Tenapanor: A Phosphate Absorption Inhibitor for the Management of Hyperphosphatemia in Patients with Kidney Failure.

Because of increased risks of cardiovascular disease and death, patients with hyperphosphatemia receiving maintenance dialysis are advised to limit phosphorus consumption and are prescribed phosphate binders in an effort to better control serum phosphate concentrations. Because of large pill size, pill burden, and tolerability issues, phosphate binder adherence is relatively poor. On ingestion, phosphate is absorbed from the intestine via transcellular or paracellular transport. Data show that inhibiting sodium-hydrogen exchanger 3 modulates paracellular phosphate absorption (the predominant pathway in humans). Tenapanor is a first-in-class, minimally absorbed, phosphate absorption inhibitor that selectively inhibits sodium-hydrogen exchanger 3, with a mechanism distinct from, and complementary to, that of phosphate binders. In phase 3 and postregistrational studies, tenapanor conferred statistically significant and clinically meaningful reductions in serum phosphate in patients receiving maintenance dialysis with hyperphosphatemia. Here, we review the available preclinical and clinical data on the effects of tenapanor on controlling intestinal phosphate absorption.

The risk of medically uncontrolled secondary hyperparathyroidism depends on parathyroid hormone levels at haemodialysis initiation.

BACKGROUND: Optimal parathyroid hormone (PTH) control during non-dialysis chronic kidney disease (ND-CKD) might decrease the subsequent risk of parathyroid hyperplasia and uncontrolled secondary hyperparathyroidism (SHPT) on dialysis. However, the evidence for recommending PTH targets and therapeutic strategies is weak for ND-CKD. We evaluated the patient characteristics, treatment patterns and PTH control over the first year of haemodialysis (HD) by PTH prior to HD initiation. METHODS: We studied 5683 incident HD patients from 21 countries in Dialysis Outcomes and Practice Patterns Study Phases 4-6 (2009-18). We stratified by PTH measured immediately prior to HD initiation and reported the monthly prescription prevalence of active vitamin D and calcimimetics over the first year of HD and risk of PTH >600 pg/mL after 9-12 months on HD. RESULTS: The 16% of patients with PTH >600 pg/mL prior to HD initiation were more likely to be prescribed active vitamin D and calcimimetics during the first year of HD. The prevalence of PTH >600 pg/mL 9-12 months after start of HD was greater for patients who initiated HD with PTH >600 (29%) versus 150-300 (7%) pg/mL (adjusted risk difference: 19%; 95% confidence interval : 15%, 23%). The patients with sustained PTH >600 pg/mL after 9-12 months on HD were younger, more likely to be black, and had higher serum phosphorus and estimated glomerular filtration rates at HD initiation. CONCLUSIONS: Increased PTH before HD start predicted a higher PTH level 9-12 months later, despite greater use of active vitamin D and calcimimetics. More targeted PTH control during ND-CKD may influence outcomes during HD, raising the need for PTH target guidelines in these patients.

Serum-to-dialysate potassium gradient and its association with short-term outcomes in hemodialysis patients.

Background: A high serum-to-dialysate potassium (K+) gradient at the start of dialysis leads to rapid lowering of serum K+ and may confer a greater risk of adverse events. Here, we examined the near-term association of K+ gradient with clinical outcomes. Methods: This retrospective (2010-11) event-based study considered 830 741 patient-intervals, each defined by a pre-dialysis measurement of serum K+ made among adult Medicare Parts A and B enrollees who received in-center hemodialysis on a Monday/Wednesday/Friday schedule at a large US dialysis organization. K+ gradient was considered based on the difference in K+ concentration (serum-dialysate) on the date of measurement; analyses accounted for multiple observations per patient. Outcomes considered were: all-cause and cardiovascular hospital admissions, emergency department (ED) visits and deaths. Results: Higher K+ gradient was associated with younger age, greater fistula use, lower comorbidity scores and better nutritional indices. Adjusting for patient differences, there was a dose-response relationship between higher K+ gradient and greater risks of all-cause hospitalization and ED visit. A similar trend was seen for cardiovascular hospitalization but did not achieve statistical significance. No associations were observed with mortality, potentially due to a low number of events. Conclusions: Higher K+ gradient is independently associated with greater risk of all-cause hospitalizations and ED visits. Further research is needed to determine whether interventions that reduce the K+ gradient ameliorate this risk.

