Erythropoietin dosing in children with chronic kidney disease: based on body size or on hemoglobin deficit?

Real-world evidence on the dosing and safety of C.E.R.A. in pediatric dialysis patients: findings from the International Pediatric Dialysis Network registries

BACKGROUND

This retrospective real-world study used data from two registries, International Pediatric Peritoneal Dialysis Network (IPPN) and International Pediatric Hemodialysis Network (IPHN), to characterize the efficacy and safety of continuous erythropoietin receptor activator (C.E.R.A.) in pediatric patients with chronic kidney disease (CKD) on peritoneal dialysis (PD) or hemodialysis (HD).

METHODS

IPPN and IPHN collect prospective data (baseline and every 6 months) from pediatric PD and HD centers worldwide. Demographics, clinical characteristics, dialysis information, treatment, laboratory parameters, number and causes of hospitalization events, and deaths were extracted for patients on C.E.R.A. treatment (IPPN: 2007-2021; IPHN: 2013-2021).

RESULTS

We analyzed 177 patients on PD (median age 10.6 years) and 52 patients on HD (median age 14.1 years) who had ≥ 1 observation while being treated with C.E.R.A. The median (interquartile range [IQR]) observation time under C.E.R.A. exposure was 6 (0-12.5) and 12 (0-18) months, respectively. Hemoglobin concentrations were stable over time; respective means (standard deviation) at last observation were 10.9 (1.7) g/dL and 10.4 (1.7) g/dL. Respective median (IQR) monthly C.E.R.A. doses at last observation were 3.5 (2.3-5.1) µg/kg, or 95 (62-145) µg/m2 and 2.1 (1.2-3.4) µg/kg, or 63 (40-98) µg/m2. Non-elective hospitalizations occurred in 102 (58%) PD and 32 (62%) HD patients. Seven deaths occurred (19.8 deaths per 1000 observation years).

CONCLUSIONS

C.E.R.A. was associated with efficient maintenance of hemoglobin concentrations in pediatric patients with CKD on dialysis, and appeared to have a favorable safety profile. The current analysis revealed no safety signals.

Anemia in chronic kidney disease

Anemia is common and associated with adverse outcomes in children with chronic kidney disease (CKD). Many factors contribute to declining hemoglobin as CKD progresses, but impaired production of erythropoietin by failing kidneys is a central cause. Hepcidin-mediated iron restriction also contributes to anemia by downregulating both intestinal iron absorption and release of stored iron for erythropoiesis. The core components of anemia management remain erythropoiesis-stimulating agents (ESA) and iron supplementation, but despite these therapies, a substantial number of children remain anemic. Although escalating ESA dose to target higher hemoglobin has been associated with adverse outcomes in adults, no trials have investigated this association in children, and maintaining hemoglobin levels in a narrow range with conservative ESA dosing is challenging. Judicious use of iron supplementation can enhance the response to ESAs, but the iron storage markers most commonly used in clinical practice have limitations in distinguishing which patients will benefit most from additional iron. Several novel anemia therapies, including hypoxia-inducible factor stabilizers, prolyl hydroxylase inhibitors, and dialysate-delivered iron supplements, have been developed and may offer options for alternative anemia management. However, the safety and efficacy of these agents in children with CKD has yet to be assessed.

Chronic kidney disease in children

Chronic kidney disease (CKD) is a major health problem worldwide. Although relatively uncommon in children, it can be a devastating illness with many long-term consequences. CKD presents unique features in childhood and may be considered, at least in part, as a stand-alone nosologic entity. Moreover, some typical features of paediatric CKD, such as the disease aetiology or cardiovascular complications, will not only influence the child's health, but also have long-term impact on the life of the adult that they will become. In this review we will focus on the unique issues of paediatric CKD, in terms of aetiology, clinical features and treatment. In addition, we will discuss factors related to CKD that start during childhood and require appropriate treatments in order to optimize health outcomes and transition to nephrologist management in adult life.

Association of higher erythropoiesis stimulating agent dose and mortality in children on dialysis

BACKGROUND

Higher doses of erythropoiesis-stimulating agents (ESA) have been associated with an increased risk of adverse outcomes in adults with chronic kidney disease (CKD) and end-stage kidney disease (ESRD), but to our knowledge no trials have been performed in children. We examined the association between ESA dose and all-cause mortality in a prevalent pediatric dialysis population.

