A randomized, controlled study of the consequences of hemodialysis membrane composition on erythropoietic response

Reporting of "dialysis adequacy" as an outcome in randomised trials conducted in adults on haemodialysis

Background

Clinical trials are most informative for evidence-based decision-making when they consistently measure and report outcomes of relevance to stakeholders, especially patients, clinicians, and policy makers. However, sometimes terminology used is interpreted differently by different stakeholders, which might lead to confusion during shared decision making. The construct dialysis adequacy is frequently used, suggesting it is an important outcome both for health care professionals as for patients.

Objective

To assess the scope and consistency of the construct dialysis adequacy as reported in randomised controlled trials in hemodialysis, and evaluate whether these align to the insights and understanding of this construct by patients.

Methods

To assess scope and consistency of dialysis adequacy by professionals, we performed a systematic review searching the Cochrane Central Register of Controlled Trials (CENTRAL) up to July 2017. We identified all randomised controlled trails (RCT) including patients on hemodialysis and reporting dialysis adequacy, adequacy or adequacy of dialysis and extracted and classified all reported outcomes. To explore interpretation and meaning of the construct of adequacy by patients, we conducted 11 semi-structured interviews with HD patients using thematic analysis. Belgian registration number B670201731001.

Findings

From the 31 included trials, we extracted and classified 98 outcome measures defined by the authors as adequacy of dialysis, of which 94 (95%) were biochemical, 3 (3%) non-biochemical surrogate and 2 (2%) patient-relevant. The three most commonly reported measures were all biochemical. None of the studies defined adequacy of dialysis as a patient relevant outcome such as survival or quality of life. Patients had a substantially different understanding of the construct dialysis adequacy than the biochemical interpretation reported in the literature. Being alive, time spent while being on dialysis, fatigue and friendliness of staff were the most prominent themes that patients linked to the construct of dialysis adequacy.

Conclusion

Adequacy of dialysis as reported in the literature refers to biochemical outcome measures, most of which are not related with patient relevant outcomes. For patients, adequate dialysis is a dialysis that enables them to spend as much quality time in their life as possible.

Tungsten doped VO2/microgels hybrid thermochromic material and its smart window application

A new thermochromic composite was successfully synthesized by a combination of HPCA microgel and W doped VO₂ nanoparticles. Within a suitable working temperature, this composite can provide excellent modulation in both the visible and IR ranges.

Temperature-responsive hydroxypropylcellulose based thermochromic material and its smart window application

Thermochromic materials are the most cost effective smart window materials and the organic hydrogel material has large solar modulating ability (ΔT_sol) and the luminous transmittance (T_lum) compared with inorganic VO₂based materials.

Sonographic measurement of renal size in patients undergoing chronic hemodialysis: Correlation with residual renal function

Previous studies have reported that renal size may change when the function is compromised. However, it is not known whether sonographically measured renal size reflects the residual renal function (RRF) in patients undergoing chronic hemodialysis. A total of 140 patients undergoing chronic hemodialysis (≥3 months) were investigated in the present study. The patients were divided into two groups according to the daily urine volume: Individuals with RRF (RRF+ group; ≥200 ml; n=65) and without RRF (RRF− group; <200 ml; n=75). Renal sizes were measured using sonography and renal volumes were calculated with the ellipsoid formula. Univariable and multivariable stepwise forward logistic regression analyses were performed to examine the correlation between the presence of RRF and various variables. The results indicated that there were statistically significant differences (P<0.001) between the RRF+ and RRF− groups with regard to renal length, width, thickness and volume of the left (length, 7.9±1.2 vs. 6.8±1.2 cm; volume, 60.0±26.7 vs. 40.2±18.1 ml, respectively) and right (length, 7.6±1.2 vs. 6.7±1.2 cm; volume, 50.2±26.5 vs. 33.9±15.3 ml, respectively) sides of the kidney. Multivariable stepwise forward logistic regression analyses showed that the mean renal length or volume and hemodialysis duration were independent predictors of the presence of RRF. Therefore, renal size assessment by ultrasonography may be useful for RRF evaluation in patients undergoing chronic hemodialysis.

A randomized controlled trial evaluating the erythropoiesis stimulating agent sparing potential of a vitamin E-bonded polysulfone dialysis membrane

Background

Vitamin E (VE) bonded polysulfone dialysis membranes have putative erythropoiesis stimulating agent (ESA)-sparing and anti-inflammatory properties based on data from a small number of studies. We sought to investigate this in a large, prospective 12-month randomized controlled trial.

