Medium cut-off dialyzers in a large population of hemodialysis patients in Colombia: COREXH registry

Expanded hemodialysis: a new concept of renal replacement therapy

Expanded hemodialysis (HDx) is an innovation that can increase the effectiveness of hemodialysis. The dialysis process is expected to promote more uremic toxins removal without causing significant hypoalbuminemia using the medium cut-off (MCO) membrane or also known as the high retention onset membrane. Compared with conventional membranes such as those of low-flux hemodialysis, high-flux hemodialysis, and hemodiafiltration, the MCO membrane in HDx is considered to be the closest to the physiology of the glomerular membrane. Several studies have shown the use of the MCO membrane in HDx provides clinical benefits and better outcome although further studies are needed to assess the long-term effect and greater impact for dialysis patients.

Use of regional citrate anticoagulation with medium cut-off membrane: pilot report

Background

Regional citrate anticoagulation during hemodialysis provides an immediate and complete anticoagulant effect, which is limited to the extracorporeal circuit. Citrate has become the standard anticoagulant in acute renal replacement therapy and is widely used in various intermittent hemodialysis modalities, especially for patients with contraindications for heparin. With the increased adoption of medium cut-off membranes, experience with regional citrate anticoagulation is needed. To our knowledge, this is the first report to assess the feasibility of regional citrate anticoagulation in expanded hemodialysis.

Methods

We prospectively analyzed 5 expanded hemodialysis procedures in 5 patients in which a medium cut-off membrane (Theranova®) was used. We followed our standard citrate protocol developed and tested for high-flux membrane. Anticoagulation was performed with a continuous infusion of 8% trisodium citrate into the arterial line and supplementation of 1 M calcium chloride into the venous line. We monitored ionized calcium and magnesium, sodium and blood gas analysis. Anticoagulation effectiveness was assessed by post-filter ionized calcium and by visual inspection of the anticoagulation in the circuit.

Results

There were no prematurely terminated procedures due to anticoagulation-related complications. With a blood flow of 250 mL/min and a dialysate flow of 500 mL/min, we were able to maintain serum ionized calcium in the range of 0.89–1.29 mmol/L and serum sodium in the range of 136–144 mmol/L. The mean pre- and post-dialysis arterial circuit pH was 7.42 (± 0.04) and 7.53 (± 0.23), respectively. The mean pre- and post-dialysis serum ionized magnesium was 0.54 (± 0.04) mmol/L and 0.43 (± 0.03) mmol/L, respectively (measurements were done on a point-of-care ionometer with a lower normal range for ionized magnesium).

Conclusion

We have shown that our standard citrate protocol for high-flux hemodialysis membrane could be successfully adopted for use in expanded hemodialysis with a medium cut-off membrane. Overall, electrolyte and acid-base balances were relatively well-controlled and anticoagulation effectiveness was excellent.

Trial registration

This is a pilot report with results taken from a larger ongoing trial (registered at ClinicalTrials.gov on October 25, 2019 under number NCT04139525) comparing citrate and heparin anticoagulation during expanded hemodialysis.

Hemodiafiltration (HDF) versus expanded hemodialysis (HDx)

Medium cutoff (MCO) membranes have resulted in a novel dialyzer class designed to improve membrane permeability and have been postulated as an alternative to online hemodiafiltration since MCO membranes may achieve similar solute clearances. These membranes have been incorporated into clinical practice, and the term expanded HD (HDx) has been proposed to differentiate from high-flux hemodialysis. Efficacy, safety, and quality of life comparison of HDF versus HDx have been reviewed in this article.

