Haemodialysis removes excess fluid and metabolic products from the blood in people who have limited kidney function. Haemodialysis membranes are classified as high-flux or low-flux based on their ability to remove fluid and molecules. It has been suggested that removal of larger solutes across high-flux haemodialysis membranes may better reflect normal kidney function and improve clinical outcomes. To investigate this issue, we analysed 33 studies that involved 3820 people which directly compared haemodialysis using high-flux or low-flux membranes.
We found that high-flux dialysis membranes reduced deaths from heart and circulatory (cardiovascular) causes by 17%, but did not reduce overall risk of death. This means that if 100 people were treated with high-flux dialysis for approximately two years, three deaths from cardiovascular causes may be prevented in people who need long-term haemodialysis.
Based on the available evidence, we could not be certain that the type of membrane flux involved had any effect on deaths from infection, hospital admissions, joint problems due to long term dialysis, quality of life, or kidney function in people on long-term haemodialysis.
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.
Clinical practice guidelines regarding the use of high-flux haemodialysis membranes vary widely.
We aimed to analyse the current evidence reported for the benefits and harms of high-flux and low-flux haemodialysis.
We searched the Cochrane Renal Group's Specialised Register (July 2012) through contact with the Trials Search Co-ordinator using search terms relevant to this review. The Cochrane Renal Group’s Specialised Register contains studies identified from the following sources:Quarterly searches of the Cochrane Central Register of Controlled Trials CENTRAL, weekly searches of MEDLINE OVID SP, handsearching of renal-related journals and the proceedings of major renal conferences, searching of the current year of EMBASE OVID SP, weekly current awareness alerts for selected renal journals and searches of the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.
We included randomised controlled trials (RCTs) that compared high-flux haemodialysis with low-flux haemodialysis in people with end-stage kidney disease (ESKD) who required long-term haemodialysis.
Data were extracted independently by two authors for study characteristics (participants and interventions), risks of bias, and outcomes (all-cause mortality and cause-specific mortality, hospitalisation, health-related quality of life, carpal tunnel syndrome, dialysis-related arthropathy, kidney function, and symptoms) among people on haemodialysis. Treatment effects were expressed as a risk ratio (RR) or mean difference (MD), with 95% confidence intervals (CI) using the random-effects model.
We included 33 studies that involved 3820 participants with ESKD. High-flux membranes reduced cardiovascular mortality (5 studies, 2612 participants: RR 0.83, 95% CI 0.70 to 0.99) but not all-cause mortality (10 studies, 2915 participants: RR 0.95, 95% CI 0.87 to 1.04) or infection-related mortality (3 studies, 2547 participants: RR 0.91, 95% CI 0.71 to 1.14). In absolute terms, high-flux membranes may prevent three cardiovascular deaths in 100 people treated with haemodialysis for two years. While high-flux membranes reduced predialysis beta-2 microglobulin levels (MD -12.17 mg/L, 95% CI -15.83 to -8.51 mg/L), insufficient data were available to reliably estimate the effects of membrane flux on hospitalisation, carpal tunnel syndrome, or amyloid-related arthropathy. Evidence for effects of high-flux membranes was limited by selective reporting in a few studies. Insufficient numbers of studies limited our ability to conduct subgroup analyses for membrane type, biocompatibility, or reuse. In general, the risk of bias was either high or unclear in the majority of studies.