Effect of facility-level hemoglobin concentration on dialysis patient risk of transfusion

Temporal Trends in Hemoglobin, Use of Erythropoiesis Stimulating Agents, and Major Clinical Outcomes in Incident Dialysis Patients in Canada

Introduction

Several jurisdictions have adopted a more conservative approach to anemia in patients receiving dialysis amid safety concerns from target hemoglobin studies. It is largely unknown if this has contributed to a change in clinical outcomes.

Methods

A national registry was used to identify 35,945 adult patients who initiated and were maintained on dialysis for ≥90 days in Canada from January 2007 to December 2015. Outcomes were ascertained until March 2017 via linkage with hospital discharge diagnoses. Cox proportional hazards models were used to investigate the association between the era of dialysis initiation and the primary composite outcome (acute myocardial infarction [AMI], stroke, or mortality).

Results

The mean hemoglobin at dialysis initiation decreased from 102.9 g/l in 2007 to 95.5 g/l in 2015, corresponding with a higher prevalence of hemoglobin <80 g/l (8% to 17%) and a reduction in erythropoiesis stimulating agent (ESA) use (49% to 44%). After multivariable adjustment, Era 3 (2013–2015) was associated with an 8% relative risk reduction in the primary outcome compared with Era 1 (2007–2009) (hazard ratio [HR] 0.92, 95% confidence interval [CI] 0.88–0.96), a 10% relative reduction in mortality (HR 0.90, 95% CI 0.85–0.94) but no significant change in AMI or stroke. In a model without era, neither hemoglobin nor ESA use was an independent predictor of outcome.

Conclusion

There have been modest declines in average hemoglobin values and ESA use among incident dialysis patients in Canada with no change in major cardiovascular outcomes. Patient survival has improved over time, likely for reasons other than anemia management.

The efficacy and safety of roxadustat for anemia in patients with chronic kidney disease: a meta-analysis

BACKGROUND

Chronic kidney disease (CKD) is an increasing public health issue. Anemia, which is a complication of CKD, is associated with reduced quality of life and increased morbidity and mortality. Currently quite a few clinical studies have been conducted to compare roxadustat with epoetin alfa [all for dialysis-dependent (DD) patients] or placebo [all for nondialysis-dependent (NDD) patients]. Our meta-analysis aimed to investigate the efficacy and safety of roxadustat for anemia in patients with CKD.

METHODS

We thoroughly searched eight electronic resource databases for randomized controlled trials (RCTs) comparing the efficacy and safety between roxadustat versus epoetin alfa or placebo for the treatment of anemia in patients with CKD.

RESULTS

Four Phase 2 and two Phase 3 studies with 1010 participants were included. Hemoglobin (Hb) and transferrin levels were increased significantly in the roxadustat group versus those in the placebo {standard mean difference [SMD] 1.57 [95% confidence interval (CI) 1.17-1.98]; SMD 1.81 [95% CI 1.53-2.08]; respectively, both low-quality evidence} or epoetin alfa group [SMD 0.47 (95% CI 0.02-0.93), very low-quality evidence; SMD 1.05 (95% CI 0.81-1.29), low-quality evidence; respectively]. Hepcidin levels were reduced significantly in the roxadustat group versus those in the placebo [SMD -1.72 (95% CI -3.03 to -0.41), very low-quality evidence] or epoetin alfa group [SMD -0.23 (95% CI -0.43 to -0.02), low-quality evidence]. Ferritin and serum transferrin saturation (TSAT) levels were reduced significantly in the roxadustat group versus those in the placebo group [SMD -0.82 (95% CI -1.31 to -0.33); SMD -0.54 (95% CI -0.76 to -0.32), respectively; both low-quality evidence] and ferritin and TSAT levels in the roxadustat group were comparable to those in the epoetin alfa group [SMD 0.02 (95% CI -0.18-0.21); SMD 0.15 (95% CI -0.04-0.35), respectively, both low-quality evidence]. As for safety, the incidence of adverse events (AEs) in the roxadustat group was insignificantly different from that of the placebo group [risk ratio (RR) 0.99 (95% CI 0.83-1.18); P = 0.89, very low-quality evidence]. But the incidence of AEs in the roxadustat group was significantly higher than that in the epoetin alfa group [RR 1.25 (95% CI 1.01-1.54); P = 0.04, low-quality evidence]. There was no significant association between roxadustat and the incidence of serious AEs (SAEs) for both NDD and DD patients [RR 1.08 (95% CI 0.51-2.28) and RR 1.43 (95% CI 0.85-2.40), respectively, both very low-quality evidence].