Effects of Expanded Hemodialysis with Medium Cut-Off Membranes on Maintenance Hemodialysis Patients: A Review

Kidney failure is associated with high morbidity and mortality. Hemodialysis, the most prevalent modality of renal replacement therapy, uses the principle of semipermeable membranes to remove solutes and water in the plasma of patients with kidney failure. With the evolution of hemodialysis technology over the last half century, the clearance of small water-soluble molecules in such patients is adequate. However, middle molecules uremic toxins are still retained in the plasma and cause cardiovascular events, anemia, and malnutrition, which significantly contribute to poor quality of life and high mortality in maintenance hemodialysis patients. A new class of membrane, defined as a medium cut-off (MCO) membrane, has emerged in recent years. Expanded hemodialysis with MCO membranes is now recognized as the artificial kidney model closest to natural kidney physiology. This review summarizes the unique morphological characteristics and internal filtration–backfiltration mechanism of MCO membranes, and describes their effects on removing uremic toxins, alleviating inflammation and cardiovascular risk, and improving quality of life in maintenance hemodialysis patients.

Medium Cut-Off Versus High-Flux Hemodialysis Membranes and Clinical Outcomes: A Cohort Study Using Inverse Probability Treatment Weighting

Rationale & Objective

This study investigated the effects on patients’ outcomes of using medium cutoff (MCO) versus high-flux (HF) dialysis membranes.

Study Design

A retrospective, observational, multicenter, cohort study.

Setting & Participants

Patients aged greater than 18 years receiving hemodialysis at the Baxter Renal Care Services dialysis network in Colombia. The inception of the cohort occurred from September 1, 2017, to November 30, 2017, with follow-up to November 30, 2019.

Exposure

The patients were divided into 2 cohorts according to the dialyzer used at the inception: (1) MCO membrane or (2) HF membrane.

Outcomes

Primary outcomes were the hospitalization rate from any cause and hospitalization days per patient-year. Secondary outcomes were acute cardiovascular events and mortality rates from any cause and secondary to cardiovascular causes. Laboratory parameters were assessed throughout the 2-year follow-up period.

Analytical Approach

Descriptive statistics were used to report population characteristics. Inverse probability of treatment weighting was applied to each group before analysis. All categorical variables were compared using Pearson’s χ² test, and continuous variables were analyzed with the t test. Baseline differences between groups with a value of >10% were considered clinically meaningful. Laboratory variables were measured at 5 consecutive time points. A between-patient effect was analyzed using a split-plot factorial analysis of variance.

Results

The analysis included 1,098 patients, of whom 564 (51.3%) were dialyzed with MCO membranes and 534 (48.7%) with HF membranes. Patients receiving hemodialysis with MCO membranes had a lower all-cause hospitalization incidence rate (IR) per patient-year (IR = 0.93; 95% CI, 0.82-1.03) than those receiving hemodialysis with HF membranes (IR = 1.13; 95% CI, 0.96-1.30), corresponding to a significant incident rate ratio (MCO/HF) of 0.82 (95% CI, 0.68-0.99; P = 0.04). The frequency of nonfatal cardiovascular events showed statistical significance, with a lower incidence in the MCO group (incident rate ratio = 0.66; 95% CI, 0.46-0.96; P = 0.03). No statistically significant differences in all-cause time until death were observed (P = 0.48). Albumin levels were similar between the 2 dialyzer cohorts.

Limitations

Despite the robust statistical analysis, there remains the possibility that unmeasured variables may still generate residual imbalance and, therefore, skew the results.

Conclusions

The incidences of hospitalization and cardiovascular events in patients receiving hemodialysis were lower when dialyzed with MCO membranes than HF membranes. A randomized controlled trial would be desirable to confirm these results.

Trial Registration

Clinical Trials.gov, ISRCTN12403265.

Clinical Outcomes With Medium Cut-Off Versus High-Flux Hemodialysis Membranes: A Systematic Review and Meta-Analysis

BACKGROUND

A novel medium cut-off (MCO) dialyzer (Theranova, Baxter Healthcare, Deerfield, IL, USA) enhances large middle molecule clearance while retaining selectivity for molecules >45 000 Da.

OBJECTIVE

We undertook a systematic review and meta-analysis evaluating clinical outcomes with MCO vs high-flux membranes.

