Intravenous iron supplementation practices and short-term risk of cardiovascular events in hemodialysis patients

High-dose intravenous iron reduces myocardial infarction in patients on haemodialysis

AIMS

To investigate the effect of high-dose iron vs. low-dose intravenous (IV) iron on myocardial infarction (MI) in patients on maintenance haemodialysis.

METHODS AND RESULTS

This was a pre-specified analysis of secondary endpoints of the Proactive IV Iron Therapy in Hemodialysis Patients trial (PIVOTAL) randomized, controlled clinical trial. Adults who had started haemodialysis within the previous year, who had a ferritin concentration <400 μg per litre and a transferrin saturation <30% were randomized to high-dose or low-dose IV iron. The main outcome measure for this analysis was fatal or non-fatal MI. Over a median of 2.1 years of follow-up, 8.4% experienced a MI. Rates of type 1 MIs (3.2/100 patient-years) were 2.5 times higher than type 2 MIs (1.3/100 patient-years). Non-ST-elevation MIs (3.3/100 patient-years) were 6 times more common than ST-elevation MIs (0.5/100 patient-years). Mortality was high after non-fatal MI (1- and 2-year mortality of 40% and 60%, respectively). In time-to-first event analyses, proactive high-dose IV iron reduced the composite endpoint of non-fatal and fatal MI [hazard ratio (HR) 0.69, 95% confidence interval (CI) 0.52-0.93, P = 0.01] and non-fatal MI (HR 0.69, 95% CI 0.51-0.93; P = 0.01) when compared with reactive low-dose IV iron. There was less effect of high-dose IV iron on recurrent MI events than on the time-to-first event analysis.

CONCLUSION

In total, 8.4% of patients on maintenance haemodialysis had an MI over 2 years. High-dose compared to low-dose IV iron reduced MI in patients receiving haemodialysis.

EUDRACT REGISTRATION NUMBER

2013-002267-25.

The clinical relevance of detectable plasma iron species in iron overload states and subsequent to intravenous iron-carbohydrate administration

Many disorders of iron homeostasis (e.g., iron overload) are associated with the dynamic kinetic profiles of multiple non-transferrin bound iron (NTBI) species, chronic exposure to which is associated with deleterious end-organ effects. Here we discuss the chemical nature of NTBI species, challenges with measuring NTBI in plasma, and the clinical relevance of NTBI exposure based on source (iron overload disorder vs. intravenous iron-carbohydrate complex administration). NTBI is not a single entity but consists of multiple, often poorly characterized species, some of which are kinetically non-exchangeable while others are relatively exchangeable. Prolonged presence of plasma NTBI is associated with excessive tissue iron accumulation in susceptible tissues, with consequences, such as endocrinopathy and heart failure. In contrast, intravenous iron-carbohydrate nanomedicines administration leads only to transient NTBI appearance and lacks evidence for association with adverse clinical outcomes. Assays to measure plasma NTBI are typically technically complex and remain chiefly a research tool. There have been two general approaches to estimating NTBI: capture assays and redox-activity assays. Early assays could not avoid capturing some iron from transferrin, thus overestimating NTBI. By contrast, some later assays may have promoted the donation of NTBI species to transferrin during the assay procedure, potentially underestimating NTBI levels. The levels of transferrin saturation at which NTBI species have been detectable have varied between different methodologies and between patient populations studied.

Hepatic and cardiac iron overload quantified by magnetic resonance imaging in patients on hemodialysis: A systematic review and meta-analysis

INTRODUCTION

Few studies have reported hepatic and cardiac iron overload in patients with end-stage renal disease (ESRD), and the current evidence regarding the prevalence is still scarce.

AIM

This review aims to estimate the prevalence of hepatic and/or cardiac iron overload quantified by magnetic resonance imaging (MRI) in patients with ESRD who receive hemodialysis (HD), peritoneal dialysis (PD), or have undergone a kidney transplant.

METHODS

A systematic review with meta-analysis was conducted and reported in line with PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analysis) guidelines. MEDLINE and Embase bibliographic databases were searched using a comprehensive list of controlled vocabulary and keywords to identify relevant studies. All studies reporting the prevalence of hepatic and/or cardiac iron overload quantified by MRI in ESRD patients were considered. The Newcastle-Ottawa scale was used to assess the methodological quality of included studies. To investigate the heterogeneity between studies, random-effect meta-analyses for proportions were used.

RESULTS

The review comprised seven studies that included 339 patients. Using meta-analysis, the pooled prevalence of severe and mild to moderate hepatic iron overload quantified by MRI was 0.23 [95% CI: 0.08-0.43] and 0.52 [95% CI: 0.47-0.57], respectively. Only three studies included cardiac iron quantification, and none reported iron overload.

CONCLUSIONS

This review has revealed a high prevalence of severe hepatic iron overload in patients with ESRD treated by HD. Further studies with a larger sample size are needed to determine the impact of iron overload on vital organs in patients with ESRD and guide future research in this understudied field. Proper use of iron chelation and continuous monitoring will help in the early detection of unsolicited complications; however, the low renal clearance of most iron chelators limits the options for treating iron excess in patients with ESRD.

[Evaluation of serum iron as a predictor of a hemoglobin response to injectable iron treatment in chronic hemodialysis patients]

BACKGROUND

The detection and correction of iron deficiency are essential for the treatment of anemia in chronic hemodialysis patients. The aim of our study was to assess the ability of serum iron to predict hemoglobin response to intravenous iron supplementation in hemodialysis patients.

METHODS

It is a retrospective study in 91 hemodialysis patients during 2016 at Clermont-Ferrand University Hospital for whom intravenous iron supplementation had been started. A responder patient was defined as an increase in hemoglobin greater than or equal to 1 g/dL/month and/or a decrease in the dose of erythropoiesis stimulating agent after two months of iron supplementation.

RESULTS

In responding patients, serum iron was significantly lower (6.7 ± 2.7 μmol/L) compared to non-responding patients (8.9±2.9 μmol/L; P<0.001). The positive response to iron supplementation was significantly associated with low serum iron (odds ratio = 0.58 [0.42-0.81]; P=0.002) in a logistic regression model taking into account ferritin, transferrin saturation coefficient, dose variation monthly iron and erythropoiesis stimulating agent and the duration of dialysis. The area under the receiver operating characteristic curve of serum iron, ferritin and transferrin saturation coefficient to predict the response to iron supplementation were 0.72, 0.51 and 0.64, respectively (serum iron versus ferritin [P=0.006] and serum iron versus transferrin saturation coefficient [P=0.04]). The sensitivity for serum iron below 7.5 μmol/L was better than that for ferritin below 86 ng/mL (P<0.001) and the specificity for serum iron below 7.5 μmol/L was better than that for TSC less than 19% (P=0.02).

CONCLUSION

Serum iron below 7.5 μmol/L can predict the success of the response to iron supplementation in chronic hemodialysis patients.

Safety of Intravenous Iron in CKD Stage 3-5 Patients Not on Dialysis: A Retrospective Cohort Study

Background

Iron deficiency is common in chronic kidney disease (CKD) patients not on dialysis (ND). Restoring depleted iron stores through intravenous (IV) route is faster and associated with less side effects. There is conflicting data regarding intravenous iron use and its impact on clinical outcomes in this population.

Objective

This study aims at evaluating any negative clinical impact associated with IV iron use in CKD patients at stages (3-5) before dialysis.