CONCLUSION

In this meta-analysis of RCTs, we found evidence that after the oral administration of roxadustat, NDD patients' Hb levels were increased effectively and DD patients' Hb levels were maintained effectively. The risk of SAEs was not observed with the short-term use of roxadustat. These findings support roxadustat for the treatment of anemia in patients with CKD.

Red cell transfusion in chronic kidney disease in the United States in the current era of erythropoiesis stimulating agents

Anemia is a major complication of chronic kidney disease (CKD) that leads to many symptoms of this disease and worsens cardiovascular health. Treatment of this condition was revolutionized three decades ago by the commercial availability of recombinant human erythropoietin which held the promise of completely eliminating the need for red blood cell transfusion (RBCT). Despite specific therapy now available for anemia in CKD, clinical data accumulated in the last 2 decades suggests that there is a continued need for RBCT, which, we surmise, is due to underutilization of Erythropoietin Stimulating Agents (ESA) or clinical settings such as active bleed, bone marrow resistance such as myelofibrosis or infections where ESAs are ineffective. The purpose of this narrative review is to highlight the adverse effects and summarize the current patterns of RBCT use in all stages of CKD while elaborating on the clinical characteristics of patients that increases their risks of transfusion exposure. We discuss, briefly, salient features of the pathophysiology of anemia in CKD and its contemporary therapies while presenting our perspectives on how to optimize transfusion strategies without compromising patient safety.

Validation of Algorithms Used to Identify Red Blood Cell Transfusion Related Admissions in Veteran Patients with End Stage Renal Disease

Background:

The goal of this study was to compare the performance of several database algorithms designed to identify red blood cell (RBC) Transfusion Related hospital Admissions (TRAs) in Veterans with end stage renal disease (ESRD).

Methods:

Hospitalizations in Veterans with ESRD and evidence of dialysis between 01/01/2008 and 12/31/2013 were screened for TRAs using a clinical algorithm (CA) and four variations of claims-based algorithms (CBA 1–4). Criteria were implemented to exclude patients with non-ESRD-related anemia (e.g., injury, surgery, bleeding, medications known to produce anemia). Diagnostic performance of each algorithm was delineated based on two clinical representations of a TRA: RBC transfusion required to treat ESRD-related anemia on admission regardless of the reason for admission (labeled as TRA) and hospitalization for the primary purpose of treating ESRD-related anemia (labeled TRA-Primary). The performance of all algorithms was determined by comparing each to a reference standard established by medical records review. Population-level estimates of classification agreement statistics were calculated for each algorithm using inverse probability weights and bootstrapping procedures. Due to the low prevalence of TRAs, the geometric mean was considered the primary measure of algorithm performance.

Results:

After application of exclusion criteria, the study consisted of 12,388 Veterans with 26,672 admissions. The CA had a geometric mean of 90.8% (95% Confidence Interval: 81.8, 95.6) and 94.7% (95% CI: 80.5, 98.7) for TRA and TRA-Primary, respectively. The geometric mean for the CBAs ranged from 60.3% (95% CI: 53.2, 66.9) to 91.8% (95% CI: 86.9, 95) for TRA, and from 80.7% (95% CI: 72.9, 86.7) to 96.7% (95% CI: 94.1, 98.2) for TRA-Primary. The adjusted proportions of admissions classified as TRAs was 3.2% (95% CI: 2.8, 3.8) and TRA-Primary was 1.3% (95% CI: 1.1, 1.7).

Conclusions:

The CA and select CBAs were able to identify TRAs and TRA-primary with high levels of accuracy and can be used to examine anemia management practices in ESRD patients.