Methods

Two-hundred and sixty prevalent haemodialysis (HD) patients were randomized to dialysis with VE-bonded polysulfone membranes or non-VE-bonded equivalents. All ESA-dosing was performed by means of a computer-based anaemia management decision support system. Monthly data were used to calculate the ESA resistance index (ERI) and blood tests were performed at baseline, 6 and 12 months for measurement of C-reactive protein (CRP) levels.

Results

Of the 260 patients, 123 were randomized to dialysis with the VE-membrane and 12-month data was available for 220 patients. At the study population level, no beneficial effect of the VE membranes on the ERI or CRP levels was observed. Post hoc analyses indicated that there was a significant fall in ERI for patients with the highest baseline ESA resistance dialysed with the VE (9.28 [7.70–12.5] versus 7.70 [5.34–12.7] IU/week/kg/g/dL Hb, P = 0.01) but not the control membranes (9.45 [7.62–12.3] versus 8.14 [4.44–15.6] IU/week/kg/g/dL Hb, P = 0.41); this was not attributable to changes in CRP levels.

Conclusions

Wholesale switching of all chronic HD patients to dialysis with VE-bonded polysulfone membranes appears not to be associated with improvements in ESA-responsiveness or CRP. These membranes may have utility in patients with heightened ESA resistance.

Convective therapies versus low-flux hemodialysis for chronic kidney failure: a meta-analysis of randomized controlled trials

BACKGROUND

Although convective therapies have gained popularity for the optimal removal of uremic solutes, their benefits and potential risks have not been fully elucidated. We conducted a meta-analysis of all randomized controlled trials comparing convective therapies with low-flux hemodialysis in patients with chronic kidney failure.

METHODS

We performed a literature search using MEDLINE (inception-December 2012), Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, scientific abstracts from meetings and bibliographies of retrieved articles. Randomized controlled trials comparing the effect of convective therapies including high-flux hemodialysis, hemofiltration or hemodiafiltration versus low-flux hemodialysis were included. Random-effects model meta-analyses were used to examine continuous and binary outcomes.

RESULTS

Sixty-five (29 crossover and 36 parallel-arm) trials were identified (n = 12 182). Convective therapies resulted in a decrease in all-cause mortality [relative risk (RR) 0.88; 95% confidence interval (CI) 0.76, 1.02, P = 0.09], cardiovascular mortality (RR 0.84; 95% CI 0.71, 0.98, P = 0.03), all-cause hospitalization (RR 0.91; 95% CI 0.82, 1.01; P = 0.08) and therapy-related hypotension (RR 0.55, 95% CI 0.35, 0.87, P = 0.01). Convective therapies also resulted in an increase in the clearance of several low-molecular-weight (urea, creatinine and phosphate), middle-sized (β-2 microglobulin and leptin) and protein-bound (homocysteine, advanced glycation end-products and pentosidine) solutes and a decrease in inflammatory markers (interleukin-6). There was no impact of convective therapies on cardiac morphological and functional parameters, and blood pressure and anemia parameters.

CONCLUSIONS

Although convective therapies are associated with improved clearance of uremic solutes, the potential long-term benefits of specific convective modalities require further study.

Interventions for erythropoietin-resistant anaemia in dialysis patients

BACKGROUND

People living with end-stage kidney disease (ESKD) often develop anaemia. Erythropoiesis-simulating agents (ESAs) are often given to people living with ESKD to maintain haemoglobin at a level to minimise need for transfusion. However, about 5% to 10% of patients with ESKD exhibit resistance to ESAs, and observational studies have shown that patients requiring high doses of ESA are at increased risk of mortality.

OBJECTIVES

This review aimed to study the effects of interventions for the treatment of ESA-resistant anaemia in people with ESKD.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE for randomised controlled trials (RCT) that involved participants with ESKD on dialysis or who were pre-dialysis patients with chronic kidney disease (stage 5). Date of last search: April 2013.

SELECTION CRITERIA

ESA resistance was defined as failure to achieve or maintain haemoglobin/haematocrit levels within the desired target range despite appropriate ESA doses (erythropoietin ≥ 450 U/kg/wk intravenously or ≥ 300 U/kg/wk subcutaneously; darbepoetin ≥ 1.5 µg/kg/wk) in people who were not nutritionally deficient, or who had haematological or bleeding disorders. Extended inclusion criteria for ESA hyporesponsive state were: erythropoietin dose ≥ 300 U/kg/wk and ≥ 150 U/kg/wk for intravenous administration; or ≥ 200 U/kg/wk and ≥ 100 U/kg/wk for subcutaneous administration; or darbepoetin dose ≥ 1.0 µg/kg/wk).

