Randomized trial of high-flux vs low-flux haemodialysis: effects on homocysteine and lipids. Secondary prevention with antioxidants of cardiovascular disease in endstage renal disease (SPACE): randomised placebo-controlled trial. On-line haemodiafiltration versus low-flux haemodialysis. A prospective randomized study. Effect of dialysis dose and membrane flux in maintenance hemodialysis. Low-flux versus high-flux synthetic dialysis membrane in acute renal failure: prospective randomized study. Continuous venovenous haemodiafiltration versus intermittent haemodialysis for acute renal failure in patients with multiple-organ dysfunction syndrome: a multicentre randomised trial. Five-year findings of the hypertension detection and follow-up program. I. Reduction in mortality of persons with high blood pressure, including mild hypertension. Hypertension Detection and Follow-up Program Cooperative Group. Do high-flux dialysis membranes affect renal dyslipidemia? Effect of high-flux dialysis on the anaemia of haemodialysis patients.
Uncontrolled studies have found that high-flux haemodialysis favourably modifies homocysteine and lipid profiles. We sought to confirm these findings by carrying out a randomized prospective comparison of high-flux and low-flux polysulphone in chronic, stable dialysis patients.
                Forty-eight patients were randomly assigned to either high or low-flux dialysis for 3 months. Serum levels of homocysteine, lipoprotein (a), and lipids were compared between the treatment groups at monthly intervals.
                All patient characteristics and laboratory variables were equally distributed between the groups at baseline. Over the study duration, we observed no differences between high- and low-flux treatment groups for the following outcomes: pre-dialysis homocysteine, lipoprotein (a), total cholesterol, HDL cholesterol, LDL cholesterol, triglycerides (all P>0.05). Geometric mean (interquartile range) homocysteine at baseline was 20.0 (16.8-24.5) and 19.5 (15.3-22.0) micromol/l for the high-and low-flux groups respectively (P=0.80), and levels did not change significantly during the study. We did demonstrate a more pronounced intradialytic effect of high-flux dialysis on homocysteine levels, which fell during dialysis by 42%, compared to 32% with low-flux dialysis (P<0. 001).
                In this randomized controlled trial, the effects of high-flux and low-flux haemodialysis on homocysteine and lipid profiles were comparable. The greater intradialytic effect of high-flux dialysis on homocysteine did not translate into a significant difference in pre-dialysis levels after 3 months of study. Excess cardiovascular mortality has been documented in chronic haemodialysis patients. Oxidative stress is greater in haemodialysis patients with prevalent cardiovascular disease than in those without, suggesting a role for oxidative stress in excess cardiovascular disease in haemodialysis. We investigated the effect of high-dose vitamin E supplementation on cardiovascular disease outcomes in haemodialysis patients with pre-existing cardiovascular disease.
                Haemodialysis patients with pre-existing cardiovascular disease (n=196) aged 40-75 years at baseline from six dialysis centres were enrolled and randomised to receive 800 IU/day vitamin E or matching placebo. Patients were followed for a median 519 days. The primary endpoint was a composite variable consisting of: myocardial infarction (fatal and non-fatal), ischaemic stroke, peripheral vascular disease (excluding the arteriovenous fistula), and unstable angina. Secondary outcomes included each of the component outcomes, total mortality, and cardiovascular-disease mortality.
                A total of 15 (16%) of the 97 patients assigned to vitamin E and 33 (33%) of the 99 patients assigned to placebo had a primary endpoint (relative risk 0.46 [95% CI 0.27-0.78], p=0.014). Five (5.1%) patients assigned to vitamin E and 17 (17.2%) patients assigned to placebo had myocardial infarction (0.3 [0.11-0.78], p=0.016). No significant differences in other secondary endpoints, cardiovascular disease, or total mortality were detected.