Design

Retrospective chart review.

Setting and Population

Chart analysis of ND CKD 3-5 (estimated glomerular filtration rate [eGFR] <60 mL/min/1.73 m²) patients who received IV iron between January 2013 and January 2018 in 3 major hospitals in Kuwait.

Methods

Outcomes analyzed were rates of all-cause hospitalizations, infection-related hospitalizations, mortality rates, and eGFR decline over 12 months after IV iron infusion in this population divided into 3 groups according to CKD stage.

Results

A total of 738 patients were included in our analysis. Mean initial hemoglobin concentration was 111.5 ± 15.0 g/L in group 1 (CKD 3: eGFR 30-59 mL/min/1.73 m²), 103.6 ± 17.7 g/L in group 2 (CKD 4: eGFR 15-29 mL/min/1.73 m²), and 99.4 ± 14.5 g/L in group 3 (CKD 5: eGFR < 15 mL/min/1.73 m² but not on dialysis). All-cause hospitalization and infection-related hospitalization were more common among group 3 subjects (adjusted odds ratio =2.12 [95% confidence interval, CI: 1.32-3.41] and 2.02 [95% CI: 1.15-3.55]), respectively. No deaths occurred during 12 months of follow-up.

Limitations

Lack of control group, retrospective study.

Conclusion

Intravenous iron use in CKD 3-5 ND is generally safe. Higher hospitalization rates in patients with eGFR <30 mL/min are possibly associated with lower baseline hemoglobin, lower baseline eGFR, and higher comorbidity burden, and not related to iron infusion.

The prevalence of cardiac and hepatic iron overload in patients with kidney failure: A protocol for systematic review and meta-analysis

Introduction

Few studies have reported cardiac and hepatic iron overload in patients with kidney failure or end-stage renal disease and the current evidence regarding the prevalence is still scarce. To the best of the authors' knowledge and following an exhaustive search; no systematic review/meta-analysis has estimated the aggregated prevalence of cardiac and hepatic iron overload in this patient population.

Aim

This review aims to estimate the prevalence of hepatic and/or cardiac iron overload in patients with kidney failure who are receiving hemodialysis, peritoneal dialysis, or underwent kidney transplants.

Methods

A systematic review with meta-analysis will be conducted and reported in line with PRISMA guidelines. MEDLINE and Embase bibliographic databases will be searched using a comprehensive list of controlled vocabularies and keywords to identify relevant studies. All studies reporting the prevalence of hepatic and/or cardiac iron overload prevalence in patients with kidney failure will be considered. Risk of bias assessment for included studies will be conducted based on the study design. StataBE v17 and MetaXL v5.3 will be utilized to perform the meta-analysis.

Discussion

The findings of this systematic review and analysis are expected to give information on the prevalence of iron overload among patients with kidney failure, which will optimize interventions and guide future research in this understudied field.

Improving the safety of intravenous iron treatments for patients with chronic kidney disease

Introduction: Iron-deficiency anemia in chronic kidney disease (CKD) is common and has prognostic, financial, and quality of life implications. Intravenous (IV) iron is a key intervention for optimal management, however, ongoing safety concerns exist. Area covered: The potential side effects associated with IV iron use are addressed as we review the most recent studies. Hypersensitivity reactions and true anaphylaxis are indeed rare with a greater understanding of the nature of labile iron and 'Fishbane' reactions. Hypophosphatemia appears commoner with certain IV iron preparations, however its significance in CKD requires exploration. The long-standing questions regarding oxidative stress and the potential susceptibility to infections and worsening cardiovascular morbidity are discussed. Iron overload secondary to repeat IV iron infusions is plausible, however, a number of guidelines limit and strictly guide prescription. Expert opinion: The past decade has improved our understanding of IV iron administration safety in patients with CKD. Third generation IV iron compounds have minimized hypersensitivity reactions while allowing high doses to be administered safely and rapidly in non-dialysis-dependent CKD patients. However, differences in safety profiles such as hypophosphatemia require further study and therapy should be tailored to the individual. Clinicians should feel confident in using IV iron therapy.

Potential hazards of recent trends in liberal iron use for renal anemia

A randomized controlled trial,the Proactive IV Iron Therapy in Haemodialysis Patients (PIVOTAL), has recently shown that a high-dose (‘proactive’) intravenous iron regimen was superior to a low-dose (‘reactive’) regimen for hemodialysis patient outcomes and overall safety. However, even in the low-dose group, a substantial amount of iron was administered to maintain serum ferritin >200 ng/mL. This type of comparison may have strongly affected the safety results. Iron has two opposite effects on erythropoiesis: it activates erythroid differentiation directly by supplying iron but inhibits it indirectly by stimulating hepcidin and enhancing oxidative stress. Hepcidin plays an essential role not only in iron homeostasis and the anemia of chronic kidney disease, but also in its complications such as atherosclerosis and infection. Its main stimulation by iron—and to a lesser degree by inflammation—should urge clinicians to avoid prescribing excessive amounts of iron. Furthermore, as serum ferritin is closely correlated with serum hepcidin and iron storage, it would seem preferable to rely mainly on serum ferritin to adjust iron administration, defining an upper limit for risk reduction. Based on our estimations, the optimal range of serum ferritin is ∼50–150 ng/mL, which is precisely within the boundaries of iron management in Japan. Considering the contrasting ranges of target ferritin levels between end-stage renal disease patients in Japan and the rest of the world, the optimal range proposed by us will probably be considered as unacceptable by nephrologists abroad. Only well-balanced, randomized controlled trials with both erythropoiesis-stimulating agents and iron will allow us to settle this controversy.

Iron Deficiency in Chronic Kidney Disease: Updates on Pathophysiology, Diagnosis, and Treatment

Anemia is a complication that affects a majority of individuals with advanced CKD. Although relative deficiency of erythropoietin production is the major driver of anemia in CKD, iron deficiency stands out among the mechanisms contributing to the impaired erythropoiesis in the setting of reduced kidney function. Iron deficiency plays a significant role in anemia in CKD. This may be due to a true paucity of iron stores (absolute iron deficiency) or a relative (functional) deficiency which prevents the use of available iron stores. Several risk factors contribute to absolute and functional iron deficiency in CKD, including blood losses, impaired iron absorption, and chronic inflammation. The traditional biomarkers used for the diagnosis of iron-deficiency anemia (IDA) in patients with CKD have limitations, leading to persistent challenges in the detection and monitoring of IDA in these patients. Here, we review the pathophysiology and available diagnostic tests for IDA in CKD, we discuss the literature that has informed the current practice guidelines for the treatment of IDA in CKD, and we summarize the available oral and intravenous (IV) iron formulations for the treatment of IDA in CKD. Two important issues are addressed, including the potential risks of a more liberal approach to iron supplementation as well as the potential risks and benefits of IV versus oral iron supplementation in patients with CKD.

Indoxyl sulfate associates with cardiovascular phenotype in children with chronic kidney disease

BACKGROUND

Cardiovascular disease is the leading cause of death in children with chronic kidney disease (CKD). Serum levels of gut-derived uremic toxins increase with deterioration of kidney function and are associated with cardiac comorbidities in adult CKD patients.

METHODS

Indoxyl sulfate (IS) and p-cresyl sulfate (pCS) were measured by high-performance liquid chromatography in serum of children participating in the Cardiovascular Comorbidity in Children with CKD (4C) Study. Results were correlated with measurements of the carotid intima-media thickness (cIMT), central pulse wave velocity (PWV), and left ventricular mass index (LVMI) in children aged 6-17 years with initial eGFR of 10-60 ml/min per 1.73 m².