Serum Potassium and Short-term Clinical Outcomes Among Hemodialysis Patients: Impact of the Long Interdialytic Interval.

BACKGROUND: Hyperkalemia is common among hemodialysis patients and is associated with morbidity and mortality. The long interdialytic interval is likewise associated with adverse outcomes. However, the interplay among serum potassium, dialysis cycle phase, and clinical outcomes has not been examined. STUDY DESIGN: Retrospective observational study. SETTING & PARTICIPANTS: 52,734 patients receiving in-center hemodialysis at a large dialysis organization during 2010 and 2011 contributed 533,889 potassium measurements (230,634 on Monday; 285,522 on Wednesday; 17,733 on Friday). PREDICTOR: Serum potassium concentration, day of the week of potassium measurement. OUTCOMES: Death, hospitalization, emergency department (ED) visit. RESULTS: There was a significant association between higher serum potassium and risk of hospitalization within 96 hours that was of greater magnitude on Fridays (389 hospitalizations) than Mondays or Wednesdays (4,582 and 4,629 hospitalizations, respectively; P for interaction = 0.008). Serum potassium of 5.5 to <6.0 (vs the referent category of 4.0-<4.5 mEq/L) was associated with increased risk of hospitalization on Fridays, with an adjusted OR of 1.68 (95% CI, 1.22-2.30). However, serum potassium of 5.5 to <6.0 mEq/L was associated with only mild elevation of risk on Mondays and no significantly increased risk on Wednesdays (adjusted ORs of 1.12 [95% CI, 1.00-1.24] and 1.04 [95% CI, 0.94-1.16], respectively). Associations of elevated serum potassium (6.0-<6.5 mEq/L or greater) with death and ED visit were significant, but did not differ based on day of the week. LIMITATIONS: There were insufficient observations to detect effect modification by day of the week for deaths, ED visits, and specific causes of hospitalizations. Confounding may have influenced results. CONCLUSIONS: Higher serum potassium is associated with increased short-term risk of hospitalization, ED visit, and death. The association between serum potassium and hospitalization risk is modified by day of the week, consistent with a contribution of accumulated potassium to adverse outcomes following the long interdialytic interval. Further work is needed to determine whether directed interventions ameliorate this risk.

Patiromer Lowers Serum Potassium When Taken without Food: Comparison to Dosing with Food from an Open-Label, Randomized, Parallel Group Hyperkalemia Study.

BACKGROUND: Patiromer is a sodium-free, nonabsorbed, potassium binder approved for treatment of hyperkalemia. This open-label study compares the efficacy and safety of patiromer administered without food versus with food. METHODS: Adults with hyperkalemia (potassium ≥5.0 mEq/L) were randomized (1:1) to receive patiromer once daily without food or with food for 4 weeks. The dosage was adjusted (maximum: 25.2 g/day) using a prespecified titration schedule to achieve and maintain potassium within a target range (3.8-5.0 mEq/L). The primary efficacy endpoint was the proportion of patients with serum potassium in the target range at either week 3 or week 4. Safety was assessed by adverse events (AEs) and laboratory testing. RESULTS: Efficacy was evaluated in 112 patients; 65.2% were ≥65 years of age, 75.9% had chronic kidney disease, and 82.1% had diabetes. Baseline mean serum potassium was similar in the without-food (5.44 mEq/L) and with-food (5.34 mEq/L) groups. The primary endpoint was achieved by 87.3% (95% CI 75.5-94.7) and 82.5% (95% CI 70.1-91.3) of patients in the with-food and without-food groups, respectively; least squares mean changes in serum potassium from baseline to week 4 were -0.65 and -0.62 mEq/L, respectively (p < 0.0001). The most common AEs were diarrhea and constipation. Serum K+ remained ≥3.5 mEq/L in all patients; 5 patients developed serum magnesium <1.4 mg/dL, including 4 whose baseline magnesium was below the lower limit of normal. CONCLUSION: Patiromer is equally effective and well tolerated when taken without food or with food, thereby offering the potential for dosing flexibility.