                In haemodialysis patients with prevalent cardiovascular disease, supplementation with 800 IU/day vitamin E reduces composite cardiovascular disease endpoints and myocardial infarction. Current methods of renal replacement therapy lead only to an insignificant removal of larger, potentially toxic, substances, which are excreted by healthy kidneys. On-line preparation of substituate from dialysate and the use of high-flux membranes allow substantial convective removal of such substances. A modified on-line haemodiafiltration method with the use of a large membrane surface and a high convective part was chosen to test whether the elimination of larger substances, such as low-molecular-mass proteins, has a clinical impact.
                In a prospective, controlled study over 24 months, 44 unselected chronic dialysis patients were randomized to undergo either low-flux haemodialysis (HD; n = 21) or haemodiafiltration (HDF; n = 23). To eliminate confounding factors, low-molecular efficacy was matched (Kt/V 1.8), and the same membrane material (polysulfone), ultrapure dialysate and the same treatment duration (4.5 h) were applied to each group.
                Morbidity, mortality, blood pressure, dialysis-associated hypotensive episodes, haematocrit and erythropoietin dose did not differ between the groups. The same was true for body weight and, accordingly, bioimpedance values, clinical hydration score, skinfold thickness, plasma albumin, prealbumin and transferrin. beta2-Microglobulin in the plasma did not change in the HD group and varied between 32 and 43 mg/l throughout the 2 years. In HDF, beta2 microglobulin decreased from similar values to 18 mg/l predialysis (P<0.01) in the first 6 months of HDF treatment and then remained constant during the remaining 18 months.
                In the absence of any clinical marker of uraemic toxicity the removal of larger molecules over the time-span of 2 years during HDF had no clinical implication compared with extremely (and for routine practice unrealistically) well-dialysed patients with low-flux HD. In the absence of any side-effects of on-line HDF and supposing that plasma beta2-microglobulin is a marker of morbidity, on-line HDF ensures an excellent dialysis quality which apparently takes time to translate into measurable clinical sequelae. The effects of the dose of dialysis and the level of flux of the dialyzer membrane on mortality and morbidity among patients undergoing maintenance hemodialysis are uncertain.
                We undertook a randomized clinical trial in 1846 patients undergoing thrice-weekly dialysis, using a two-by-two factorial design to assign patients randomly to a standard or high dose of dialysis and to a low-flux or high-flux dialyzer.
                In the standard-dose group, the mean (+/-SD) urea-reduction ratio was 66.3+/-2.5 percent, the single-pool Kt/V was 1.32+/-0.09, and the equilibrated Kt/V was 1.16+/-0.08; in the high-dose group, the values were 75.2+/-2.5 percent, 1.71+/-0.11, and 1.53+/-0.09, respectively. Flux, estimated on the basis of beta2-microglobulin clearance, was 3+/-7 ml per minute in the low-flux group and 34+/-11 ml per minute in the high-flux group. The primary outcome, death from any cause, was not significantly influenced by the dose or flux assignment: the relative risk of death in the high-dose group as compared with the standard-dose group was 0.96 (95 percent confidence interval, 0.84 to 1.10; P=0.53), and the relative risk of death in the high-flux group as compared with the low-flux group was 0.92 (95 percent confidence interval, 0.81 to 1.05; P=0.23). The main secondary outcomes (first hospitalization for cardiac causes or death from any cause, first hospitalization for infection or death from any cause, first 15 percent decrease in the serum albumin level or death from any cause, and all hospitalizations not related to vascular access) also did not differ significantly between either the dose groups or the flux groups. Possible benefits of the dose or flux interventions were suggested in two of seven prespecified subgroups of patients.
                Patients undergoing hemodialysis thrice weekly appear to have no major benefit from a higher dialysis dose than that recommended by current U.S. guidelines or from the use of a high-flux membrane.