RESULTS

The median serum levels of total IS and of pCS, measured in 609 patients, were 5.3 μmol/l (8.7) and 17.0 μmol/l (21.6), respectively. In a multivariable regression model, IS and pCS showed significant positive associations with urea and negative associations with eGFR and uric acid. Furthermore, positive associations of pCS with age, serum albumin, and non-Mediterranean residency and a negative association with glomerular disease were observed. By multivariable regression analysis, only IS was significantly associated with a higher cIMT SDS at baseline and progression of PWV SDS within 12 months, independent of other risk factors.

CONCLUSIONS

Serum levels of gut-derived uremic toxins IS and pCS correlated inversely with eGFR in children. Only IS was significantly associated with surrogate markers of cardiovascular disease in this large pediatric CKD cohort.

Infectious complications and mortality associated with the use of IV iron therapy: a systematic review and meta-analysis

BACKGROUND

Parental iron is used to optimize hemoglobin and enhance erythropoiesis in end-stage renal disease along with erythropoietin-stimulating agents. Safety of iron has been debated extensively and there is no definite evidence whether parenteral iron increases the risk of infections and mortality. We performed this meta-analysis to evaluate the incidence of infectious complications, hospitalizations and mortality with use of parenteral iron.

METHODS

Medical electronic databases [PubMed, EMBASE, Scopus, Web of Science, and cochrane central register for controlled clinical trials (CENTRAL)] were queried for studies that investigated the association between intravenous iron administration and infection in hemodialysis patients. 24 studies (8 Randomized control trials (RCTs) and 16 observational studies) were considered for qualitative and quantitative analysis.

RESULTS

All-cause mortality Data from 6 RCTs show that high-dose IV iron conferred 17% less all-cause mortality compared to controls; however, this outcome was not statistically significant (OR = 0.83, CI [0.7, 1.01], p = 0.07). Nine observational studies were pooled under the random effects model due to significant heterogeneity (I² = 83%, p < 0.001). The overall HR showed increased risk of all-cause mortality in the high-dose group but was statistically non-significant (HR = 1.1, CI [1, 1.22], p = 0.06). Infections Four RCTs with no heterogeneity among their data (I² = 0%, p = 0.61). Under the fixed effect model, there was no difference in the infection rate between high-dose iron and control group (OR = 0.97, CI [0.82, 1.16], p = 0.77); eight observational studies with significant heterogeneity and utilizing random effects model. Summary HR showed increased yet non-significant risk of infection in the high-dose group (HR = 1.13, CI [0.99, 1.28], p = 0.07) Hospitalization 1 RCT and six observational studies provided data for the rate of all-cause hospitalization. There was marked heterogeneity among observational studies. RCT showed no significant difference between high-dose iron and controls in the rate of hospitalization (OR = 1.03, CI [0.87, 1.23], p = 0.71). Summary HR for observational data showed increased rate of hospitalization in the high-dose group; however, this effect was not statistically significant (HR = 1.11, CI [0.99, 1.24], p = 0.07). Cardiovascular events One RCT compared the rate of adverse cardiovascular events between high-dose and low-dose iron. No significant difference was observed between the two groups (22.3% vs 25.6%, p = 0.12). Six heterogeneous observational studies (I² = 65%, p < 0.001) reported on the rate of cardiovascular events. No significant difference was observed between high-dose iron and controls (HR = 1.18, CI [0.89, 1.57], p = 0.24).

CONCLUSION

High-dose parenteral iron does not seem to be associated with higher risk of infection, all-cause mortality, increased hospitalization or increased cardiovascular events on analysis of RCTs. Observational studies show increased risk for all-cause mortality, infections and hospitalizations that were not statistically significant and were associated with significant heterogeneity.

Low hemoglobin at hemodialysis initiation: an international study of anemia management and mortality in the early dialysis period

Background

Anemia at hemodialysis (HD) initiation is common. Correcting low hemoglobin (Hgb) before HD initiation may improve survival by avoiding potential harms of chronic anemia, high doses of erythropoiesis-stimulating agents (ESAs) and intravenous (IV) iron in the early HD period, and/or rapid Hgb rise.

Methods

We included 4604 incident HD patients from 21 countries in the Dialysis Outcomes and Practice Patterns Study Phases 4–5 (2009–15). Because low Hgb at HD start may reflect comorbidity or ESA hyporesponse, we restricted our analysis to the 80% of patients who achieved Hgb ≥10 g/dL 91–120 days after HD start (Month 4).

Results

About 53% of these patients had Hgb <10 g/dL in Month 1 (<30 days after HD start); they were younger with a similar comorbidity profile (versus Hgb ≥10 g/dL). Month 1 Hgb was associated with first-year HD mortality (adjusted hazard ratio for 1 g/dL higher Hgb was 0.89; 95% confidence interval: 0.81–0.97), despite minimal differences in Month 4 Hgb. Patients with lower Hgb in Month 1 received higher doses of ESA, but not IV iron, over the first 3 months of HD. Results were consistent when excluding catheter users or adjusting for IV iron and ESA dose over the first 3 months.

Conclusions

Even among patients with Hgb ≥10 g/dL 3 months later, anemia at HD initiation was common and associated with elevated mortality. A more proactive approach to anemia management in advanced chronic kidney disease (CKD) may thus improve survival on HD, though long-term prospective studies of non-dialysis CKD patients are needed.

Long-Term Risks of Intravenous Iron in End-Stage Renal Disease Patients

Patients with end-stage renal disease on dialysis commonly receive intravenous iron to treat anemia along with erythropoiesis-stimulating agents. While studies of intravenous iron have demonstrated efficacy in raising hemoglobin, the quantity of administered intravenous iron has raised concerns about iron overload leading to long-term toxicities. The goal of this review is to understand recent trends in intravenous iron use, potential mechanisms of iron toxicity, and to evaluate the available evidence in the literature for potential long-term cardiovascular and infectious complications. We include findings from the recently published landmark clinical trial of intravenous iron for patients receiving hemodialysis to contextualize treatment recommendations.

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.

Intravenous Iron in Patients Undergoing Maintenance Hemodialysis

BACKGROUND

Intravenous iron is a standard treatment for patients undergoing hemodialysis, but comparative data regarding clinically effective regimens are limited.

METHODS

In a multicenter, open-label trial with blinded end-point evaluation, we randomly assigned adults undergoing maintenance hemodialysis to receive either high-dose iron sucrose, administered intravenously in a proactive fashion (400 mg monthly, unless the ferritin concentration was >700 μg per liter or the transferrin saturation was ≥40%), or low-dose iron sucrose, administered intravenously in a reactive fashion (0 to 400 mg monthly, with a ferritin concentration of <200 μg per liter or a transferrin saturation of <20% being a trigger for iron administration). The primary end point was the composite of nonfatal myocardial infarction, nonfatal stroke, hospitalization for heart failure, or death, assessed in a time-to-first-event analysis. These end points were also analyzed as recurrent events. Other secondary end points included death, infection rate, and dose of an erythropoiesis-stimulating agent. Noninferiority of the high-dose group to the low-dose group would be established if the upper boundary of the 95% confidence interval for the hazard ratio for the primary end point did not cross 1.25.