METHODS

Retrospective cohort study utilizing national data on all prevalent dialysis patients aged <18 years from the Centers for Medicare and Medicaid Services' 2005 ESRD Clinical Performance Measures (CPM) project, linked to 18-month mortality records from the United States Renal Data System. Multivariate Cox proportional hazards regression was performed to determine the risk of mortality by mean weekly ESA dose.

RESULTS

Eight-hundred and twenty-nine children were included in the analysis; 7 % died during follow-up. A higher proportion of patients receiving ESA doses in the highest category (erythropoietin ≥350 units/kg/week or darbepoetin ≥1.5 units/kg/week) died (50 % vs 28 %, p = 0.002), and also demonstrated a trend toward lower hemoglobin (11.0 vs 11.4 g/dL, p = 0.05). In multivariate analysis, patients receiving the highest dose of ESA demonstrated an increased risk of mortality (hazard ratio 3.37; p value <0.01).

CONCLUSION

Higher ESA dose is independently associated with mortality in children on chronic dialysis.

Management of anemia with erythropoietic-stimulating agents in children with chronic kidney disease

Anemia management is an important component of the care provided to children with chronic kidney disease (CKD) and influences both morbidity and mortality risk. The introduction of recombinant human erythropoietin to the treatment regimen three decades ago revolutionized the therapy and significantly decreased the need for repeated blood transfusions and exposure to associated risks. Recent data on the efficacy and complications associated with erythropoietic-stimulating agent (ESA) usage has, however, prompted a reassessment of treatment-related recommendations. This review will address these recommendations, in addition to describing pediatric outcomes associated with current ESAs and presenting information on alternative ESAs, many of which will likely soon be incorporated into clinical practice.

Prevalence and predictors of the sub-target Hb level in children on dialysis

BACKGROUND

Anaemia is a common and potentially treatable co-morbidity of end-stage renal disease. We aimed to determine the prevalence of the sub-target haemoglobin (Hb) level among European children on dialysis and to identify factors associated with a low Hb level.

METHODS

From the European Society for Paediatric Nephrology (ESPN)/European Renal Association-European Dialysis Transplant Association (ERA-EDTA) registry, data were available on 2351 children between 1 month and 18 years of age, totalling 5546 measurements from 19 countries.

RESULTS

The mean Hb level was 10.8 g/dL (5th-95th percentiles, 7.4-13.9). Among those above 2 years of age, the mean Hb level was 10.9 g/dL (11.4% below 8.5 g/dL), while it was 10.3 g/dL among those below 2 years (11.2% below 8.0 g/dL). A total of 91.2% of the patients were on an erythropoiesis-stimulating agent (ESA). Hb levels increased with age and were higher in peritoneal dialysis compared with haemodialysis patients. Patients with congenital anomalies of the kidney and urinary tract showed the highest Hb levels, and those with cystic kidney diseases or metabolic disorders the lowest ones. Ferritin levels between 25 and 50 ng/mL were associated with the highest Hb levels. We found a weak inverse association between parathyroid hormone (PTH) and Hb. Whereas standardized blood pressure (BP) was not elevated in patients with above-target Hb, elevated systolic BP z-score was noted in those with sub-target Hb levels.

CONCLUSIONS

Sub-target Hb levels remain common in children on dialysis, in spite of virtually all children being treated with ESA; although we cannot exclude under-dosing. Optimal ferritin levels seemed to be slightly lower in children (25-50 ng/mL) than those in adults. Other risk factors for sub-target Hb are dialysis modality and a high PTH level.

Anaemia treatment in chronically dialysed children: a multicentre nationwide observational study

OBJECTIVE

Erythropoiesis-stimulating agents (ESAs) are applied as a standard therapy in children with anaemia in chronic kidney disease. The aim of this study was to describe the efficacy and details of ESA treatment in a population of dialysed children in Poland.

MATERIAL AND METHODS

The study had a prospective observational design and was performed in 12 dialysis centres. The study group comprised 117 dialysed children with a mean age at enrolment of 165.33 (97.18-196.45) months.

