Anemia in conventional hemodialysis: Finding the optimal treatment balance

Relation between erythropoietin resistance and metabolic syndrome in hemodialysis patients: A multicentric propensity score matched analysis

Erythropoietin (EPO) resistance is frequently reported in hemodialysis (HD) patients. Metabolic syndrome (MetS) is a common biochemical condition that comprises central obesity, dyslipidemia, hypertension, and hyperglycemia. The present study aimed to assess the relation between MetS and EPO resistance in HD patients. The present multicentric study included 150 patients with EPO resistance and 150 patients without EPO resistance. Short-acting EPO resistance was diagnosed if the erythropoietin resistance index is ≥1.0 IU/kg/gHb. Comparison between patients with EPO resistance and patients without resistance revealed that the former group had significantly higher body mass index, lower hemoglobin levels, lower albumin levels, higher ferritin levels, and higher high-sensitivity C-reactive protein (hsCRP) levels. In addition, patients in the EPO resistance group had significantly higher frequency of MetS (75.3% vs 38.0%, p < 0.001) and higher number of MetS components (2.7 ± 1.3 vs 1.8 ± 1.6, p < 0.001). Multivariate logistic regression analysis identified lower albumin levels (OR (95% CI): 0.072 (0.016-0.313), p < 0.001), higher ferritin levels (OR (95% CI): 1.05 (1.033-1.066), p< 0.001), higher hsCRP levels (OR (95% CI): 1.041 (1.007-1.077), p = 0.018), and MetS (OR (95% CI): 36.68 (2.893-465.05), p = 0.005) as predictors of EPO resistance in the studied patients. The present study identified MetS as a predictor of EPO resistance in HD patients. Other predictors include serum ferritin, hsCRP, and albumin levels.

Market Consolidation and Innovation in US Dialysis

While patients with end-stage kidney disease have benefited from innovations in clinical therapeutics and care delivery, these changes have been primarily incremental and have not fundamentally transformed care delivery. Dialysis markets are highly concentrated, which may impede innovation. Unique features of the dialysis industry that have contributed to consolidation can help to explain links between consolidation and innovation. We discuss these unique features and then provide a framework for considering the effects of consolidation on innovation in dialysis that focuses on the following economic considerations: (1) industry characteristics, composition, and stage of consolidation, (2) innovation characteristics and relative profitability, (3) the role of government regulation, and (4) innovation from smaller providers and new entrants. We present examples of how these considerations have influenced the adoption of alternative dialysis technologies such as peritoneal dialysis and erythropoietin-stimulating agents, and we discuss how consolidated markets can both help and hinder recent policy initiatives to transform dialysis care delivery. Only by considering these important drivers of consolidation, future efforts can be successful in transforming end-stage kidney disease care.

JTZ-951 (enarodustat), a hypoxia-inducible factor prolyl hydroxylase inhibitor, improves iron utilization and anemia of inflammation: Comparative study against recombinant erythropoietin in rat

Anemia with inflammation-induced defective iron utilization is a pathological condition observed in patients suffering from chronic kidney disease (CKD) or chronic inflammatory disease. There is no reasonable treatment for these conditions, because the effects of erythropoiesis stimulating agents (ESAs) or iron supplementation in the treatment of anemia are insufficient. JTZ-951 (enarodustat) has been characterized as a novel, orally bioavailable inhibitor of hypoxia-inducible factor prolyl hydroxylase (HIF-PH), and has been developed as a novel therapeutic agent for anemia with CKD. In this study, the effects of JTZ-951 on iron utilization during erythropoiesis and on anemia of inflammation were compared with those of recombinant human erythropoietin (rHuEPO) using normal rat and rat model of anemia of inflammation. In normal rats, under conditions in which JTZ-951 and rHuEPO showed similar erythropoietic effect, repeated doses of JTZ-951 induced erythropoiesis while retaining the hemoglobin content in red blood cells, while administration of rHuEPO resulted in decrease in some erythrocyte-related parameters. As for iron-related parameters during erythropoiesis, JTZ-951 exhibited more efficient iron utilization compared to rHuEPO. A single dose of JTZ-951 resulted in decrease in hepcidin expression observed within 24 h after administration, but a single dose of rHuEPO did not. In a rat model of anemia of inflammation (also known as a model with functional iron-deficiency), JTZ-951 showed erythropoietic effect, in contrast with rHuEPO. These results suggest that, unlike rHuEPO, JTZ-951 stimulates erythropoiesis by increasing iron utilization, and improves anemia of inflammation.