RESULTS

A total of 2141 patients underwent randomization (1093 patients to the high-dose group and 1048 to the low-dose group). The median follow-up was 2.1 years. Patients in the high-dose group received a median monthly iron dose of 264 mg (interquartile range [25th to 75th percentile], 200 to 336), as compared with 145 mg (interquartile range, 100 to 190) in the low-dose group. The median monthly dose of an erythropoiesis-stimulating agent was 29,757 IU in the high-dose group and 38,805 IU in the low-dose group (median difference, -7539 IU; 95% confidence interval [CI], -9485 to -5582). A total of 320 patients (29.3%) in the high-dose group had a primary end-point event, as compared with 338 (32.3%) in the low-dose group (hazard ratio, 0.85; 95% CI, 0.73 to 1.00; P<0.001 for noninferiority; P=0.04 for superiority). In an analysis that used a recurrent-events approach, there were 429 events in the high-dose group and 507 in the low-dose group (rate ratio, 0.77; 95% CI, 0.66 to 0.92). The infection rate was the same in the two groups.

CONCLUSIONS

Among patients undergoing hemodialysis, a high-dose intravenous iron regimen administered proactively was superior to a low-dose regimen administered reactively and resulted in lower doses of erythropoiesis-stimulating agent being administered. (Funded by Kidney Research UK; PIVOTAL EudraCT number, 2013-002267-25 .).

Intravenous Irons: From Basic Science to Clinical Practice

Iron is an essential trace mineral necessary for life, and iron deficiency anaemia (IDA) is one of the most common haematological problems worldwide, affecting a sixth of the global population. Principally linked to poverty, malnutrition and infection in developing countries, in Western countries the pathophysiology of IDA is primarily linked to blood loss, malabsorption and chronic disease. Oral iron replacement therapy is a simple, inexpensive treatment, but is limited by gastrointestinal side effects that are not inconsequential to some patients and are of minimal efficacy in others. Third generation intravenous (IV) iron therapies allow rapid and complete replacement dosing without the toxicity issues inherent with older iron preparations. Their characteristic, strongly-bound iron-carbohydrate complexes exist as colloidal suspensions of iron oxide nanoparticles with a polynuclear Fe(III)-oxyhydroxide/oxide core surrounded by a carbohydrate ligand. The physicochemical differences between the IV irons include mineral composition, crystalline structure, conformation, size and molecular weight, but the most important difference is the carbohydrate ligand, which influences complex stability, iron release and immunogenicity, and which is a unique feature of each drug. Recent studies have highlighted different adverse event profiles associated with third-generation IV irons that reflect their different structures. The increasing clinical evidence base has allayed safety concerns linked to older IV irons and widened their clinical use. This review considers the properties of the different IV irons, and how differences might impact current and future clinical practice.

Current misconceptions in diagnosis and management of iron deficiency

The prevention and treatment of iron deficiency is a major public health goal. Challenges in the treatment of iron deficiency include finding and addressing the underlying cause and the selection of an iron replacement product which meets the needs of the patient. However, there are a number of non-evidence-based misconceptions regarding the diagnosis and management of iron deficiency, with or without anaemia, as well as inconsistency of terminology and lack of clear guidance on clinical pathways. In particular, the pathogenesis of iron deficiency is still frequently not addressed and iron not replaced, with indiscriminate red cell transfusion used as a default therapy. In our experience, this imprudent practice continues to be endorsed by non-evidence-based misconceptions. The intent of the authors is to provide a consensus that effectively challenges these misconceptions, and to highlight evidence-based alternatives for appropriate management (referred to as key points). We believe that this approach to the management of iron deficiency may be beneficial for both patients and healthcare systems. We stress that this paper solely presents the Authors' independent opinions. No pharmaceutical company funded or influenced the conception, development or writing of the manuscript.

Safety of Intravenous Iron in Dialysis: A Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVES

The safety of intravenous iron dosing in dialysis is uncertain. Higher-dose intravenous iron may be associated with a higher risk of infections, cardiovascular events, hospitalizations, and mortality. This systematic review aimed to determine the safety of higher-dose versus lower-dose intravenous iron, oral iron, or no iron supplementation in adult patients treated with dialysis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We searched Medline, EMBASE, Cochrane library, and CINAHL from inception to January 6, 2017 for randomized, controlled trials and observational studies comparing higher-dose intravenous iron with lower-dose intravenous iron, oral iron, or no iron in patients treated with dialysis that had all-cause mortality, infection, cardiovascular events, or hospitalizations as outcomes.

RESULTS

Of the 2231 eligible studies, seven randomized, controlled trials and 15 observational studies met inclusion criteria. The randomized, controlled trials showed no association between higher-dose intravenous iron (>400 mg/mo for most studies) and mortality (six studies; n=970; pooled relative risk, 0.93; 95% confidence interval, 0.47 to 1.84; follow-up ranging from 35 days to 26 months) or infection (four studies; n=743; relative risk, 1.02; 95% confidence interval, 0.74 to 1.41). The observational studies showed no association between higher-dose intravenous iron (>200 mg/mo for most studies) and mortality (eight studies; n=241,408; hazard ratio, 1.09; 95% confidence interval, 0.98 to 1.21; follow-up ranging from 3 to 24 months), infection (eight studies; n=135,532; pooled hazard ratio, 1.13; 95% confidence interval, 0.99 to 1.28), cardiovascular events (seven studies; n=135,675; hazard ratio, 1.18; 95% confidence interval, 0.90 to 1.56), or hospitalizations (five studies; n=134,324; hazard ratio, 1.08; 95% confidence interval, 0.97 to 1.19).

CONCLUSIONS

Higher-dose intravenous iron does not seem to be associated with higher risk of mortality, infection, cardiovascular events, or hospitalizations in adult patients on dialysis. Strength of this finding is limited by small numbers of participants and events in the randomized, controlled trials and statistical heterogeneity in observational studies.

Balance of Benefit and Risk in Intravenous Iron Treatment in Chronic Kidney Disease

Iron supplementation is an important aspect of treatment for hemodialysis patients, with most administration by an intravenous route. As with any drug, decisions as to treatment are most meaningful when benefits and risks are weighed in the context of the individual patient's clinical characteristics. In this article, knowledge of benefits and risks of intravenous iron are reviewed.

Renal association clinical practice guideline on Anaemia of Chronic Kidney Disease

Anaemia is a commonly diagnosed complication among patients suffering with chronic kidney disease. If left untreated, it may affect patient quality of life. There are several causes for anaemia in this patient population. As the kidney function deteriorates, together with medications and dietary restrictions, patients may develop iron deficiency, resulting in reduction of iron supply to the bone marrow (which is the body organ responsible for the production of different blood elements). Chronic kidney disease patients may not be able to utilise their own body's iron stores effectively and hence, many patients, particularly those receiving haemodialysis, may require additional iron treatment, usually provided by infusion.With further weakening of kidney function, patients with chronic kidney disease may need additional treatment with a substance called erythropoietin which drives the bone marrow to produce its own blood. This substance, which is naturally produced by the kidneys, becomes relatively deficient in patients with chronic kidney disease. Any patients will eventually require treatment with erythropoietin or similar products that are given by injection.Over the last few years, several iron and erythropoietin products have been licensed for treating anaemia in chronic kidney disease patients. In addition, several publications discussed the benefits of each treatment and possible risks associated with long term treatment. The current guidelines provide advice to health care professionals on how to screen chronic kidney disease patients for anaemia, which patients to investigate for other causes of anaemia, when and how to treat patients with different medications, how to ensure safe prescribing of treatment and how to diagnose and manage complications associated with anaemia and the drugs used for its treatment.