RESULTS

Dialysed children were treated mostly with epoietin beta and darbepoietin. The mean dose of ESA was 99 (68-147) U/kg/week with a significant difference between patients on peritoneal dialysis [83 (54-115)] and haemodialysis [134 (103-186)] (p < 0.0001). The mean haemoglobin of all the time-point tests during 6 months was 10.91 ± 1.18 g/dl. The efficacy of anaemia treatment was unsatisfactory in 52% of subjects. In multivariate analysis, initial haemoglobin level <10 g/l, any infection, younger age at first dialysis, malnutrition and inadequate ESA dosage remained significant predictors of anaemia.

CONCLUSIONS

The study revealed that anaemia treatment in Polish children is unsatisfactory. Late commencement of the treatment, inadequate dosing, malnutrition and infections could constitute risk factors for therapy failure.

Resistance to erythropoietin-stimulating agents: etiology, evaluation, and therapeutic considerations

Routine clinical and laboratory assessments facilitate diagnosis of erythropoietin (EPO) resistant anemia by allowing early identification of patients with non-adherence. Any new event that impairs response to EPO (e.g., catheter sepsis) must be promptly controlled. Because of the confounding interaction of its risk factors, initial evaluation should include nutrition, dialysis adequacy, hemorrhage, bone mineral metabolism, and inflammation. Prevention of EPO resistance is more cost effective and should include adequate dialysis and nutritional supplements. Blood loss during hemodialysis (HD) procedures should be minimized. If there is laboratory proof of iron deficit intravenous repletion is most effective. Oxidative stress may be attenuated by vitamins E and C, while optimal control of hyperparathyroidism will enhance EPO stimulation. Contaminated dialysates should be suspected if there is EPO-stimulating agents (ESA) resistance at the same time among most members of a dialysis program. Heavy metal toxicity should be suspected in high-risk patients. The impact of co-morbidities such as hemoglobinopathy, glucose 6 phosphate dehydrogenase (G6PD) deficiency and connective tissue diseases must be excluded in an appropriate setting. In conclusion, given the multiple risk factors of EPO resistance promotion of the overall health status will most likely yield an enduring benefit. Finally, there are experimental trials of gene-based (therapy) to stimulate endogenous EPO synthesis with the goal of avoiding the off-target effect of excessive dosing.

Red blood cell transfusions in children awaiting heart transplantation

In children awaiting heart transplantation, the benefits of RBC transfusion must be weighed against the potential risks of allosensitization. We sought to describe the use of RBC transfusion and erythropoietin in children with heart failure, as well as assess the impact of these measures on allosensitization. Hospitalized patients listed for heart transplantation between 1/03 and 12/10 were included in the analysis. We excluded patients supported by mechanical support or those highly sensitized prior to listing. Sixty-seven subjects (median age of 6.2 yr) met inclusion criteria. The mean waitlist time was 19.5 days. The majority of subjects, 50 (75%), received at least one RBC transfusion while listed. For those who were transfused, the median number of RBC transfusion events was 3, range: 1-8. Erythropoietin was given to 37 (55%) of subjects. Erythropoietin administration was not associated with subsequent need for transfusion (p = 0.61). Of the 50 subjects who received RBC transfusion, none developed significant elevation of serum PRA by the time of transplant. RBC transfusion may be commonly undertaken in hospitalized children awaiting transplantation. The likelihood of allosensitization following leukoreduced RBC transfusion is extremely low. The benefits of routine erythropoietin administration to reduce the need for transfusion remain to be determined.

Anemia in children with chronic kidney disease

Anemia is a common comorbidity in children with chronic kidney disease (CKD). This condition is associated with multiple adverse clinical consequences and its management is a core component of nephrology care. Increased morbidity and mortality, increased risk of cardiovascular disease and decreased quality of life have been associated with anemia of CKD in children. Although numerous complex factors interact in the development of this anemia, erythropoietin deficiency and iron dysregulation (including iron deficiency and iron-restricted erythropoiesis) are the primary causes. In addition to iron supplementation, erythropoietin-stimulating agents (ESAs) can effectively treat this anemia, but there are important differences in ESA dose requirements between children and adults. Also, hyporesponsiveness to ESA therapy is a common problem in children with CKD. Although escalating ESA doses to target increased hemoglobin values in adults has been associated with adverse outcomes, no studies have demonstrated this association in children. The question of appropriate target hemoglobin levels in children, and the approach by which to achieve these levels, remains under debate. Randomized, controlled studies are needed to evaluate whether normalization of hemoglobin concentrations is beneficial to children, and whether this practice is associated with increased risks.