Calcium Balance in Chronic Kidney Disease.

PURPOSE OF REVIEW: The kidneys play a critical role in the balance between the internal milieu and external environment. Kidney failure is known to disrupt a number of homeostatic mechanisms that control serum calcium and normal bone metabolism. However, our understanding of calcium balance throughout the stages of chronic kidney disease is limited and the concept of balance itself, especially with a cation as complex as calcium, is often misunderstood. Both negative and positive calcium balance have important implications in patients with chronic kidney disease, where negative balance may increase risk of osteoporosis and fracture and positive balance may increase risk of vascular calcification and cardiovascular events. Here, we examine the state of current knowledge about calcium balance in adults throughout the stages of chronic kidney disease and discuss recommendations for clinical strategies to maintain balance as well as future research needs in this area. RECENT FINDINGS: Recent calcium balance studies in adult patients with chronic kidney disease show that neutral calcium balance is achieved with calcium intake near the recommended daily allowance. Increases in calcium through diet or supplements cause high positive calcium balance, which may put patients at risk for vascular calcification. However, heterogeneity in calcium balance exists among these patients. Given the available calcium balance data in this population, it appears clinically prudent to aim for recommended calcium intakes around 1000 mg/day to achieve neutral calcium balance and avoid adverse effects of either negative or positive calcium balance. Assessment of patients' dietary calcium intake could further equip clinicians to make individualized recommendations for meeting recommended intakes.

Effect of Etelcalcetide vs Placebo on Serum Parathyroid Hormone in Patients Receiving Hemodialysis With Secondary Hyperparathyroidism: Two Randomized Clinical Trials.

Importance: Secondary hyperparathyroidism contributes to extraskeletal complications in chronic kidney disease. Objective: To evaluate the effect of the intravenous calcimimetic etelcalcetide on serum parathyroid hormone (PTH) concentrations in patients receiving hemodialysis. Design, Setting, and Participants: Two parallel, phase 3, randomized, placebo-controlled treatment trials were conducted in 1023 patients receiving hemodialysis with moderate to severe secondary hyperparathyroidism. Trial A was conducted in 508 patients at 111 sites in the United States, Canada, Europe, Israel, Russia, and Australia from March 12, 2013, to June 12, 2014; trial B was conducted in 515 patients at 97 sites in the same countries from March 12, 2013, to May 12, 2014. Interventions: Intravenous administration of etelcalcetide (n = 503) or placebo (n = 513) after each hemodialysis session for 26 weeks. Main Outcomes and Measures: The primary efficacy end point was the proportion of patients achieving greater than 30% reduction from baseline in mean PTH during weeks 20-27. A secondary efficacy end point was the proportion of patients achieving mean PTH of 300 pg/mL or lower. Results: The mean age of the 1023 patients was 58.2 (SD, 14.4) years and 60.4% were men. Mean PTH concentrations at baseline and during weeks 20-27 were 849 and 384 pg/mL vs 820 and 897 pg/mL in the etelcalcetide and placebo groups, respectively, in trial A; corresponding values were 845 and 363 pg/mL vs 852 and 960 pg/mL in trial B. Patients randomized to etelcalcetide were significantly more likely to achieve the primary efficacy end point: in trial A, 188 of 254 (74.0%) vs 21 of 254 (8.3%; P < .001), for a difference in proportions of 65.7% (95% CI, 59.4%-72.1%) and in trial B, 192 of 255 (75.3%) vs 25 of 260 (9.6%; P < .001), for a difference in proportions of 65.7% (95% CI, 59.3%-72.1%). Patients randomized to etelcalcetide were significantly more likely to achieve a PTH level of 300 pg/mL or lower: in trial A, 126 of 254 (49.6%) vs 13 of 254 (5.1%; P < .001), for a difference in proportions of 44.5% (95% CI, 37.8%-51.2%) and in trial B, 136 of 255 (53.3%) vs 12 of 260 (4.6%; P < .001), for a difference in proportions of 48.7% (95% CI, 42.1%-55.4%). In trials A and B, respectively, patients receiving etelcalcetide had more muscle spasms (12.0% and 11.1% vs 7.1% and 6.2% with placebo), nausea (12.4% and 9.1% vs 5.1% and 7.3%), and vomiting (10.4% and 7.5% vs 7.1% and 3.1%). Conclusions and Relevance: Among patients receiving hemodialysis with moderate to severe secondary hyperparathyroidism, use of etelcalcetide compared with placebo resulted in greater reduction in serum PTH over 26 weeks. Further studies are needed to assess clinical outcomes as well as longer-term efficacy and safety. Trial Registration: clinicaltrials.gov Identifiers: NCT01788046.