Association between Dipeptidyl Peptidase-4 Inhibitor Prescription and Erythropoiesis-Stimulating Agent Hyporesponsiveness in Hemodialysis Patients with Diabetes Mellitus

INTRODUCTION

Dipeptidyl peptidase-4 (DPP-4) has been hypothesized to improve responsiveness to erythropoiesis-stimulating agent (ESA). We aimed to describe the trend in DPP-4 inhibitor prescription patterns and assess the association between DPP-4 inhibitor prescription and ESA hyporesponsiveness (eHypo) in Japanese hemodialysis (HD) patients with diabetes mellitus (DM).

METHODS

We analyzed data from the Japan Dialysis Outcomes and Practice Patterns Study phase 4-6 (2009-2017) on patients with DM who underwent HD thrice per week for at least 4 months. The primary exposure of interest was having a DPP-4 inhibitor prescription. The primary analysis outcomes were a binary indicator of eHypo (mean hemoglobin <10 and mean ESA dose >6,000 units/week over 4 months) and the natural log-transformed ESA resistance index (ERI). We used conditional logistic regression to compare within-patient changes in eHypo before and after initial DPP-4 inhibitor prescription. We used linear generalized estimating equation models to compare continuous ERI outcomes while accounting for within-patient repeated measurements with an exchangeable correlation structure.

RESULTS

There was a monotonic increase in DPP-4 inhibitor prescription according to study year up to 20% in 2017. Moreover, 12.8% of patients with a DPP-4 inhibitor prescription were ESA hyporesponsive before the initial DPP-4 inhibitor prescription. After DPP-4 inhibitor prescription, the odds of eHypo and mean log-ERI remained unchanged in the whole cohort of our study. The interaction analysis of DPP-4 inhibitor and sideropenia showed that DPP-4 inhibitors attenuated eHypo in the patients without iron deficiency.

CONCLUSION

Our findings indicate a recent increase in DPP-4 inhibitor prescription among Japanese HD patients with DM. DPP-4 inhibitors could improve ERI in patients undergoing HD without iron deficiency.

Anemia management for home dialysis including the new US public policy initiative

Patients with end-stage kidney disease (ESKD) requiring kidney replacement therapy are often treated in conventional dialysis centers at substantial cost and patient inconvenience. The recent United States Executive Order on Advancing American Kidney Health, in addition to focusing on ESKD prevention and reforming the kidney transplantation system, focuses on providing financial incentives to promote a shift toward home dialysis. In accordance with this order, a goal was set to have 80% of incident dialysis patients receiving home dialysis or a kidney transplant by 2025. Compared with conventional in-center therapy, home dialysis modalities, including both home hemodialysis and peritoneal dialysis, appear to offer equivalent or improved mortality, clinical outcomes, hospitalization rates, and quality of life in patients with ESKD in addition to greater convenience, flexibility, and cost-effectiveness. Treatment of anemia, a common complication of chronic kidney disease, may be easier to manage at home with a new class of agents, hypoxia-inducible factor-prolyl hydroxylase inhibitors, which are orally administered in contrast to the current standard of care of i.v. iron and/or erythropoiesis-stimulating agents. This review evaluates the clinical, quality-of-life, economic, and social aspects of dialysis modalities in patients with ESKD, including during the coronavirus disease 2019 pandemic; explores new therapeutics for the management of anemia in chronic kidney disease; and highlights how the proposed changes in Advancing American Kidney Health provide an opportunity to improve kidney health in the United States.