                Copyright 2002 Massachusetts Medical Society The influence of dialyzer membrane on the morbidity and mortality of patients with acute renal failure remains a matter of debate. The aim of the prospective randomized clinical study was to assess the influence of the flux of a synthetic dialyzer membrane on patients' survival rate, restitution of renal function, and duration of hemodialysis treatment of patients with acute renal failure as a part of multiorgan failure. Seventy-two patients treated in intensive care units of the University Medical Center Ljubljana were randomized according to the dialyzer used throughout the duration of hemodialysis treatment. There were 38 patients in the low-flux group (dialyzer F6, low-flux polysuphone, Fresenius, Bad Homburg, Germany) and 34 patients in the high-flux group (dialyzer Filtral 12, sulphonated high-flux polyacrylonitrile, Hospal, Industrie Meyzieu, France). Both groups were balanced in terms of sex, age, APACHE II score, oliguria before dialysis, cause of acute renal failure, inotropic support, mechanical ventilation, and the number of failing organs. The patients' survival rate was 18.7% in the low-flux group and 20.6% in the high-flux group. Ten patients (26.3%) recovered their renal function in the low-flux group and 8 (23.5%) in the high-flux group. Hemodialysis treatment lasted 11.2 days in the low-flux and 10.7 days in the high-flux group. An analysis of subgroups with a lower mortality rate (subgroup of patients without oliguria and subgroup of patients with less than 4 failed organ systems) did not show significant differences between the low-flux and high-flux groups in terms of survival rate, recovery of renal function, and duration of hemodialysis treatment. In conclusion, no significant differences were found in the results of low-flux versus high-flux synthetic membrane dialyzer treatment in patients with acute renal failure as a part of multiorgan failure in terms of survival rate, recovery of renal function, incidence of oliguria during hemodialysis, and duration of hemodialysis treatment. The number of failing organs seems to be the most important single factor determining the survival of patients with acute renal failure as a part of multiorgan failure. Whether continuous renal replacement therapy is better than intermittent haemodialysis for the treatment of acute renal failure in critically ill patients is controversial. In this study, we compare the effect of intermittent haemodialysis and continuous venovenous haemodiafiltration on survival rates in critically ill patients with acute renal failure as part of multiple-organ dysfunction syndrome.
                Our prospective, randomised, multicentre study took place between Oct 1, 1999, and March 3, 2003, in 21 medical or multidisciplinary intensive-care units from university or community hospitals in France. Guidelines were provided to achieve optimum haemodynamic tolerance and effectiveness of solute removal in both groups. The two groups were treated with the same polymer membrane and bicarbonate-based buffer. 360 patients were randomised, and the primary endpoint was 60-day survival based on an intention-to-treat analysis.
                Rate of survival at 60-days did not differ between the groups (32% in the intermittent haemodialysis group versus 33% in the continuous renal replacement therapy group [95 % CI -8.8 to 11.1,]), or at any other time.
                These data suggest that, provided strict guidelines to improve tolerance and metabolic control are used, almost all patients with acute renal failure as part of multiple-organ dysfunction syndrome can be treated with intermittent haemodialysis. The Hypertension Detection and Follow-up Program (HDFP), in a community-based, randomized controlled trial involving 10,940 persons with high blood pressure (BP), compared the effects on five-year mortality of a systematic antihypertensive treatment program (Stepped Care [SC]) and referral to community medical therapy (Referred Care [RC]). Participants, recruited by population-based screening of 158,906 people aged 30 to 69 years in 14 communities througout the United States, were randomly assigned to SC or RC groups within each center and by entry diastolic blood pressure (DBP) (90 to 104, 105 to 114, and 115 + mm Hg). Over the five years of the study, more than two thirds of the SC participants continued to receive medication, and more than 50% achieved BP levels within the normotensive range, at or below the HDFP goal for DBP. Controls of BP was consistently better for the SC than for the RC group. Five-year mortality from all causes was 17% lower for the SC group compared to the RC group (6.4 vs 7.7 per 100, P less than .01) and 20% lower for the SC subgroup with entry DBP of 90 to 104 mm Hg compared to the corresponding