Patiromer Decreases Serum Potassium and Phosphate Levels in Patients on Hemodialysis.

BACKGROUND: Persistent hyperkalemia (serum potassium (K) ≥5.5 mEq/l) is a common condition in hemodialysis (HD) patients, is associated with increased mortality, and treatment options are limited. The effect of patiromer, a gastrointestinal K binder, on serum K was examined in HD patients. METHODS: Six hyperkalemic HD patients (5 anuric) were admitted to clinical research units for 15 days (1 pretreatment week and 1 patiromer treatment week) and they received a controlled diet with identical meals on corresponding days of pretreatment and treatment weeks. Phosphate (P) binders were discontinued on admission. Patiromer, 12.6 g daily (divided 4.2 g TID with meals), was started on the Monday morning following the last pretreatment week blood sampling. Serum and 24-hour stool samples were collected daily. RESULTS: Mean ± SE serum K decreased (maximum change per corresponding day, 0.6 ± 0.2 mEq/l, p = 0.009) and fecal K increased 58% on patiromer compared with the pretreatment week. During the pretreatment week, 69.0, 47.6, and 11.9% of patients' serum K values were ≥5.5, ≥6.0, and ≥6.5 mEq/l, respectively. This was reduced to 38.1% (p = 0.009), 11.9% (p < 0.001), and 2.4% (p = 0.2) on patiromer. Following P binder discontinuation, the long interdialytic interval mean ± SE serum P numerically increased from 5.8 ± 0.4 to 7.0 ± 0.5 mg/dl (p = 0.06). On patiromer, P decreased from 7.0 ± 0.5 to 6.2 ± 0.5 mg/dl (p = 0.04). While on patiromer, fecal P numerically increased by 112 ± 72 mg/day (17%; p = 0.1792; range -148 to 344 mg/day). No patient discontinued patiromer because of adverse events (AEs); none had serious AEs. CONCLUSIONS: In 6 hyperkalemic HD patients, patiromer decreased serum K and P levels and increased fecal K.

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

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

Treatment of Secondary Hyperparathyroidism: Results of a Phase 2 Trial Evaluating an Intravenous Peptide Agonist of the Calcium-Sensing Receptor.

