated with decreased estimated phosphorus intake, increasing poverty was independently linked with increased serum phosphate and higher likelihood of hyperphosphatemia. These findings may indicate that conventional dietary instruments underestimate phosphorus intake, especially among impoverished individuals. Further studies are needed to explore these possibilities.

Extra-phosphate load from food additives in commonly eaten foods: a real and insidious danger for renal patients

BACKGROUND

Restriction of dietary phosphorus is a major aspect of patient care in those with renal disease. Restriction of dietary phosphorus is necessary to control for phosphate balance during both conservative therapy and dialysis treatment. The extra amount of phosphorus which is consumed as a result of phosphate-containing food additives is a real challenge for patients with renal disease and for dieticians because it represents a "hidden" phosphate load. The objective of this study was to measure phosphorus content in foods, common protein sources in particular, and comprised both those which included a listing of phosphate additives and those which did not.

METHODS

Determinations of dry matter, nitrogen, total and soluble phosphate ions were carried out in 60 samples of foods, namely cooked ham, roast breast turkey, and roast breast chicken, of which, 30 were with declared phosphate additives and the other 30 similar items were without additives.

RESULTS

Total phosphorus (290 ± 40 mg/100 g vs. 185 ± 23 mg/100 g, P < .001) and soluble phosphorus (164 ± 25 mg/100 g vs. 100 ± 19 mg/100 g, P < .001) content were higher in products containing additives than in foods without additives. No difference was detected between the 2 groups regarding dry matter (27.2 ± 2.0 g/100 g vs. 26.7 ± 1.9 g/100 g) or total nitrogen (3.15 ± 0.40 g/100 g vs. 3.19 ± 0.40 g/100 g). Consequently, phosphorus intake per gram of protein was much greater in the foods containing phosphorus additives (15.0 ± 3.1 mg/g vs. 9.3 ± 0.7 mg/g, P < .001).

CONCLUSIONS

Our results show that those foods which contain phosphate additives have a phosphorus content nearly 70% higher than the samples which did not contain additives. This creates a special concern because this extra amount of phosphorus is almost completely absorbed by the intestinal tract. These hidden phosphates worsen phosphate balance control and increase the need for phosphate binders and related costs. Information and educational programs are essential to make patients with renal disease aware of the existence of foods with phosphate additives. Moreover, these facts highlight the need for national and international authorities to devote more attention to food labels which should clearly report the amount of natural or added phosphorus.

Circulating fibroblast growth factor 23 in patients with end-stage renal disease treated by peritoneal dialysis is intact and biologically active

CONTEXT

Fibroblast growth factor 23 (FGF23) regulates phosphorus homeostasis and vitamin D metabolism. Circulating FGF23 levels are elevated in inherited and acquired hypophosphatemic disorders that can cause rickets or osteomalacia. Particularly increased concentrations of FGF23 are observed in patients with chronic kidney disease (CKD), in which increased FGF23 is associated with more rapid disease progression, improved bone mineralization, the development of left ventricular hypertrophy, and increased mortality.

OBJECTIVE

Our objective was to determine whether the markedly elevated levels of immunoreactive FGF23 in CKD represent accumulation of intact, biologically active hormone, C-terminal cleavage fragments, or both.

DESIGN

Biologically active FGF23 in plasma from CKD patients treated by peritoneal dialysis was quantified using a cell-based Egr-1 reporter assay; bioactive FGF23 levels were compared with those measured with immunometric FGF23 assays detecting either intact hormone alone or intact hormone and C-terminal fragments.

SETTING AND PATIENTS

Adult and pediatric patients with end-stage renal disease treated with peritoneal dialysis participated in the study at a tertiary referral center.

RESULTS

Serially diluted patient samples revealed levels of bioactive FGF23 that ran in parallel to CHO cell-derived recombinant human FGF23. FGF23 bioactivity was inhibited by an anti-FGF23 antibody. Levels of bioactive and immunoreactive FGF23 were tightly correlated, and Western blot analysis of FGF23 immunoprecipitated with anti-FGF23 antibodies from plasma of dialysis patients revealed only a single prominent protein band, which was indistinguishable from recombinant intact FGF23, without clear evidence for FGF23 fragments.

CONCLUSIONS

Our results provide strong evidence for the conclusion that virtually all circulating FGF23 in dialysis patients is intact and biologically active.

Phosphorus and potassium content of enhanced meat and poultry products: implications for patients who receive dialysis

BACKGROUND AND OBJECTIVES

Uncooked meat and poultry products are commonly enhanced by food processors using phosphate salts. The addition of potassium and phosphorus to these foods has been recognized but not quantified.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We measured the phosphorus, potassium, and protein content of 36 uncooked meat and poultry products: Phosphorus using the Association of Analytical Communities (AOAC) official method 984.27, potassium using AOAC official method 985.01, and protein using AOAC official method 990.03.

RESULTS

Products that reported the use of additives had an average phosphate-protein ratio 28% higher than additive free products; the content ranged up to almost 100% higher. Potassium content in foods with additives varied widely; additive free products all contained <387 mg/100 g, whereas five of the 25 products with additives contained at least 692 mg/100 g (maximum 930 mg/100 g). Most but not all foods with phosphate and potassium additives reported the additives (unquantified) on the labeling; eight of 25 enhanced products did not list the additives. The results cannot be applied to other products. The composition of the food additives used by food processors may change over time.

CONCLUSIONS

Uncooked meat and poultry products that are enhanced may contain additives that increase phosphorus and potassium content by as much as almost two- and three-fold, respectively; this modification may not be discernible from inspection of the food label.

Phosphorus binders and survival on hemodialysis

Although hyperphosphatemia is a risk factor for mortality, there are limited data on whether therapy with phosphorus binders affects survival. We analyzed a prospective cohort study of 10,044 incident hemodialysis patients using Cox proportional hazards analyses to compare 1-yr all-cause mortality among patients who were or were not treated with phosphorus binders. We performed intention-to-treat analyses to compare patients who began treatment with phosphorus binders during the first 90 d after initiating hemodialysis (n = 3555) with those who remained untreated during that period (n = 5055). We also performed as-treated analyses that modeled phosphorus binder treatment as a time-dependent exposure. We compared survival in a subcohort of treated (n = 3186) and untreated (n = 3186) patients matched by their baseline serum phosphate levels and propensity score of receiving phosphorus binders during the first 90 d. One-year mortality was 191 deaths/1000 patient-years at risk. Treatment with phosphorus binders was independently associated with decreased mortality compared with no treatment in the intention-to-treat, as-treated, and matched analyses. The results were independent of baseline and follow-up serum phosphate levels and persisted in analyses that excluded deaths during the first 90 d of hemodialysis. In summary, treatment with phosphorus binders is independently associated with improved survival among incident hemodialysis patients. Although confirmatory studies are needed in the dialysis setting, future placebo-controlled, randomized trials of phosphorus binders might focus on predialysis patients with chronic kidney disease and normal serum phosphate levels.