Intravenous iron therapy in patients with chronic kidney disease: recent evidence and future directions

Current recommendations for the use of intravenous iron therapy in the management of anaemia in patients with chronic kidney disease (CKD) are based on limited clinical evidence. Since the publication of the Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guideline for Anaemia in Chronic Kidney Disease in 2012, a number of randomized clinical trials [notably, the Ferinject Assessment in Patients with Iron Deficiency Anaemia (FIND-CKD) and Randomized Trial to Evaluate IV and Oral Iron in Chronic Kidney Disease (REVOKE) trials] and observational studies have been completed, and a further large clinical trial—Proactive IV Iron Therapy in Dialysis Patients (PIVOTAL)—is currently underway. In this article, the implications of the findings from these recent studies are discussed and the critical evidence gaps that remain to be addressed are highlighted.

Iatrogenic iron overload and its potential consequences in patients on hemodialysis

Iron overload was considered rare in hemodialysis patients until recently, but its clinical frequency is now increasingly recognized. The liver is the main site of iron storage and the liver iron concentration (LIC) is closely correlated with total iron stores in patients with secondary hemosiderosis and genetic hemochromatosis. Magnetic resonance imaging (MRI) is now the gold standard method for estimating and monitoring LIC. Studies of LIC in hemodialysis patients by magnetic susceptometry thirteen years ago and recently by quantitative MRI have demonstrated a relation between the risk of iron overload and the use of intravenous (IV) iron products prescribed at doses determined by the iron biomarker cutoffs contained in current anemia management guidelines. These findings have challenged the validity of both iron biomarker cutoffs and current clinical guidelines, especially with respect to recommended IV iron doses. Moreover, three recent long-term observational studies suggested that excessive IV iron doses might be associated with an increased risk of cardiovascular events and death in hemodialysis patients. It has been hypothesized that iatrogenic iron overload in the era of erythropoiesis-stimulating agents might silently increase complications in dialysis patients without creating obvious, clinical signs and symptoms. High hepcidin-25 levels were recently linked to fatal and nonfatal cardiovascular events in dialysis patients. It has been postulated that the main pathophysiological pathway leading to these events might involve the pleiotropic master hormone hepcidin, which regulates iron metabolism, leading to activation of macrophages in atherosclerotic plaques and then to clinical cardiovascular events. Thus, the potential iron overload toxicity linked to chronic administration of IV iron therapy is now becoming one of the most controversial topics in the management of anemia in hemodialysis patients.

Complexity of intravenous iron nanoparticle formulations: implications for bioequivalence evaluation

Intravenous iron formulations are a class of complex drugs that are commonly used to treat a wide variety of disease states associated with iron deficiency and anemia. Venofer® (iron-sucrose) is one of the most frequently used formulations, with more than 90% of dialysis patients in the United States receiving this formulation. Emerging data from global markets outside the United States, where many iron-sucrose similars or copies are available, have shown that these formulations may have safety and efficacy profiles that differ from the reference listed drug. This may be attributable to uncharacterized differences in physicochemical characteristics and/or differences in labile iron release. As bioequivalence evaluation guidance evolves, clinicians should be educated on these potential clinical issues before a switch to the generic formulation is made in the clinical setting.

The role of CORM-2 as a modulator of oxidative stress and hemostatic parameters of human plasma in vitro

PURPOSE

The main aim of the experiment is to examine the effect of CORM-2, a donor of carbon monoxide (CO), on oxidative stress in human plasma in vitro. In addition, it examines the effects of CORM-2 on the hemostatic parameters of plasma: the activated partial thromboplastin time (APTT), thrombin time (TT) and prothrombin time (PT).

METHODS

Human plasma was incubated for 5-60 min with different concentrations of CORM-2: 0.1-100 μM. Following this, various hemostatic factors and biomarkers of oxidative stress were studied. Lipid peroxidation was measured as thiobarbituric acid reactive substance (TBARS) concentration, and the oxidation of amino acid residues in proteins was measured by determining the amounts of carbonyl and thiol groups.

RESULTS

Two oxidative stress inducers: hydrogen peroxide (H2O2) and the donor of hydroxyl radical (H2O2/Fe) were used. Decrease in protein carbonylation, thiol group oxidation and lipid peroxidation were detected at tested concentrations of CORM-2.

CONCLUSION

Our results indicate that CORM-2 may have antioxidant properties in human plasma treated with H2O2 or H2O2/Fe. In addition, our results indicate the anti-coagulant activities of CORM-2 in vitro.

Intravenous iron administration strategies and anemia management in hemodialysis patients

Background

The effect of maintenance intravenous (IV) iron administration on subsequent achievement of anemia management goals and mortality among patients recently initiating hemodialysis is unclear.

Methods

We performed an observational cohort study, in adult incident dialysis patients starting on hemodialysis. We defined IV administration strategies over a 12-week period following a patient's initiation of hemodialysis; all those receiving IV iron at regular intervals were considered maintenance, and all others were considered non-maintenance. We used multivariable models adjusting for demographics, clinical and treatment parameters, iron dose, measures of iron stores and pro-infectious and pro-inflammatory parameters to compare these strategies. The outcomes under study were patients' (i) achievement of hemoglobin (Hb) of 10-12 g/dL, (ii) more than 25% reduction in mean weekly erythropoietin stimulating agent (ESA) dose and (iii) mortality, ascertained over a period of 4 weeks following the iron administration period.

Results

Maintenance IV iron was administered to 4511 patients and non-maintenance iron to 8458 patients. Maintenance IV iron administration was not associated with a higher likelihood of achieving an Hb between 10 and 12 g/dL {adjusted odds ratio (OR) 1.01 [95% confidence interval (CI) 0.93-1.09]} compared with non-maintenance, but was associated with a higher odds of achieving a reduced ESA dose of 25% or more [OR 1.33 (95% CI 1.18-1.49)] and lower mortality [hazard ratio (HR) 0.73 (95% CI 0.62-0.86)].

Conclusions

Maintenance IV iron strategies were associated with reduced ESA utilization and improved early survival but not with the achievement of Hb targets.

Safety of intravenous iron in hemodialysis patients

Among end-stage renal disease patients maintained by hemodialysis, anemia has been managed primarily through erythropoiesis-stimulating agents (ESAs) and intravenous (IV) iron. Following concerns about the cardiovascular (CV) safety of ESAs and changes in the reimbursement policies in Medicare's ESRD program, the use of IV iron has increased. IV iron supplementation promotes hemoglobin production and reduces ESA requirements, yet there exists relatively little evidence on the long-term safety of iron supplementation in hemodialysis patients. Labile iron can induce oxidative stress and is also essential in bacterial growth, leading to concerns about IV iron use and risk of CV events and infections in hemodialysis patients. Existing randomized controlled trials provide little evidence about safety due to insufficient power and short follow-up; recent observational studies have been inconsistent, but some have associated iron exposure with increased risk of infections and CV events. Given the widespread use and potential safety concerns related to IV iron, well-designed large prospective studies are needed to assess to identify optimal strategies for iron administration that maximize its benefits while avoiding potential risks.