DATA COLLECTION AND ANALYSIS

Two authors independently assessed study quality and extracted data. Statistical analyses were performed using a random effects model and results expressed as risk ratio (RR) or mean difference (MD) with 95% confidence intervals (CI).

MAIN RESULTS

Titles and abstracts of 521 records were screened, of which we reviewed 99 from the full text. Only two studies matched our inclusion criteria. One study compared intravenous vitamin C versus no study medication for six months in 42 ESKD patients on haemodialysis who required intravenous erythropoietin (dose ≥ 450 U/kg/wk). The other included study compared high-flux dialyser versus low-flux dialyser for six months in 48 haemodialysis patients who required subcutaneous erythropoietin (dose ≥ 200 U/kg/wk). Because interventions differed, data could not be combined for quantitative meta-analysis.

AUTHORS' CONCLUSIONS

There was inadequate evidence identified to inform recommendation of any intervention to ameliorate ESA hyporesponsiveness. Adequately powered RCTs are required to establish the safety and efficacy of interventions to improve responsiveness to ESA therapy.

Dialysis adequacy and response to erythropoiesis-stimulating agents: what is the evidence base?

Despite an increase in the use and average dose of erythropoiesis-stimulating agents (ESA) over the past 15 years, a substantial percentage of patients still do not achieve hemoglobin targets recommended by international guidelines. A clear relationship among hemoglobin or hematocrit levels, ESA dose, and increase in dialysis dose has been pointed out by a number of prospective or retrospective studies. This is particularly true in patients receiving inadequate dialysis. Increasing attention also has been paid to the relationship between dialysis, increased inflammatory stimulus, and ESA response because dialysate contamination and low-compatible treatments may increase cytokine production and consequently inhibit erythropoiesis. The biocompatibility of dialysis membranes and flux are other important factors. However, in highly selected, adequately dialyzed patients without iron or vitamin depletion, the effect of these treatment modalities on anemia seems to be smaller than expected. The role of on-line treatments still is controversial given that it is still difficult to discriminate between the effect of on-line hemodiafiltration per se from that of an increased dialysis dose. Very preliminary results obtained with short or long nocturnal daily hemodialysis on anemia correction are encouraging.

Managing erythropoietin hyporesponsiveness

The anemia of chronic kidney disease is associated with cardiovascular disease, decreased quality of life, and mortality. The introduction of recombinant human erythropoietin (rHuEPO) has transformed the management of this condition. However, a significant proportion of patients fail to respond to even high doses of rHuEPO. Several factors have been implicated in the hyporesponsiveness to rHuEPO. Iron deficiency, whether absolute or functional, is considered the most important, and maintenance of adequate iron stores reduces rHuEPO requirements among patients on hemodialysis. However, traditional indices of iron that are currently utilized may not reflect iron stores accurately, and there is also increasing concern regarding the potential long-term toxicity of parenteral iron therapy. Infection and inflammation also influence the response to rHuEPO, both by disruption of iron metabolism and by eliciting the release of cytokines that inhibit erythropoiesis. Oxidative stress may contribute to rHuEPO hyporesponsiveness directly by promoting lipid peroxidation in cell membranes, leading to increased erythrocyte fragility and reduced life span and also through its strong association with inflammation. Severe hyperparathyroidism can lead to a reduced number of erythroid progenitor cells. Inadequate dialysis dose, aluminum overload, nutritional factors such as deficiencies of carnitine, vitamin B12, folic acid, and vitamin C can also reduce the efficacy of rHuEPO therapy. Hyporesponsiveness to rHuEPO presents a challenge to both diagnosis and management in an era where optimizing response to rHuEPO is critical both in limiting the burgeoning costs of anemia management and improving clinical outcomes in the dialysis population.

Anemia in children with chronic kidney disease

Anemia in children with chronic kidney disease (CKD) is common secondary to inadequate erythropoietin production, iron deficiency, blood loss, inflammation, secondary hyperparathyroidism, uremic toxins, and nutritional deficiencies. Anemia has a variety of deleterious consequences, including associations with increased mortality and left ventricular hypertrophy. Recombinant human erythropoietin is effective in treating anemia in children with CKD, and recent studies show that darbepoetin alpha is an attractive alternative because it requires less frequent injections. Iron deficiency is a major cause of anemia that is resistant to erythropoietin or darbepoetin alpha. Although oral iron is effective in some patients, many children, especially those receiving hemodialysis, require intravenous iron to replenish their iron stores. Both acute dosing and chronic dosing of intravenous iron are effective in pediatric patients.