No difference in meeting hemoglobin and albumin targets for dialyzed children with urologic disorders

Urologic disorders are the most common cause of chronic kidney disease in children. To determine whether children with urologic etiology of end-stage renal disease (ESRD) fare better than children with ESRD from other causes while on dialysis, we conducted a cross-sectional study of children <18 years receiving peritoneal and hemodialysis in the United States using data from the Centers for Medicare & Medicaid Services 2005 ESRD CPM Project. We compared baseline demographics and the study groups. In multivariate logistic regression analysis of 1,286 subjects, we assessed whether children with urologic disorders had a higher odds of meeting adult KDOQI targets for hemoglobin levels ≥11 g/dl and albumin ≥3.5 BCG/3.2 BCP g/dl. We conducted a subset analysis of 1,136 patients to examine the impact of erythropoietin on hemoglobin targets. Our results did not reveal differences in achievement of adult hemoglobin targets (adjusted OR: 1.27; p value 0.09; CI: 0.97-1.66) or in the subset analysis with erythropoietin (adjusted OR: 1.32; p value 0.06; CI: 0.98-1.78) or albumin targets (adjusted OR: 1.22; p value 0.21; CI: 0.90-1.65) in adjusted analyses. Due to our study's limitations, it is difficult to determine whether this may result from treatment prior to dialysis initiation or treatment effect of dialysis rather than underlying diagnosis.

Risk for anemia in pediatric chronic kidney disease patients: a report of NAPRTCS

Previous studies in children with chronic kidney disease (CKD) have identified low hemoglobin as a risk factor for poor outcomes. A retrospective review of the North American Pediatric Renal Trials and Collaborative Studies (NAPRTCS) CKD registry was performed to identify the prevalence of and risk factors for anemia among children with stage 3 CKD, including both patients with low hemoglobin and those whose hemoglobin normalized with an erythropoiesis-stimulating agent (ESA). At enrollment, 2,792 patients had stage 3 CKD. Mean age was 9.5 (+/-0.11) years, 62.1% were male, 61.3% were white, and 43.7% had structural/urologic disease. Among 1,640 of those patients with 12 month follow-up data available for multivariate analysis, 73% met the criteria for anemia. Multivariate logistic regression analysis identifying risk factors for anemia at the 12-month follow-up revealed that, after controlling for estimated glomerular filtration rate, age >2 years, male sex, earlier era of study entry, and prescription of anti-hypertensive medications are associated with an increased risk for anemia at 12 months. In addition, multivariate Cox proportional hazards regression analysis revealed that when patients with ESA-corrected hemoglobin are included in the definition, anemia is not associated with increased risk of progression to end stage renal disease (dialysis initiation or transplantation).

Target hemoglobin trials in chronic kidney disease: design and interpretation issues

Optimal management of anemia in patients with chronic kidney disease remains a divisive issue within the nephrology community. Because the evidence provided by successive randomized controlled trials has often proven to be incongruent, it is natural to consider whether methodological issues may be responsible. Using four large trials [US Normal Hematocrit, Canadian European Normalization of Hemoglobin, Cardiovascular Risk Reduction by Early Anemia Treatment with Epoetin Beta (CREATE) and Correction of Hemoglobin and Outcomes in Renal Insufficiency (CHOIR)], this review article highlights several methodological issues that may be important when trial evidence is translated into clinical practice. Issues discussed include heterogeneity of enrollment criteria, failure to conceal treatment allocation, generalizability of study interventions, systematic use of imbalanced co-interventions [especially dose of erythropoietin stimulating agent (ESA), confusion regarding stopping rules and interim analyses and failure to account for imbalances in important patient characteristics generated at randomization.