Diagnosing and preventing iron overload

Absolute or functional iron (Fe) deficiency is an important determinant of anemia in hemodialysis patients and parenteral Fe is routinely used to treat this condition in conjunction with erythropoiesis stimulating agents. While restoration of hemoglobin toward the target range is a good outcome of Fe replacement, it is well known that Fe overload and toxicity may be adverse consequences of this therapy. Dialysis clinical practice guidelines recommend tailoring Fe therapy based on transferrin saturation and serum ferritin levels. Unfortunately, serum Fe markers may not accurately reflect the amount of Fe in the body, because factors such as infections, inflammation, or malignancy can alter serum ferritin levels. Some recent trials in dialysis patients receiving high intravenous Fe doses have shown increased cardiovascular morbidity and mortality and studies using magnetic resonance imaging (MRI) in this population have shown excessive tissue liver iron content (LIC) suggesting Fe overload. While LIC measured by MRI correlates well with LIC quantitated by liver biopsy, it only represents a surrogate marker for total body Fe and its clinical relevance in dialysis patients in terms of mortality and morbidity remains to be demonstrated. Nevertheless, these recent findings challenge the use of current serum Fe markers recommended by clinical guidelines to guide safe Fe therapy in dialysis patients. While not yet established for the routine screening of dialysis patients for Fe overload, MRI should be considered in patients who have received a high cumulative dose of intravenous Fe, or have long cumulative dialysis vintage. Further studies are needed to assess how MRI will alter management.

Overview of iron metabolism in health and disease

Iron is an essential element for numerous fundamental biologic processes, but excess iron is toxic. Abnormalities in systemic iron balance are common in patients with chronic kidney disease and iron administration is a mainstay of anemia management in many patients. This review provides an overview of the essential role of iron in biology, the regulation of systemic and cellular iron homeostasis, how imbalances in iron homeostasis contribute to disease, and the implications for chronic kidney disease patients.

Iatrogenic Iron Overload in Dialysis Patients at the Beginning of the 21st Century

Iron overload used to be considered rare in hemodialysis patients but its clinical frequency is now increasingly realized. The liver is the main site of iron storage and the liver iron concentration (LIC) is closely correlated with total iron stores in patients with secondary hemosideroses and genetic hemochromatosis. Magnetic resonance imaging is now the gold standard method for LIC estimation and monitoring in non-renal patients. Studies of LIC in hemodialysis patients by quantitative magnetic resonance imaging and magnetic susceptometry have demonstrated a strong relation between the risk of iron overload and the use of intravenous (IV) iron products prescribed at doses determined by the iron biomarker cutoffs contained in current anemia management guidelines. These findings have challenged the validity of both iron biomarker cutoffs and current clinical guidelines, especially with respect to recommended IV iron doses. Three long-term observational studies have recently suggested that excessive IV iron doses may be associated with an increased risk of cardiovascular events and death in hemodialysis patients. We postulate that iatrogenic iron overload in the era of erythropoiesis-stimulating agents may silently increase complications in dialysis patients without creating frank clinical signs and symptoms. High hepcidin-25 levels were recently linked to fatal and nonfatal cardiovascular events in dialysis patients. It is therefore tempting to postulate that the main pathophysiological pathway leading to these events may involve the pleiotropic master hormone hepcidin (synergized by fibroblast growth factor 23), which regulates iron metabolism. Oxidative stress as a result of IV iron infusions and iron overload, by releasing labile non-transferrin-bound iron, might represent a ‘second hit’ on the vascular bed. Finally, iron deposition in the myocardium of patients with severe iron overload might also play a role in the pathogenesis of sudden death in some patients.

Iron and carbon monoxide attenuate degradation of plasmatic coagulation by Crotalus atrox venom

Hypofibrinogenemia is an important clinical consequence following envenomation by Crotalus species, usually attenuated or prevented by administration of antivenom. It has been determined that iron and carbon monoxide (CO) enhance fibrinogen as a thrombin substrate, likely secondary to conformational changes in molecular structure. We tested the hypothesis that pretreatment of plasma with iron and CO could attenuate the effects of exposure to Crotalus atrox venom. Human plasma was exposed to 0 to 10 μmol/l ferric chloride (iron source) and 0 to 100 μmol/l CO-releasing molecule-2 (CO source) followed by exposure to 0 to 0.5 μg/ml venom for 5 to 20 min. Changes in coagulation kinetics were determined with thrombelastography. Iron and CO significantly attenuated venom-mediated degradation of plasmatic coagulation in terms of onset time, velocity of clot growth and final clot strength. Further preclinical investigation of iron and CO administration as a 'bridge-to-antivenom' to preserve plasmatic coagulation is justified.

Combination with intravenous iron supplementation or doubling erythropoietin dose for patients with chemotherapy-induced anaemia inadequately responsive to initial erythropoietin treatment alone: study protocol for a randomised controlled trial

INTRODUCTION

Erythropoietin (EPO) is a commonly used option in the treatment of chemotherapy-induced anaemia (CIA). However, ∼30-50% of patients fail to achieve an adequate response after initial treatment. Prior studies have demonstrated that intravenous iron might synergistically improve therapeutic response to EPO treatment in this patient population.

METHODS AND ANALYSIS

We will perform this multicentre, randomised, open-label, parallel-group, active controlled non-inferiority study to compare the two combination therapies of EPO plus intravenous iron regimen versus doubling the dose of EPO in patients with CIA who have an inadequate response to initial EPO treatment at a routine dose. A total of 603 patients with an increase in haemoglobin (Hb) <1 g/dL will be enrolled and randomised to one of the three study treatment groups at a 1:1:1 ratio Group 1: EPO treatment at the original dose plus intravenous iron dextran 200 mg every 3 weeks (Q3W) for 15 weeks; Group 2: EPO treatment at the original dose plus intravenous iron dextran 100 mg, twice a week for 5 weeks; Group 3: the control group, doubling the EPO dose without preplanned iron supplementation. The primary outcome measure to compare is the Hb response rate at week 15 and the secondary end points involve therapeutic blood transfusions. Time-to-progression, adverse events and quality of life will also be evaluated.

ETHICS AND DISSEMINATION

All participants will provide informed consent; the study protocol has been approved by the independent ethics committee of Shanghai East Hospital. This study would clearly demonstrate the potential benefit of combining epoetin treatment with intravenous iron supplementation. Findings will be shared with participating hospitals, policymakers and the academic community to promote the clinical management of CIA in China.

TRIAL REGISTRATION NUMBER

NCT02731378.

Intravenous iron administration: new observations and time for the next steps

In this issue of Kidney International, the Dialysis Outcomes and Practice Patterns Study reports that hemodialysis patients with monthly intravenous iron supplementation of 300-399 mg or ⩾400 mg had a 13 or 18% higher risk of dying, respectively, compared with those receiving 100-199 mg per month, with no obvious differences in cause-specific mortalities. This study supports that randomized controlled trials are urgently needed to identify optimized iron supplementation strategies for anemic dialysis patients.