METHODS

We searched MEDLINE, EMBASE, CINAHL, Cochrane Library, and Web of Science through July 2020, and gray literature sources from 2017. We included randomized (RS) and nonrandomized studies (NRS) comparing MCO and high-flux membranes in adults receiving maintenance hemodialysis. Pairs of reviewers performed study selection, data extraction, and risk of bias assessment in duplicate. We conducted random-effects pairwise meta-analyses to pool results across studies and used the Grading of Recommendations Assessment, Development and Evaluation approach to assess evidence certainty.

RESULTS

We identified 22 eligible studies (6 RS, 16 NRS; N = 1811 patients; patient-years = 1546). The MCO dialyzer improved (estimate; 95% confidence interval [CI]; certainty rating) quality of life (mean difference [MD] = 16.7/100 points; 6.9 to 26.4; moderate), Kidney Disease Quality of Life Instrument (KDQOL) subscales-burden (MD = 4.0; 1.1 to 6.9; moderate) and effects (MD = 5.4; 3.2 to 7.6; moderate), pruritus (MD = -4.4; -7.1 to -1.7; moderate), recovery time (MD = -420 minutes; -541 to -299; high), and restless legs syndrome (odds ratio = 0.39; 0.29 to 0.53; moderate). There was little to no difference in all-cause mortality (risk difference = -0.4%; -2.8 to 2.1; moderate) and serious adverse events (rate ratio = 0.63; 0.38 to 1.04; low). MCO dialysis reduced hospitalization (rate ratio = 0.48; 0.27 to 0.84; low), infection (rate ratio = 0.38; 0.17 to 0.85; moderate), hospitalization days (MD = -1.5 days; 95% CI, -2.22 to -0.78; moderate), erythropoiesis resistance index (MD = -2.92 U/kg/week/g/L; 95% CI, -4.25 to -1.6; moderate) and cumulative iron use over 12 weeks (MD = -293 mg; 95% CI, -368 to -218; moderate). We found with low certainty that MCO dialysis had little to no effect on KDQOL symptoms/problem list, pain, and physical health and moderate certainty that MCO dialysis likely has no effect on the KDQOL mental health composite.

CONCLUSIONS

We found with predominantly moderate certainty that the MCO dialyzer improves several patient-important outcomes with no apparent risks or harms. More definitive studies are needed to better quantify the effects of MCO membranes on mortality, hospitalization, and other rare events.

Effects of Medium Cut-Off Versus High-Flux Hemodialysis Membranes on Biomarkers: A Systematic Review and Meta-Analysis

BACKGROUND

Medium cut-off (MCO) membranes enhance large middle-molecule clearance while selectively retaining molecules >45 000 Da.

OBJECTIVES

We undertook a systematic review and meta-analysis comparing the effects of MCO versus high-flux membranes on biomarkers.

METHODS

We searched MEDLINE, Embase, CINAHL, Cochrane Library, and Web of Science from January 2015 to July 2020, and gray literature sources from 2017. We included randomized (RS) and nonrandomized studies (NRS) comparing MCO and high-flux membranes in adults (>18 years) receiving maintenance hemodialysis. We performed study selection, data extraction, and quality appraisals in duplicate and used the Grading of Recommendations Assessment, Development, and Evaluation framework. Outcomes included solute removal (plasma clearance or dialysate quantitation), reduction ratios, and predialysis serum concentrations for a range of prespecified large middle molecules.