Hepcidin as a therapeutic target for anemia and inflammation associated with chronic kidney disease

INTRODUCTION

Anemia is a common manifestation of chronic kidney disease (CKD). The pathogenesis of CKD-associated anemia is multifactorial. Our understanding of the molecular control of iron metabolism has improved dramatically because of the discovery of hepcidin and attempts to introduce new drugs to stimulate erythropoiesis or affect the hepcidin-ferroportin pathway have recently emerged. Areas covered: We examine the possible role of hepcidin in iron metabolism and regulation and the potential therapeutic options involving hepcidin and hepcidin-ferroportin axis in renal anemia treatment. We focus on therapeutic targeting of hepcidin, the hepcidin-ferroportin axis and key molecules such as anti-hepcidin antibodies, spigelmers, and anticalins. We also discuss compounds affecting the bone morphogenetic protein receptor [BMP/BMPR] complex and molecules that influence hepcidin, such as hypoxia-inducible factor 1 stabilizers. Expert opinion: Hepcidin is a key regulator of iron availability and is a potential future therapeutic target for managing anemia that is associated with CKD. There are potential risks and benefits associated with novel sophisticated therapies and there are several novel options on the horizon; however, clinical data are currently limited and need development. Inhibition of hepcidin via various pathways might be a viable adjunctive therapeutic option in other clinical situations.

Misdistribution of iron and oxidative stress in chronic kidney disease

Chronic kidney disease (CKD) patients have an extremely high risk of developing cardiovascular diseases (CVD) compared to the general population. Systemic inflammation associated with oxidative stress could be an important determinant of morbidity and mortality associated with CVD. We suspected that dysregulation of iron metabolism should be considered in these patients. Anemia is prevalent in CKD patients and is often treated with erythropoiesis-stimulating agents (ESAs) and iron. In addition, iron administration sometimes causes iron overdose. Excessive iron in the cytosol and mitochondria can accelerate the formation of a highly toxic reactive oxygen species, hydroxyl radicals, which damage lipids, proteins, and DNA. In this review, we propose the following four major reasons for oxidative stress in CKD patients: 1) iron is sequestered in cells by proinflammatory cytokines and hepcidin; 2) the reduction in frataxin increases "free" iron in mitochondria; 3) the accumulation of 5-aminolevulinic acid, a heme precursor, has toxic effects on iron and mitochondrial metabolism; and 4) the elevated levels of the metabolic hormone, leptin, promote hepatic hepcidin production. Although an efficient therapy for preventing oxidative stress in these patients has not yet been well defined, we propose that ESAs for renal anemia may ameliorate these causes of oxidative stress. Further clinical trials are necessary to clarify the effectiveness of ESAs on oxidative stress in CKD patients.

Anemia and mortality in patients with nondialysis-dependent chronic kidney disease

BACKGROUND

A combination of safety concerns and labeling changes impacted use of erythropoiesis-stimulating agents (ESAs) in renal anemia. Data regarding contemporary utilization in pre-dialysis chronic kidney disease (CKD) are lacking.

METHODS

Electronic healthcare records and medical claims data of pre-dialysis CKD patients were aggregated from a large US managed care provider (2011-13). ESA use patterns, characteristics, and outcomes of ESA-treated/untreated patients were quantified.

RESULTS

At baseline, 109/32,308 patients (0.3%) were ESA users. Treated patients were older, had more advanced CKD (58.8% vs 5.4% with stage 4/5 vs 3) and greater prevalence of comorbid diabetes, hypertension, heart failure, and peripheral vascular disease. An additional 266 patients initiated ESA: hemoglobin at initiation was 8-10 g/dL in 193 of these and >10 g/dL in the remainder; 61.7% had stage 4/5 CKD; prevalence of cardiovascular disease was high (50.8% heart failure; 25.2% prior myocardial infarction; 24.1% prior stroke). During follow-up, rates of death and cardiovascular events were higher in baseline ESA users and ESA naives versus non-users.

CONCLUSIONS

ESA use in pre-dialysis CKD patients was exceedingly rare and directed disproportionately to older, sicker patients; these patients had high rates of death and cardiovascular events. These data provide context for contemporary use of ESA in pre-dialysis CKD.