Safety concerns about intravenous iron therapy in patients with chronic kidney disease

Anaemia in chronic kidney disease (CKD) is managed primarily with erythropoiesis-stimulating agents (ESAs) and iron therapy. Following concerns around ESA therapy, intravenous (IV) iron is being administered more and more worldwide. However, it is still unclear whether this approach is safe at very high doses or in the presence of very high ferritin levels. Some observational studies have shown a relationship between either high ferritin level or high iron dose and increased risk of death, cardiovascular events, hospitalization or infection. Others have not been able to confirm these findings. However, they suffer from indication biases. On the other hand, the majority of randomized clinical trials have only a very short follow-up (and thus drug exposure) and are inadequate to assess the mortality risk. None of them have tested the role of different iron doses on hard end points. With the lack of clear evidence coming from well-designed and large-scale studies, several data suggest that excessive iron therapy may be toxic in several aspects, ranging from iron overload to tissue damage from labile iron. A number of experimental and clinical data suggest that either excessive iron therapy or iron overload may be a possible culprit of atherogenesis. The process seems to be mediated by oxidative stress. Iron therapy should also be used cautiously in the presence of active infections, since iron is essential for bacterial growth. Recently, the European Medicines Agency officially raised concerns about rare hypersensitivity reactions following IV iron administration. The balance has been in favour of benefits. In several European countries, this has created a lot of confusion and somewhat slowed the run towards excessive use. Altogether, IV iron remains a mainstay of anaemia treatment in CKD patients. However, in our opinion, its excessive use should be avoided, especially in patients with high ferritin levels and when ESA agents are not contraindicated.

Iron and carbon monoxide prevent degradation of plasmatic coagulation by thrombin-like activity in rattlesnake venom

Thousands suffer poisonous snake bite, often from defibrinogenating species annually. Three rattlesnake species in particular, the timber rattlesnake, Eastern diamondback rattlesnake, and Southern Pacific rattlesnake, cause clinically relevant hypofibrinogenemia via thrombin-like activity in their venom. It has been demonstrated that iron (Fe) and carbon monoxide (CO) change the ultrastructure of plasma thrombi and improve coagulation kinetics. Thus, the present investigation sought to determine if pretreatment of plasma with Fe and CO could attenuate venom-mediated catalysis of fibrinogen via thrombin-like activity. Human plasma was pretreated with ferric chloride (0-10 μM) and CO-releasing molecule-2 (0-100 μM) prior to exposure to 2.5-10 μg/ml of venom obtained from the aforementioned three species of rattlesnake. Coagulation kinetics were determined with thrombelastography. All three snake venoms degraded plasmatic coagulation kinetics to a significant extent, especially diminishing the speed of clot growth and strength. Pretreatment of plasma with Fe and CO completely abrogated the effects of all three venoms on coagulation kinetics. Further in vitro investigation of other pit viper venoms that possess thrombin-like activity is indicated to see if there is significant conservation of venom enzymatic target recognition of specific amino acid sequences such that Fe and CO can reliably attenuate venom-mediated catalysis of fibrinogen. These data also serve as a rationale for future preclinical investigation.

Counterpoint: the treatment decision design

The comparative new-user design is a principled approach to learning about the relative risks and benefits of starting different treatments in patients who have no history of use of the treatments being studied. Vandenbroucke and Pearce (Am J Epidemiol. 2015;182(10):826-833) discuss some problems inherent in incident exposure designs and argue that epidemiology may be harmed by a rigid requirement that follow-up can only begin at first exposure. In the present counterpoint article, a range of problems in pharmacoepidemiology that do not necessarily require that observation begin at first exposure are discussed. For example, among patients who are past or current users of a medication, we might want to know whether treatment should be augmented, switched, restarted, or discontinued. To answer these questions, a generalization of the new-user design, the treatment decision design, which identifies cohorts anchored at times when treatment decisions are being made, such as the evaluation of laboratory parameters, is discussed. The design aims to provide estimates that are directly relevant to physicians and patients, helping them to better understand the risks and benefits of the different treatment choices that they are considering.

Comparative Short-term Safety of Sodium Ferric Gluconate Versus Iron Sucrose in Hemodialysis Patients

BACKGROUND

Despite different pharmacologic properties, little is known about the comparative safety of sodium ferric gluconate versus iron sucrose in hemodialysis patients.

STUDY DESIGN

Retrospective cohort study using the clinical database of a large dialysis provider (2004-2005) merged with administrative data from the US Renal Data System.

SETTING & PARTICIPANTS

66,207 patients with Medicare coverage who received center-based hemodialysis.

PREDICTORS

Iron formulation use assessed during repeated 1-month exposure periods (n=278,357).

OUTCOMES

All-cause mortality, infection-related hospitalizations and mortality, and cardiovascular-related hospitalizations and mortality occurring during a 3-month follow-up period.

MEASUREMENTS

For all outcomes, we estimated 90-day risk differences between the formulations using propensity score weighting of Kaplan-Meier functions, which controlled for a wide range of demographic, clinical, and laboratory variables. Risk differences were also estimated within various clinically important subgroups.

RESULTS

Ferric gluconate was administered in 11.4%; iron sucrose, in 48.9%; and no iron in 39.7% of the periods. Risks for most study outcomes did not differ between ferric gluconate and iron sucrose; however, among patients with a hemodialysis catheter, use of ferric gluconate was associated with a slightly decreased risk for both infection-related death (risk difference, -0.3%; 95% CI, -0.5% to 0.0%) and infection-related hospitalization (risk difference, -1.5%; 95% CI, -2.3% to -0.6%). Bolus dosing was associated with an increase in infection-related events among both ferric gluconate and iron sucrose users.

LIMITATIONS

Residual confounding and outcome measurement error.

CONCLUSIONS

Overall, the 2 iron formulations studied exhibited similar safety profiles; however, ferric gluconate was associated with a slightly decreased risk for infection-related outcomes compared to iron sucrose among patients with a hemodialysis catheter. These associations should be explored further using other data or study designs.

Efficiency of Original versus Generic Intravenous Iron Formulations in Patients on Haemodialysis

AIMS

The appropriate use of intravenous (i.v.) iron is essential to minimise the requirements for erythropoiesis-stimulating agents (ESAs). The clinical efficacy of generic i.v. iron compared to the original formulation is controversial. We evaluated the changes that were induced after switching from a generic i.v. iron to an original formulation in a stable, prevalent haemodialysis (HD) population.

METHODS

A total of 342 patients were included, and the follow-up period was 56 weeks for each formulation. Anaemia parameters and doses of ESA and i.v. iron were prospectively recorded before and after the switch from generic to original i.v. iron.

RESULTS

To maintain the same haemoglobin (Hb) levels after switching from the generic to the original formulation, the requirements for i.v. iron doses were reduced by 34.3% (from 52.8±33.9 to 34.7±31.8 mg/week, p<0.001), and the ESA doses were also decreased by 12.5% (from 30.6±23.6 to 27±21 μg/week, p<0.001). The erythropoietin resistance index declined from 8.4±7.7 to 7.4±6.7 IU/kg/week/g/dl after the switch from the generic to the original drug (p = 0.001). After the switch, the transferrin saturation ratio (TSAT) and serum ferritin levels rose by 6.8% (p<0.001) and 12.4% (p = 0.001), respectively. The mortality rate was similar for both periods.

CONCLUSIONS

The iron and ESA requirements are lower with the original i.v. iron compared to the generic drug. In addition, the uses of the original formulation results in higher ferritin and TSAT levels despite the lower dose of i.v. iron. Further studies are necessary to analyse the adverse effects of higher i.v. iron dosages.