RESULTS

We identified 26 eligible studies (10 RS and 16 NRS; N = 1883 patients; patient-years = 1366.3). The mean difference (MD) for albumin removal was 2.31 g per session (95% confidence interval [CI], 2.79 to 1.83; high certainty), with a reduction in predialysis albumin of -0.12 g/dl (95% CI, -0.16 to -0.07; I 2 = 0%; high certainty) in the first 24 weeks, returning to normal (MD = -0.02 g/dl, 95% CI, -0.07 to -0.03; I 2 = 56%; high certainty) after 24 weeks. We also found with high certainty that MCO dialysis resulted in a large increase (standardized mean difference [SMD]> 2.0 for all) in β2-microglobulin, κ- and λ-free light chains, and myoglobin removal, resulting in moderate (SMD > 0.5) to large (SMD > 0.8) reductions in predialysis concentrations for all of these solutes. Medium cut-off dialysis increased the reduction ratio for tumor necrosis factor-alpha (TNF-α) by 7.7% (95% CI, 4.7 to 10.6; moderate certainty), and reduced predialysis TNF-α by SMD -0.48 (95% CI, -0.91 to -0.04; moderate certainty). We found with moderate certainty that MCO dialysis had little to no effect on predialysis interleukin-6 (IL-6) plasma concentrations. Medium cut-off dialysis reduced mRNA expression of TNF-α and IL-6 in peripheral leukocytes by MD -15% (95% CI, -19.6 to -10.4; moderate certainty) and -8.8% (95% CI, -10.2 to -7.4; moderate certainty), respectively.

CONCLUSION

Medium cut-off dialysis increases the clearance of a wide range of large middle molecules and likely reduces inflammatory mediators with a concomitant transient reduction in serum albumin concentration. The net effect of MCO dialysis on large middle molecules could translate into important clinical effects.

Clinical Assessment of Dialysis Recovery Time and Symptom Burden: Impact of Switching Hemodialysis Therapy Mode

Introduction

Most people on hemodialysis (HD) report a high symptom burden. Fatigue and lack of energy are prominent, interfering with daily life and associated with poor outcome. Prolonged recovery time after each of the thrice weekly dialysis treatments is common. The impact of HD therapies, like expanded hemodialysis (HDx), on patient reported recovery time and symptom burden is unclear.

Methods

A dialysis unit decided to perform regular assessments of patient-reported symptom burden, using the POS-S Renal Symptom questionnaire and the “Recovery time from last dialysis session” question as part of routine patient focused care. At a similar time, a clinical evidence-based decision was taken to switch the in-center dialysis cohort from regular high-flux dialysis membrane to medium cut-off (MCO) membrane, introducing HDx therapy.

Results

Quarterly assessment of patient-reported symptom burden was well accepted. A sustained clinically relevant reduction in post-dialysis recovery time was observed following the therapy switch. In patients providing data up to 12 months (N = 58), median recovery time decreased from 210 min (IQR 7.5–600) to 60 min (0–210; p = 0.002) and 105 min (0–180; p = 0.001) at 6 and 12 months, respectively. Thirty-six percent of individuals reported a recovery time longer than 360 minutes at the initial assessment, which decreased to 9% at 12 months. The POS-S Renal total symptom score showed a decrease at 6 months but no difference from baseline at 12 months. The “fatigue/lack of energy” symptom showed a sustained improvement; the percentage of participants scoring its impact as “severe” or “overwhelming” decreased from 28% at baseline to 16% at 12 months. Changes in other symptoms were more variable.

Conclusion

Regular assessment of patient reported symptoms is feasible in routine dialysis practice and can help in evaluating the impact of clinical interventions. Observations suggest that HDx therapy may reduce post-dialysis recovery time and improve perceived fatigue level.

Hemodiálisis extendida frente a convencional o hemodiafiltración en línea. Estudio comparativo de necesidad de heparina y coagulación del sistema

Introducción: La reciente aparición de membranas de corte medio ofrece una alternativa para la eliminación de moléculas medianas y nueva terapia dialítica, la hemodiálisis expandida. Estas membranas se caracterizan por un mayor tamaño de poro que podría afectar a la eliminación de la heparina utilizada durante las sesiones de hemodiálisis. Objetivo: Determinar si existen diferencias en la necesidad de heparina y el estado de coagulación del sistema y dializador según técnica dialítica empleada. Material y Método: Estudio cuasiexperimental en pacientes en hemodiálisis con dos periodos de estudio, en el primero, el paciente realizó hemodiálisis convencional o hemodiafiltración y en el segundo, hemodiálisis expandida con membranas de corte medio. Resultados: El dializador quedó parcialmente coagulado en el 10,3% de las sesiones de hemodiálisis expandida frente al 19,1% de las sesiones de hemodiálisis y el 11,4% de hemodiafiltración (p=0,011). Conclusiones: La hemodiálisis expandida ofrece mejor estado de coagulación final del sistema y dializador que otras membranas.