Variability in hemoglobin levels in hemodialysis patients in the current era: a retrospective cohort study

Background: Given regulatory and reimbursement changes in anemia management, we examined hemoglobin variability in a contemporary cohort of maintenance hemodialysis patients. Materials and methods: The study population included > 200,000 hemodialysis patients with Medicare parts A and B as primary payer on October 1, 2012. Based on 25^th and 75^th percentiles, monthly hemoglobin values were categorized as low, intermediate, or high. Six variability categories were created by patterns during the 6-month observation period. Stable categories were: always-low, always-intermediate, always-high; variable patterns were: varying between low and intermediate, intermediate and high, low and high (most-variable). Cox proportional hazard models were used to assess the association between hemoglobin variability and all-cause mortality or major adverse cardiac events (MACE). Results: The 25^th and 75^th hemoglobin percentiles were 10.2 and 11.5 g/dL, respectively, in 2012, vs. 11 and 12.5 g/dL in 2004. ESA doses were lower in all categories in 2012 and transfusion rates higher, particularly for always-low patients. Hemoglobin variability decreased modestly: in 2004, 6.0% were always-intermediate, vs. 9.5% in 2012. In 2012, more patients were always-high and fewer were most-variable. Mortality hazard ratios (HRs) were higher for patients with any low hemoglobin: always-low (HR, 95% CI: 2.07, 1.84 – 2.31), varying between low and intermediate (1.37, 1.29 – 1.45), and most-variable (1.23, 1.16 – 1.31); the pattern was similar for MACE. Conclusions: In 2012 vs. 2004, hemoglobin levels decreased, the range of levels narrowed, and variability decreased modestly; transfusions increased. The highest risk of mortality and MACE appeared to occur in patients with persistently low, rather than highly variable, hemoglobin levels.


Longitudinal Assessment of Renal Perfusion and Oxygenation in Transplant Donor-Recipient Pairs Using Arterial Spin Labeling and Blood Oxygen Level-Dependent Magnetic Resonance Imaging

OBJECTIVES

The aims of this study were to assess renal function in kidney transplant recipients and their respective donors over 2 years using arterial spin labeling (ASL) and blood oxygen level-dependent (BOLD) magnetic resonance imaging (MRI) and to prospectively evaluate the effect of losartan on functional MRI measures in recipients.

MATERIALS AND METHODS

The study included 15 matched pairs of renal transplant donors and recipients. Arterial spin labeling and BOLD MRI of the kidneys were performed on donors before transplant surgery (baseline) and on both donors and recipients at 3 months, 1 year, and 2 years after transplant. After 3 months, 7 of the 15 recipients were prescribed 25 to 50 mg/d losartan for the remainder of the study. A linear mixed-effects model was used to evaluate perfusion, R2*, estimated glomerular filtration rate, and fractional excretion of sodium for changes across time or associated with losartan treatment.

RESULTS

In donors, cortical perfusion in the remaining kidney decreased by 50 ± 19 mL/min per 100 g (11.8%) between baseline and 2 years (P < 0.05), while cortical R2* declined modestly by 0.7 ± 0.3 s-1 (5.6%; P < 0.05). In transplanted kidneys, cortical perfusion decreased markedly by 141 ± 21 mL/min per 100 g (34.2%) between baseline and 2 years (P < 0.001), while medullary R2* declined by 1.5 ± 0.8 s-1 (8.3%; P = 0.06). Single-kidney estimated glomerular filtration rate increased between baseline and 2 years by 17.7 ± 2.7 mL/min per 1.73 m (40.3%; P < 0.0001) in donors and to 14.6 ± 4.3 mL/min per 1.73 m (33.3%; P < 0.01) in recipients. Cortical perfusion at 1 and 2 years in recipients receiving 25 to 50 mg/d losartan was 62 ± 24 mL/min per 100 g higher than recipients not receiving the drug (P < 0.05). No significant effects of losartan were observed for any other markers of renal function.

CONCLUSIONS

The results suggest an important role for noninvasive functional monitoring with ASL and BOLD MRI in kidney transplant recipients and donors, and they indicate a potentially beneficial effect of losartan in recipients.