BACKGROUND/AIMS: This study evaluated the efficacy and safety of AMG416 (etelcalcitide), a novel peptide agonist of the calcium (Ca)-sensing receptor given intravenously (IV) after each hemodialysis session for the treatment of secondary hyperparathyroidism (SHPT). METHODS: Adult subjects with SHPT on hemodialysis enrolled in a 12-week, dose titration (parent) study followed by an open-label extension phase. AMG416 was administered IV, thrice weekly starting at 5 mg/session and titrated based on the subject's parathyroid hormone (PTH) and albumin-corrected Ca (cCa) to target a PTH of 150-300 pg/ml. Efficacy (percent PTH change from baseline to the efficacy analysis period during the parent study) and safety (open-label extension phase) endpoints were evaluated. RESULTS: Baseline (n = 37) mean (standard error [SE]) PTH was 853 (106 pg/ml). The mean (95% CI) percent change from baseline to the efficacy analysis period in PTH concentration was -53.6% (-60.8, -46.4). The proportion of subjects with ≥30% reduction in PTH from baseline to the efficacy assessment period (EAP) was 89% (32/36; 95% CI 73.9, 96.9). Results by the baseline PTH subgroup (≤700 vs. >700 pg/ml) were comparable for both analyses. The proportion of subjects achieving a PTH ≤300 pg/ml was 56% (n = 20/36) at the efficacy assessment period. The mean (SE) percent changes from baseline to EAP were observed for cCa -15% (1.0%) and phosphorus -10% (3.3%). Adverse events were mild to moderate in severity. The PTH reductions achieved in the parent study were maintained in the open-label extension phase. CONCLUSION: AMG416 was well tolerated and appears to be an effective agent for the treatment of SHPT in patients on hemodialysis.

Effects of phosphate binders in moderate CKD.

Some propose using phosphate binders in the CKD population given the association between higher levels of phosphorus and mortality, but their safety and efficacy in this population are not well understood. Here, we aimed to determine the effects of phosphate binders on parameters of mineral metabolism and vascular calcification among patients with moderate to advanced CKD. We randomly assigned 148 patients with estimated GFR=20-45 ml/min per 1.73 m(2) to calcium acetate, lanthanum carbonate, sevelamer carbonate, or placebo. The primary endpoint was change in mean serum phosphorus from baseline to the average of months 3, 6, and 9. Serum phosphorus decreased from a baseline mean of 4.2 mg/dl in both active and placebo arms to 3.9 mg/dl with active therapy and 4.1 mg/dl with placebo (P=0.03). Phosphate binders, but not placebo, decreased mean 24-hour urine phosphorus by 22%. Median serum intact parathyroid hormone remained stable with active therapy and increased with placebo (P=0.002). Active therapy did not significantly affect plasma C-terminal fibroblast growth factor 23 levels. Active therapy did, however, significantly increase calcification of the coronary arteries and abdominal aorta (coronary: median increases of 18.1% versus 0.6%, P=0.05; abdominal aorta: median increases of 15.4% versus 3.4%, P=0.03). In conclusion, phosphate binders significantly lower serum and urinary phosphorus and attenuate progression of secondary hyperparathyroidism among patients with CKD who have normal or near-normal levels of serum phosphorus; however, they also promote the progression of vascular calcification. The safety and efficacy of phosphate binders in CKD remain uncertain.

Calcium balance in normal individuals and in patients with chronic kidney disease on low- and high-calcium diets.

Calcium balance in chronic kidney disease is poorly understood as calcium deficiency is a stimulus for secondary hyperparathyroidism and consequent bone loss while calcium excess promotes extraosseous calcifications. To help resolve this, we evaluated calcium balance in normal individuals and in patients with chronic kidney disease (CKD) on daily diets containing 800 and 2000 mg elemental calcium. Both normal individuals and patients with late stage 3 and stage 4 CKD were in slightly negative to neutral calcium balance on the 800-mg calcium diet. Normal individuals were in modest positive calcium balance on the 2000-mg diet, while patients with CKD on the same diet were in marked positive calcium balance at least over the 9 days of study; and significantly greater than the normal individuals. Increased calcium intake significantly decreased 1,25-dihydroxy-vitamin D and intact parathyroid hormone levels but did not alter the serum calcium concentration. Thus, our findings have important implications for both preventing calcium deficiency and loading in individuals with late stage 3 and stage 4 CKD.

A review of safety, efficacy, and utilization of erythropoietin, darbepoetin, and peginesatide for patients with cancer or chronic kidney disease: a report from the Southern Network on Adverse Reactions (SONAR).