Expanded hemodialysis as effective alternative to on-line hemodiafiltration: A randomized mid-term clinical trial

Expanded hemodialysis (HDx), using medium cut-off membrane, is a novel therapy that effectively clears middle molecules (MMs). We aimed to compare HDx to hemodiafiltration (HDF) in an open randomized clinical study. Patients currently on HDF (age 18-80 years; on HDF >3 months) were randomized to switch to HDx (N = 21) or continue HDF (N = 22) with a 24-week follow-up. Pre- to post-dialysis reduction ratios (RR) and changes in pre-dialysis levels over time were evaluated for MMs and clinical biomarkers. Use of erythropoiesis-stimulating agents (ESAs) was assessed. HDx showed greater RR for YKL-40 while RR appeared similar between groups for beta₂ -microglobulin, FGF-23, and free light chains. Intradialytic changes in inflammatory biomarkers (IL-6, CRP, PTX3) did not differ between therapies. Changes from baseline to 12 and 24 weeks did not differ between groups for MMs, inflammatory markers, albumin, fibrinogen, hemoglobin, PTH, and phosphorus. Use of ESAs tended to decrease in HDx arm while remaining stable in HDF arm. HDx appeared safe with similar clinical effectiveness as HDF. With fewer requirements and resource needs, HDx provides an attractive alternative to HDF.

Expanded Haemodialysis as a Current Strategy to Remove Uremic Toxins

Chronic kidney disease (CKD) is characterized by the retention of solutes named uremic toxins, which strongly associate with high morbidity and mortality. Mounting evidence suggests that targeting uremic toxins and/or their pathways may decrease the risk of cardiovascular disease in CKD patients. Dialysis therapies have been developed to improve removal of uremic toxins. Advances in our understanding of uremic retention solutes as well as improvements in dialysis membranes and techniques (HDx, Expanded Hemodialysis) will offer the opportunity to ameliorate clinical symptoms and outcomes, facilitate personalized and targeted dialysis treatment, and improve quality of life, morbidity and mortality.

Effect of dialyzer membranes on mortality in uremic patients undergoing long-term hemodialysis: A Nationwide population-based study using the Taiwan Dialysis Registry Data System 2005-2012

The characteristics in dialyzer are associated with mortality in patients with end-stage renal disease (ESRD) receiving hemodialysis (HD). This study is to investigate the effects of dialyzer membranes on 3-year mortality in ESRD patients. From the long-term nationwide population database. Prevalent HD patients during 2005-2012 were enrolled. Our main analysis to calculate the effect was cox regression multivariate model. Overall, the mean age of all population (N = 73 565) was 61.0 ± 13.6 years, the observation period is 2.46 years ±0.98 within 3 years and 64.6% used polysulfone (PS), polymethyl methacrylate (PMMA) (11.6%), polyethersulfone (11.4%), and cellulose triacetate (CTA) (10.7%), ethylene vinyl alcohol (EVAL) (hazard ratio [HR] 2.72, 95% confidence interval [CI] 1.71-4.33) and CTA (HR 1.35, 95% CI 1.12-1.64) were associated with higher mortality than PS, but PMMA was not. EVAL and CTA adversely affected mortality and PMMA had no protective role. Further investigations on membrane characters on HD patients are warranted. Taipei Medical University (TMU) (TMU-JIRB (No. N201804051).