RC subgroup (5.9 vs 7.4 per 100, P less than .01). These findings of the HDFP indicate that the systematic effective management of hypertension has a great potential for reducing mortality for the large numbers of people with high BP in the population, including those with "mild" hypertension. High-flux hemodialysis has been reported to attenuate renal dyslipidemia. To evaluate the contribution of dialysis membrane composition per se, we compared the impact on the lipoprotein profile of hemodialysis (HD) with a conventional cellulose dialysis membrane with that of a synthetic high-flux dialysis membrane in standard hemodialysis mode. Forty-two patients (24 men, 18 women; mean age, 69 years; range, 39-85 years) on maintenance HD with cellulosic dialysis membranes were randomized and stratified for diabetes mellitus to 12 weeks of HD treatment with either a cellulose acetate (CA; n = 23) or polyacrylonitrile (AN69; n = 19) membrane. HD was performed in a conventional low-flux standard HD mode 4-6 hours/session. Plasma levels of lipids (TC, TG), apolipoproteins (A-I, B, C-III, E), lipoprotein (a) (Ip(a)), and individual apoA and apoB containing lipoproteins (LP-A-I, LP-A-I:A-II, LP-B, LP-Bc) were determined. At baseline, the AN69 group had slightly higher plasma concentrations of apoC-III and C-III/HS, but there were no other differences at entry in study variables between the treatment groups. Twelve week treatment with an AN69 membrane did not result in any significant changes in lipoprotein profile compared with treatment with a cellulose acetate membrane. HD with AN69 dialysis membranes in the conventional low-flux standard hemodialysis mode does not affect the lipoprotein profile. Anaemia is one of the major clinical characteristics of patients with chronic renal failure, and has a considerable effect on morbidity and mortality. Adequate dialysis is of paramount importance in correcting anaemia by removing small and medium-sized molecules, which may inhibit erythropoiesis. However, high-molecular-weight inhibitors cleared only by means of highly porous membranes have also been found in uraemic serum and it has been claimed from uncontrolled studies that high-flux dialysis could improve anaemia in haemodialysis patients.
                We therefore planned this multicentre randomized controlled trial with the aim of testing whether the use of a large-pore biocompatible membrane for a fixed 12-week follow-up improves anaemia in haemodialysis patients in comparison with the use of a conventional cellulose membrane. Eighty-four (5.3%) of a total of 1576 adult haemodialysed patients attending 13 Dialysis Units fulfilled the entry criteria and were randomly assigned to the experimental treatment (42 patients) or conventional treatment (42 patients).
                Haemoglobin levels increased non-significantly from 9.5+/-0.8 to 9.8+/-1.3 g/dl (dP=0. 069) in the population as a whole, with no significant difference between the two groups (P:=0.485). Erythropoietin therapy was given to 32/39 patients (82%) in the conventional group, and 26/35 (74%) in the experimental group (P:=0.783) with subcutaneous administration to 26/32 patients in conventional and to 23/26 patients in experimental group, P:=0.495. Dialysis dose (Kt/V) remained constant in both groups (from 1.30+/-0.17 to 1.33+/-0.20 in the conventional group and from 1.28+/-0.26 to 1.26+/-0.21 in the experimental group, P:=0.242). Median pre- and post-dialysis beta(2)-microglobulin levels remained constant in the conventional group (31.9 and 34.1 mg/dl at baseline) and decreased in the experimental group (pre-dialysis values from 31.1 to 24.7 mg/dl, P:=0.004 and post-dialysis values from 24.8 to 20.8 mg/dl, P:=0.002). Median erythropoietin doses were not different at baseline (70 IU/kg/week in conventional treatment and 90 IU/kg/week in experimental treatment, P:=0.628) and remained constant during follow-up (from 70 to 69 IU/kg/week in the conventional group and from 90 to 91 IU/kg/week in the experimental group, P:=0.410). Median erythropoietin plasma levels were in the normal range and remained constant (from 12.1 to 12.9 mU/ml in the conventional group and from 13.2 to 14.0 mU/ml in the experimental group, P:=0.550).
                This study showed no difference in haemoglobin level increase between patients treated for 3 months with a high-flux biocompatible membrane in comparison with those treated with a standard membrane. When patients are highly selected, adequately dialysed, and have no iron or vitamin depletion, the effect of a high-flux membrane is much less than might be expected from the results of uncontrolled studies.
High-flux haemodialysis may reduce cardiovascular mortality in people requiring haemodialysis by about 15%. A large well-designed RCT is now required to confirm this finding.