The erythropoiesis-stimulating agents (ESAs) erythropoietin and darbepoetin prevent transfusions among chemotherapy-associated anemia patients. Clinical trials, meta-analyses, and guidelines identify mortality, tumor progression, and venous thromboembolism (VTE) risks with ESA administration in this setting. Product labels advise against administering ESAs with potentially curative chemotherapy (United States) or to conduct risk-benefit assessments (Europe/Canada). Since 2007, fewer chemotherapy-associated anemia patients in the United States and Europe receive ESAs. ESAs and the erythropoietin receptor agonist peginesatide prevent transfusions among chronic kidney disease (CKD) patients; clinical trials, guidelines, and meta-analyses demonstrate myocardial infarction, stroke, VTE, or mortality risks with ESAs targeting high hemoglobin levels. U.S. labels recommend administering ESAs or peginesatide at doses sufficient to prevent transfusions among dialysis CKD patients. For dialysis CKD patients, Canadian and European labels recommend targeting hemoglobin levels of 10 to 12 g/dL and 11 to 12 g/dL, respectively, with ESAs. ESA utilization for dialysis CKD patients has decreased in the United States.

Outpatient red blood cell transfusion payments among patients on chronic dialysis.

BACKGROUND: Payments for red blood cell (RBC) transfusions are separate from US Medicare bundled payments for dialysis-related services and medications. Our objective was to examine the economic burden for payers when chronic dialysis patients receive outpatient RBC transfusions. METHODS: Using Truven Health MarketScan® data (1/1/02-10/31/10) in this retrospective micro-costing economic analysis, we analyzed data from chronic dialysis patients who underwent at least 1 outpatient RBC transfusion who had at least 6 months of continuous enrollment prior to initial dialysis claim and at least 30 days post-transfusion follow-up. A conceptual model of transfusion-associated resource use based on current literature was employed to estimate outpatient RBC transfusion payments. Total payments per RBC transfusion episode included screening/monitoring (within 3 days), blood acquisition/administration (within 2 days), and associated complications (within 3 days for acute events; up to 45 days for chronic events). RESULTS: A total of 3283 patient transfusion episodes were included; 56.4% were men and 40.9% had Medicare supplemental insurance. Mean (standard deviation [SD]) age was 60.9 (15.0) years, and mean Charlson comorbidity index was 4.3 (2.5). During a mean (SD) follow-up of 495 (474) days, patients had a mean of 2.2 (3.8) outpatient RBC transfusion episodes. Mean/median (SD) total payment per RBC transfusion episode was $854/$427 ($2,060) with 72.1% attributable to blood acquisition and administration payments. Complication payments ranged from mean (SD) $213 ($168) for delayed hemolytic transfusion reaction to $19,466 ($15,424) for congestive heart failure. CONCLUSIONS: Payments for outpatient RBC transfusion episodes were driven by blood acquisition and administration payments. While infrequent, transfusion complications increased payments substantially when they occurred.

Magnesium in chronic kidney disease: unanswered questions.

BACKGROUND: Magnesium ion is critical for life and is integrally involved in cellular function and a key component of normal bone mineral. In health, the kidneys, gastrointestinal tract and bone are responsible for maintaining serum magnesium concentrations in the normal range and magnesium balance. Most clinical disorders involving magnesium, other than chronic kidney disease (CKD), result in hypomagnesemia, either from gastrointestinal or kidney losses. CKD and particularly end-stage kidney disease is the only clinical condition where sustained hypermagnesemia may occur and net magnesium balance may be positive. METHODS: This review will focus on normal magnesium homeostasis and review the literature in CKD with a particular focus on end-stage kidney disease and the potential role of magnesium as a phosphate binder and in cardiovascular and bone health. RESULTS: A number of small to medium-size interventional trials have shown that magnesium-based compounds can serve as effective phosphate binders. Observational studies suggest that higher serum magnesium concentrations in dialysis patients may improve survival and may slow the progression of vascular calcification. While a few small prospective trials support these findings, no large or long-term studies are available. CONCLUSIONS: Magnesium balance remains poorly understood in patients with end-stage kidney disease. While observational and small randomized trials suggest that exogenous administration may be useful as a phosphate binder and may have protective cardiovascular effects in terms of both arrhythmias and vascular calcification, large randomized trials are needed to test these hypotheses.