An initial evaluation of expanded hemodialysis on hospitalizations, drug utilization, costs, and patient utility in Colombia

To examine new evidence linking expanded hemodialysis (HDx) using a medium cut‐off (MCO) membrane with hospitalizations, hospital days, medication use, costs, and patient utility. This retrospective study utilized data from Renal Care Services medical records database in Colombia from 2017 to 2019. Clinics included had switched all patients from high flux hemodialysis (HD HF) to HDx and had at least a year of data on HD HF and HDx. Data included demographic characteristics, comorbidities, years on dialysis, hospitalizations, medication use, and quality of life measured by the 36 item and Short Form versions of the Kidney Disease Quality of Life survey at the start of HDx, and 1 year after HDx, which were mapped to EQ‐5D utilities. Generalized linear models were run on the outcomes of interest with an indicator for being on HDx. Annual cost estimates were also constructed. The study included 81 patients. HDx was significantly associated with lower dosing of erythropoietin stimulating agents, iron, hypertension medications, and insulin. HDx was also significantly associated with lower hospital days per year (5.94 on HD vs. 4.41 on HDx) although not with the number of hospitalizations. Estimates of annual hospitalization costs were 23.9% lower using HDx and patient utilities did not appear to decline. HDx was statistically significantly associated with reduced hospitalization days and lower medication dosages. Furthermore, this preliminary analysis suggested potential for HDx being a dominant strategy in terms of costs and utility and should motivate future work with larger samples and better controls.

Slipping Through the Pores: Hypoalbuminemia and Albumin Loss During Hemodialysis

Hypoalbuminemia results when compensatory mechanisms are unable to keep pace with derangements in catabolism/loss and/or decreased synthesis of albumin. Across many disease states, including chronic kidney disease (CKD), hypoalbuminemia is a well-established, independent risk factor for adverse outcomes, including mortality. In the setting of CKD, reduced serum albumin concentrations are often a manifestation of protein-energy wasting, a state of metabolic and nutritional alterations resulting in reduced protein and energy stores. The progression of CKD to kidney failure and the initiation of maintenance hemodialysis (HD) further predisposes an already at-risk population toward hypoalbuminemia such that approximately 60% of HD patients have albumin concentrations <4.0 g/dl. Albumin loss into the dialysate through the dialyzer appears to be a potentially modifiable cause of hypoalbuminemia in some patients. A group of newer dialyzers for maintenance HD-sometimes termed protein-leaking or medium cut-off membranes-aim to improve clearance of middle molecules (vs high flux dialyzers) but are associated with increased albumin losses. In this article, we will examine the impact of dialyzer selection on albumin losses during conventional HD, including the clinical relevance of such losses on serum albumin levels. Data on the clinical relevance of albumin losses during dialysis and current gaps in the evidence base are also discussed.

Medium cut-off dialyzers in a large population of hemodialysis patients in Colombia: COREXH registry

Expanded hemodialysis (HDx) provides increased clearance of conventional and large middle molecules through innovative medium cutoff (MCO) membranes. However, there is a paucity of real-world data regarding the benefits and safety of HDx. This large observational study evaluated outcomes among patients in Colombia undergoing HDx at a extended dialysis clinical services provider. This was a prospective single cohort study of prevalent patients who were treated with HDx; baseline information was collected from the most recent data before patients were started on HDx. Patients were followed prospectively for 1 year for changes in serum albumin and other laboratory parameters compared with the baseline. Survival, hospitalization and safety were assessed from the start of HDx. A total of 1000 patients were invited to enroll; 992 patients met the inclusion criteria for data analysis and 638 patients completed the year of follow-up. Seventy-four (8%) patients died during 866 patient-years (PY) of follow-up; the mortality rate was 8.54 deaths/100 PY (95% confidence interval [CI], 6.8-10.7). There were 673 hospitalization events with a rate of 0.79 events/PY (95% CI, 0.73-0.85) with 6.91 hospital days/PY (95% CI, 6.74-7.09). The observed variability from baseline and maximum average change in mean serum albumin levels were -1.8% and -3.5%, respectively. No adverse events were related to the MCO membrane. HDx using an MCO membrane maintains stable serum albumin levels and is safe in terms of nonoccurrence of dialyzer related adverse events.