Performance of a Predictive Model for Long-Term Hemoglobin Response to Darbepoetin and Iron Administration in a Large Cohort of Hemodialysis Patients

Anemia management, based on erythropoiesis stimulating agents (ESA) and iron supplementation, has become an increasingly challenging problem in hemodialysis patients. Maintaining hemodialysis patients within narrow hemoglobin targets, preventing cycling outside target, and reducing ESA dosing to prevent adverse outcomes requires considerable attention from caregivers. Anticipation of the long-term response (i.e. at 3 months) to the ESA/iron therapy would be of fundamental importance for planning a successful treatment strategy. To this end, we developed a predictive model designed to support decision-making regarding anemia management in hemodialysis (HD) patients treated in center. An Artificial Neural Network (ANN) algorithm for predicting hemoglobin concentrations three months into the future was developed and evaluated in a retrospective study on a sample population of 1558 HD patients treated with intravenous (IV) darbepoetin alfa, and IV iron (sucrose or gluconate). Model inputs were the last 90 days of patients’ medical history and the subsequent 90 days of darbepoetin/iron prescription. Our model was able to predict individual variation of hemoglobin concentration 3 months in the future with a Mean Absolute Error (MAE) of 0.75 g/dL. Error analysis showed a narrow Gaussian distribution centered in 0 g/dL; a root cause analysis identified intercurrent and/or unpredictable events associated with hospitalization, blood transfusion, and laboratory error or misreported hemoglobin values as the main reasons for large discrepancy between predicted versus observed hemoglobin values. Our ANN predictive model offers a simple and reliable tool applicable in daily clinical practice for predicting the long-term response to ESA/iron therapy of HD patients.

Multiplanar Reformations in the Measurement of Renal Length on CT: Is It Plain Which Plane to Use?

OBJECTIVE

The objective of this study was to determine the accuracy of renal measurement on CT in multiple imaging planes.

MATERIALS AND METHODS

In this study, three board-certified radiologists retrospectively measured 110 kidneys on CT in 55 consecutive patients. Five measurement methods were used: axial, coronal single image, coronal multiimage, sagittal single image, and sagittal multiimage. The coronal database was sent to a postprocessing workstation, and each radiologist performed a maximum renal measurement using a best off-axis plane that was our reference standard. An ANOVA test with repeated measures and posthoc Bonferroni corrected t tests were performed.

RESULTS

The mean differences (± standard error) compared with the reference standard method were as follows: axial, 7.7 ± 0.7 mm; coronal single image, 13.1 ± 1.4 mm; coronal multiimage, 6.4 ± 0.8 mm; sagittal single image, 6.4 ± 0.6 mm; and sagittal multiimage, 2.8 ± 0.3 mm. The reference standard measurement was larger (p < 0.001), whereas the coronal single-image measurement (p ≤ 0.006) was smaller than all other methods. The sagittal multiimage (p ≤ 0.005) was statistically significantly different from all other methods. There were no statistically significant differences among the axial, coronal multiimage, and sagittal single-image methods (p ≥ 0.088).

CONCLUSION

The single-image coronal method is the least accurate, with an error of approximately 13 mm. The axial, multiimage coronal, and single-image sagittal methods underestimate renal size by approximately 6-8 mm. Multiimage sagittal is the most accurate method for measuring kidneys with an error of approximately 3 mm.

Considerations and challenges in defining optimal iron utilization in hemodialysis

Trials raising concerns about erythropoiesis-stimulating agents, revisions to their labeling, and changes to practice guidelines and dialysis payment systems have provided strong stimuli to decrease erythropoiesis-stimulating agent use and increase intravenous iron administration in recent years. These factors have been associated with a rise in iron utilization, particularly among hemodialysis patients, and an unprecedented increase in serum ferritin concentrations. The mean serum ferritin concentration among United States dialysis patients in 2013 exceeded 800 ng/ml, with 18% of patients exceeding 1200 ng/ml. Although these changes are broad based, the wisdom of these practices is uncertain. Herein, we examine influences on and trends in intravenous iron utilization and assess the clinical trial, epidemiologic, and experimental evidence relevant to its safety and efficacy in the setting of maintenance dialysis. These data suggest a potential for harm from increasing use of parenteral iron in dialysis-dependent patients. In the absence of well powered, randomized clinical trials, available evidence will remain inadequate for making reliable conclusions about the effect of a ubiquitous therapy on mortality or other outcomes of importance to dialysis patients. Nephrology stakeholders have an urgent obligation to initiate well designed investigations of intravenous iron in order to ensure the safety of the dialysis population.