Changes in hemoglobin level distribution in US dialysis patients from June 2006 to November 2008.

BACKGROUND: Erythropoiesis-stimulating agents (ESAs) have had a positive effect on anemia treatment in dialysis patients. However, several events in recent years, including new clinical study results, ESA product label revisions, and coverage and reimbursement policy changes, have had an impact on ESA dosing patterns and consequently on hemoglobin (Hb) distribution characteristics in this patient population. STUDY DESIGN: Retrospective observational study using patient-level data from approximately 87% of dialysis centers in the United States. SETTING & PARTICIPANTS: Dialysis patients who were receiving outpatient care at dialysis facilities during June 2006-November 2008 were included in this study. PREDICTOR: Recent events affecting ESA treatment practice patterns in US dialysis patients. OUTCOMES & MEASUREMENTS: Hb level distribution. RESULTS: Mean Hb level decreased by 0.37 g/dL during the indicated period. Additionally, standard deviation (SD) of the Hb level distribution decreased by 0.14 g/dL and skewness increased by -0.10. Hb measurements in specific ranges changed as follows: >12 g/dL, decreased by 11.3 percentage points;10-12 g/dL, increased by 9.4 percentage points; and <10 g/dL, increased by 1.9 percentage points. The percentage of patients with Hb level >13 g/dL for > or =3 months decreased by 2.9 percentage points. LIMITATIONS: Potential bias in dialysis center selection and lack of information for patient characteristics. CONCLUSIONS: Recent events affecting ESA use in dialysis patients have had the desired effect of increasing the proportion of Hb measurements within the US Food and Drug Administration recommended target range of 10-12 g/dL and decreasing the proportion of Hb measurements >12 g/dL. However, the proportion of Hb measurements <10 g/dL also has increased. Benefits of a decrease in Hb measurements in the >12 g/dL range need to be considered, together with risks of having low Hb levels.

Psychometric evaluation of the National Kidney Dialysis and Kidney Transplantation Study symptom checklist: reliability and validity.

BACKGROUND: Patient-reported outcomes (PROs) are critical in the evaluation of treatment effectiveness. The National Kidney Dialysis and Kidney Transplantation Study (NKDKTS) symptom checklist was developed in the 1980s as a means to better understand the relationships amongst end-stage renal disease (ESRD), anaemia symptoms and multiple quality of life indicators. Unfortunately, key components of validity and reliability were not established at the time of the study. The present study helps fill this void by evaluating the psychometric properties of the 13-item NKDKTS symptom checklist, a measure of anaemia symptom frequency, in a dialysis population. METHODS: The NKDKTS symptom checklist was administered to 104 dialysis patients in three dialysis units at baseline, 48 h and 7 days. Internal consistency, test-retest reliability and construct validity via known-groups responsiveness were evaluated. RESULTS: Principal components factor analyses produced a single factor at each time point, with all items loading >0.50 across time points, and accounting for 37%, 44% and 46% of the variance at each time point (respectively). Forcing a 2-factor solution across time points yielded a single instance of an item loading more highly on factor 2 (0.57) than on factor 1 (0.53). Internal consistency was good at all three time points (Cronbach's alpha = 0.86, 0.89 and 0.90, respectively). Known-groups validity was evaluated by examining the symptom scores of subjects categorized by haemoglobin level. Subjects with lower haemoglobin levels reported significantly more symptoms, and the point estimates and variance at each haemoglobin level were stable over time. CONCLUSION: The results of this study provide further evidence supporting the validity and reliability of the NKDKTS symptom checklist.

How long is the warranty period for nil or low coronary artery calcium in patients new to hemodialysis?