Iron therapy in chronic kidney disease: Recent changes, benefits and risks

Anemia is a common complication in patients with chronic kidney disease (CKD), mainly due to inadequate renal production of erythropoietin. In hemodialysis (HD) patients this condition may be aggravated by iron deficiency (absolute or functional). The correction of this anemia is usually achieved by treatment with erythropoiesis stimulating agents (ESAs) and iron (oral or intravenous). Studies questioning the safety of ESAs (especially at higher doses) changed the pattern of anemia treatment in CKD patients. According to the new guidelines, when transferrin saturation is lower than 30% and ferritin lower than 500 ng/mL, a trial with iron should be started, to avoid therapy with ESAs or at least to reduce the doses needed to treat the anemia. Recent reports showed increasing ferritin levels, towards values above 800 ng/mL, in CKD patients treated according to the guidelines. In this review we focus on the risks of the increased iron use to treat CKD anemia, namely, iron overload and toxicity, increased risk of infections, as well as mortality.

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.

The Labile Side of Iron Supplementation in CKD

The practice of intravenous iron supplementation has grown as nephrologists have gradually moved away from the liberal use of erythropoiesis-stimulating agents as the main treatment for the anemia of CKD. This approach, together with the introduction of large-dose iron preparations, raises the future specter of inadvertent iatrogenic iron toxicity. Concerns have been raised in original studies and reviews about cardiac complications and severe infections that result from long-term intravenous iron supplementation. Regarding the iron preparations specifically, even though all the currently available preparations appear to be relatively safe in the short term, little is known regarding their long-term safety. In this review we summarize current knowledge of iron metabolism with an emphasis on the sources and potentially harmful effects of labile iron, highlight the approaches to identifying labile iron in pharmaceutical preparations and body fluids and its potential toxic role as a pathogenic factor in the complications of CKD, and propose methods for its early detection in at-risk patients.

Iron supplementation and mortality in incident dialysis patients: an observational study

BACKGROUND

Studies on the association between iron supplementation and mortality in dialysis patients are rare and conflicting.

METHODS

In our observational single-center cohort study (INVOR study) we prospectively studied 235 incident dialysis patients. Time-dependent Cox proportional hazards models using all measured laboratory values for up to 7.6 years were applied to study the association between iron supplementation and all-cause mortality, cardiovascular and sepsis-related mortality. Furthermore, the time-dependent association of ferritin levels with mortality in patients with normal C-reactive protein (CRP) levels (<0.5 mg/dL) and elevated CRP levels (≧0.5 mg/dL) was evaluated by using non-linear P-splines to allow flexible modeling of the association.

RESULTS

One hundred and ninety-one (81.3%) patients received intravenous iron, 13 (5.5%) patients oral iron, whereas 31 (13.2%) patients were never supplemented with iron throughout the observation period. Eighty-two (35%) patients died during a median follow-up of 34 months, 38 patients due to cardiovascular events and 21 patients from sepsis. Baseline CRP levels were not different between patients with and without iron supplementation. However, baseline serum ferritin levels were lower in patients receiving iron during follow up (median 93 vs 251 ng/mL, p<0.001). Iron supplementation was associated with a significantly reduced all-cause mortality [HR (95%CI): 0.22 (0.08-0.58); p = 0.002] and a reduced cardiovascular and sepsis-related mortality [HR (95%CI): 0.31 (0.09-1.04); p = 0.06]. Increasing ferritin concentrations in patients with normal CRP were associated with a decreasing mortality, whereas in patients with elevated CRP values ferritin levels>800 ng/mL were linked with increased mortality.

CONCLUSIONS

Iron supplementation is associated with reduced all-cause mortality in incident dialysis patients. While serum ferritin levels up to 800 ng/mL appear to be safe, higher ferritin levels are associated with increased mortality in the setting of concomitant inflammation.

Intravenous iron exposure and mortality in patients on hemodialysis

BACKGROUND AND OBJECTIVES

Clinical trials assessing effects of larger cumulative iron exposure with outcomes are lacking, and observational studies have been limited by assessment of short-term exposure only and/or failure to assess cause-specific mortality. The associations between short- and long-term iron exposure on all-cause and cause-specific mortality were examined.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The study included 14,078 United States patients on dialysis initiating dialysis between 2003 and 2008. Intravenous iron dose accumulations over 1-, 3-, and 6-month rolling windows were related to all-cause, cardiovascular, and infection-related mortality in Cox proportional hazards models that used marginal structural modeling to control for time-dependent confounding.

RESULTS

Patients in the 1-month model cohort (n=14,078) were followed a median of 19 months, during which there were 27.6% all-cause deaths, 13.5% cardiovascular deaths, and 3% infection-related deaths. A reduced risk of all-cause mortality with receipt of >150-350 (hazard ratio, 0.78; 95% confidence interval, 0.64 to 0.95) or >350 mg (hazard ratio, 0.79; 95% confidence interval, 0.62 to 0.99) intravenous iron compared with >0-150 mg over 1 month was observed. There was no relation of 1-month intravenous iron dose with cardiovascular or infection-related mortality and no relation of 3- or 6-month cumulative intravenous iron dose with all-cause or cardiovascular mortality. There was a nonstatistically significant increase in infection-related mortality with receipt of >1050 mg intravenous iron in 3 months (hazard ratio, 1.69; 95% confidence interval, 0.87 to 3.28) and >2100 mg in 6 months (hazard ratio, 1.59; 95% confidence interval, 0.73 to 3.46).

CONCLUSIONS

Among patients on incident dialysis, receipt of ≤ 1050 mg intravenous iron in 3 months or 2100 mg in 6 months was not associated with all-cause, cardiovascular, or infection-related mortality. However, nonstatistically significant findings suggested the possibility of infection-related mortality with receipt of >1050 mg in 3 months or >2100 mg in 6 months. Randomized clinical trials are needed to assess the safety of exposure to greater cumulative intravenous iron doses.

Comparative short-term safety of bolus versus maintenance iron dosing in hemodialysis patients: a replication study

Background

Recent research has reported that patients receiving bolus (frequent large doses to achieve iron repletion) versus maintenance dosing of iron have an increased short-term risk of infection, but a similar risk of cardiovascular events. We sought to determine whether these findings could be replicated using the same methods and a different data source.

Methods

Clinical data from 6,605 patients of a small U.S. dialysis provider merged with Medicare claims data were examined. Iron dosing patterns (bolus, maintenance, no iron) were identified during 1-month exposure periods and cardiovascular and infection-related outcomes were assessed during 3-month follow-up periods. The effects of bolus versus maintenance dosing were assessed using Cox proportional hazards regression analyses to estimate hazard ratios and semiparametric additive risk models to estimate hazard rate differences, controlling for demographic and clinical characteristics, laboratory values and medications, and comorbidities.

Results

48,050 exposure/follow-up periods were examined. 13.9 percent of the exposure periods were bolus dosing, 49.3 percent were maintenance dosing, and the remainder were no iron use. All of the adjusted hazard ratios were >1.00 for the infection-related outcomes, suggesting that bolus dosing increases the risk of these events. The effects were greatest for hospitalized for infection of any major organ system (hazard ratio 1.13 (1.03, 1.24)) and use of intravenous antibiotics (hazard ratio 1.08 (1.02, 1.15). When examining the subgroup of individuals with catheters, the hazard ratios for the infection-related outcomes were generally greater than in the overall sample. There was little association between type of dosing practice and cardiovascular outcomes.

Conclusions

Results of this study provide further evidence of the association between bolus dosing and increased infection risk, particularly in the subgroup of patients with a catheter, and of the lack of an association between dosing practices and cardiovascular outcomes.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2369-15-154) contains supplementary material, which is available to authorized users.