Cellulose, modified cellulose and synthetic membranes in the haemodialysis of patients with end-stage renal disease

BACKGROUND

When the kidney fails the blood-borne metabolites of protein breakdown and water cannot be excreted. The principle of haemodialysis is that such substances can be removed when blood is passed over a semipermeable membrane. Natural membrane materials include cellulose or modified cellulose, more recently various synthetic membranes have been developed. Synthetic membranes are regarded as being more "biocompatible" in that they incite less of an immune response than cellulose-based membranes.

OBJECTIVES

To assess the effects of different haemodialysis membrane material in patients with end-stage renal disease (ESRD).

SEARCH STRATEGY

We searched MEDLINE, EMBASE, PreMEDLINE, HealthStar CINAHL, the Cochrane Central Register of Controlled Trials (CENTRAL), Biosis, SIGLE, CRIB, UK National Research Register and reference lists of relevant articles. We contacted biomedical companies, known investigators and handsearched selected journals and conference proceedings. Date of most recent search: June 2004.

SELECTION CRITERIA

All randomised controlled trials (RCTs) or quasi-RCTs comparing different haemodialysis membrane material in patients with ESRD.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed the methodological quality of studies. Data was abstracted onto a standard form by one reviewer and checked by another. Relative Risk (RR) and weighted mean difference (WMD) with 95% confidence intervals (CI)) MAIN RESULTS: Thirty two studies were identified. Pre-dialysis ss(2) microglobulin concentrations were not significantly lower in patients treated with synthetic membranes (WMD -14.67, 95% CI -33.10 to 4.05). When analysed for change in ss(2) microglobulin, a fall was only noted with high-flux membranes. The incidence of amyloid was less in patients who were dialysed for six years with high-flux synthetic membranes (one study, RR 0.03, 95% CI 0.00 to 0.54). There was a significant difference in favour of the synthetic (high-flux) membrane in comparison to cellulose membranes for triglycerides (WMD -0.66; 95% CI -1.18 to -0.14) but not for modified cellulose membranes. Dialysis adequacy measured by Kt/V was marginally higher when cellulose membranes were used (WMD -0.10; 95% CI -0.16 to 0.04), whereas synthetic membranes achieved significantly higher Kt/V values when compared with modified cellulose membranes (WMD 0.20, 95% 0.11 to 0.29) . There were no data on quality of life measures.

AUTHORS' CONCLUSIONS

We found no evidence of benefit when synthetic membranes were compared with cellulose/modified cellulose membranes in terms of reduced mortality no reduction in dialysis-related adverse symptoms. Despite the relatively large number of RCTs undertaken in this area none of the included studies reported any measures of quality of life.

Structured Conversion from Thrice Weekly to Weekly Erythropoietic Regimens Using a Computerized Decision-Support System: A Randomized Clinical Study

In view of the recent interest in weekly erythropoietic regimens and the lack of studies directly comparing the available agents, the clinical effectiveness of darbepoetin-alpha (DA) and epoetin-beta (EB), when administered via the subcutaneous route on a weekly basis, after conversion from thrice-weekly subcutaneous EB, was studied. In this 9-mo, single-center, randomized study of an unselected hemodialysis population, anemia was managed with a computerized decision-support system. Per-protocol analysis of the 81 patients in each arm who completed the study showed similar hemoglobin outcomes between treatment arms, both at randomization and at the end of the study. After conversion from thrice-weekly EB to DA (at a ratio of 200 IU:1 microg, at which products are cost-neutral in the European Union), a significant fall in dose from a mean of 0.59 microg/kg per wk after randomization to 0.46 microg/kg per wk in the last month (P = 0.002) was observed; in the comparator arm, the reduction in frequency of administration of EB was associated with a significant dose increase from a mean of 107.5 to 133.2 IU/kg per wk (P = 0.002) during the same period. At hemoglobin stability, mean EB dose was found to be 44% higher than DA dose (when multiplied by 200). Similar significant dose differences were apparent in a modified intention-to-treat analysis. The study demonstrated that, under a decision-support system, both products were capable of adequately maintaining hemoglobin outcome when administered on a weekly basis but with significant dose differences at 9 mo.