Achieving dialysis adequacy: A global perspective

Dialysis adequacy is conventionally quantified as net urea clearance. Single pool (sp) Kt/V_urea remains the best studied measure of dialysis adequacy globally. Other measures such as fluid status control, anemia correction, and mineral metabolism are monitored variably. Increasing use of hemodiafiltration across Europe and many parts of Japan and Australia is predicated on studies showing better patient survival with middle molecule clearance. Apart from local clinical practice guidelines, the income level and public health policy of a country determine quality of dialysis services. Among developed nations, small solute clearance adequacy targets are achieved with high frequency. In the United States, dialysis adequacy target is met by focussing on high blood flow rates and large dialyzer size, sometimes at the cost of session time. In Japan, Australia, and Germany, session length is given importance. Dialysis adequacy reporting is restricted and inconsistent in developing nations. The Gulf Cooperation Council countries, Russia and Malaysia, respectively, are close to achieving dialysis adequacy target (spKt/V_urea ≥1.2) universally in their dialysis populations. Patient-reported outcomes are typically measured only in developed countries. Patient survival on dialysis, partly linked to dialysis adequacy, varies greatly around the world, with Japan having the best survival rates. Until the development of better markers of dialysis adequacy, universal consistency in reporting of conventional parameters with a focus on patient-reported measures should be endeavored.

Biomarkers of iron metabolism in chronic kidney disease

Iron is the most abundant transition metal in the human body and an essential element required for growth and survival. Our understanding of the molecular control of iron metabolism has increased dramatically over the past 20 years due to the discovery of hepcidin, which regulates the uptake of dietary iron and its mobilization from macrophages and hepatic stores. Anemia and iron deficiency are common in chronic kidney disease. The pathogenesis of anemia of chronic kidney disease is multifactorial. Correction of anemia requires two main treatment strategies: increased stimulation of erythropoiesis, and maintenance of an adequate iron supply to the bone marrow. However, there are still many uncertainties in regard to iron metabolism in patients with chronic kidney disease and in renal replacement therapy. The aim of this review was to summarize the current knowledge on iron metabolism in this population, including new biomarkers of iron status. There is an area of uncertainty regarding diagnostic utility of both erythroferrone (ERFE) and hepcidin in end-stage renal disease (ESRD) patients. Higher concentration of hepcidin in oligoanuric patients may reflect decreased renal clearance. Furthermore, the hepcidin-lowering effect of ERFE in ESRD patients treated with erythropoiesis-stimulating agents (ESAs) may be blunted by underlying inflammation and concomitant iron treatment. Thus, future studies should validate the use of ERFE as a biomarker of erythropoiesis and predictor of response to iron and ESA therapy in dialysis-dependent patients.

The Many Facets of Erythropoietin Physiologic and Metabolic Response

In mammals, erythropoietin (EPO), produced in the kidney, is essential for bone marrow erythropoiesis, and hypoxia induction of EPO production provides for the important erythropoietic response to ischemic stress, such as during blood loss and at high altitude. Erythropoietin acts by binding to its cell surface receptor which is expressed at the highest level on erythroid progenitor cells to promote cell survival, proliferation, and differentiation in production of mature red blood cells. In addition to bone marrow erythropoiesis, EPO causes multi-tissue responses associated with erythropoietin receptor (EPOR) expression in non-erythroid cells such neural cells, endothelial cells, and skeletal muscle myoblasts. Animal and cell models of ischemic stress have been useful in elucidating the potential benefit of EPO affecting maintenance and repair of several non-hematopoietic organs including brain, heart and skeletal muscle. Metabolic and glucose homeostasis are affected by endogenous EPO and erythropoietin administration affect, in part via EPOR expression in white adipose tissue. In diet-induced obese mice, EPO is protective for white adipose tissue inflammation and gives rise to a gender specific response in weight control associated with white fat mass accumulation. Erythropoietin regulation of fat mass is masked in female mice due to estrogen production. EPOR is also expressed in bone marrow stromal cells (BMSC) and EPO administration in mice results in reduced bone independent of the increase in hematocrit. Concomitant reduction in bone marrow adipocytes and bone morphogenic protein suggests that high EPO inhibits adipogenesis and osteogenesis. These multi-tissue responses underscore the pleiotropic potential of the EPO response and may contribute to various physiological manifestations accompanying anemia or ischemic response and pharmacological uses of EPO.