BACKGROUND: Coronary artery calcification (CAC) is common in patients with advanced chronic kidney disease on dialysis. A sizeable proportion of patients has no or minimal CAC at the inception of dialysis, but it is unclear how long they remain free of it. METHODS: For the purpose of this study, 36 incident hemodialysis patients were submitted to sequential chest computed tomography to quantify CAC at baseline, 6, 12, 18 and 30 months. RESULTS: Among them, 15 had absent or minimal CAC score (CACS 0 to 30) and 21 had a CACS>30 at baseline. Overall, the median baseline CACS was 129 (interquartile range [IQR]=0-709) and it increased to 364 (IQR=8.3-1683) at study completion (182% increase). Among the 15 patients with minimal CACS, only 3 progressed and the median CACS increase was 20, as opposed to 15 of 21 patients with a baseline CACS>30 whose median progression was 431 (p<0.02). The 18 patients who had CACS progression were older (68.5 vs. 57.3 years, p=0.0081) and exhibited a poorer control of mineral metabolism (phosphorus 5.2 vs. 4.9 mg/ dL, p=0.048; corrected calcium x phosphorus product [CaxP] 49.3 vs. 46.2 mg2/dL2, p=0.001) than the patients without progression. On multivariable analysis, independent predictors of progression were baseline CACS (p=0.038) and time-averaged Cax;P (p=0.077). CONCLUSION: These data suggest that absent or low CAC at baseline is associated with minimal progression even up to 30 months. Careful management of mineral metabolism appears to be one of the main factors that limit progression of CAC.

Hemoglobin variability in chronic kidney disease: a cross-sectional study.

BACKGROUND: The ability to maintain dialysis patients' hemoglobin (Hgb) within narrow targets remains a significant clinical problem. This study was designed to determine the variability in Hgb values for patients with chronic kidney disease (CKD) receiving or not receiving erythropoiesis-stimulating agents (ESAs) compared with patients on dialysis receiving ESAs. METHODS: This cross-sectional review of anemia management in CKD and dialysis patients analyzed Hgb variability by patient-year, defined as the coefficient of variability calculated for individual patients. One hundred thirty-seven CKD patient-years and 350 dialysis patient-years were available for analysis. Hgb variability was defined as the coefficient of variability calculated as the individual patient's Hgb standard deviation divided by the patient's mean Hgb times 100. RESULTS: The coefficient of variability in Hgb values were significantly less in patients with CKD not treated with ESAs than in patients with CKD treated with ESAs whether they were receiving dialysis (medians: 3.96 versus 8.53%, P < 0.05) or not receiving dialysis (medians: 3.96 versus 7.37%, P < 0.05). CONCLUSION: CKD and hemodialysis patients receiving treatment with ESAs have significantly greater Hgb variability than patients with CKD not receiving ESAs. This finding suggests that the current practice pattern for the administration of exogenous ESAs is partly responsible for the observed Hgb variability.

Interpreting observational studies of disordered mineral metabolism and mortality in patients on hemodialysis.

This Practice Point commentary discusses the findings and limitations of a cohort study reported by Wald and colleagues of mineral metabolism in patients on hemodialysis. The investigators' observational analysis utilized data from the 1,846 patients in the randomized, controlled Hemodialysis (HEMO) Study. Wald et al.'s advantages include the well-characterized dataset, particularly with regard to comorbid conditions. However, the authors found it impossible to analyze the potentially confounding effect of concomitant medications. Furthermore, the relatively small dataset, especially compared with those of previous studies, limits the power of this study. In summary, Wald et al.'s findings support earlier studies confirming the importance of mineral metabolism as a risk factor for mortality in patients on hemodialysis. However, because of its low statistical power, its lack of analysis of potentially important confounders, and its observational design, the study cannot provide appropriate targets and should not serve as a justification for tolerating mild hyperphosphatemia or hypercalcemia or for overlooking the importance of preventing secondary hyperparathyroidism.