Key messages
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For adults with kidney failure (a condition where the kidneys no longer function well enough to keep a person alive), convective dialysis (a treatment that uses a strong flow of water to wash larger waste products out of the blood) probably reduces the risk of death from any cause and the risk of death from cardiovascular disease compared to standard haemodialysis.
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Convective dialysis likely results in little to no difference in nonfatal heart problems. It may make little or no difference to severe tiredness, problems with the dialysis access point, hospital stays, or the overall quality of life.
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Direct comparisons between different convective modalities were limited, and we did not detect meaningful differences.
What is kidney failure, and how is it treated?
People with kidney failure (a condition where the kidneys no longer function well enough to keep a person alive) can be treated with dialysis to remove toxins and fluid. Standard haemodialysis uses a machine to filter waste and extra water from the blood. Expanded haemodialysis is an upgraded version of this standard process that uses special filters to remove larger waste products. Convective dialysis is a newer type of treatment. It uses a strong flow of water to push larger waste products out of the blood. There are three types of convective dialysis: 1) haemofiltration, which relies only on a strong water flow; 2) haemodiafiltration, which combines standard filtering with this strong water flow; and 3) acetate-free biofiltration, which is a form of haemodiafiltration that uses a special fluid to keep blood pressure stable. We compared these newer dialysis types with standard and expanded haemodialysis.
What did we want to find out?
We wanted to find out if convective dialysis is better or worse than standard haemodialysis for adults with kidney failure.
We wanted to know if convective dialysis reduces the risk of death from any cause and death from cardiovascular disease. We also wanted to see if it improves energy levels, reduces hospital stays, prevents problems with the blood access point, and improves the overall quality of life.
What did we do?
We searched for studies that compared convective dialysis with standard haemodialysis in adults with kidney failure.
We compared and summarised the results and rated our confidence in the evidence based on factors such as study methods and size.
What did we find?
We found 62 studies with a total of 6897 adult participants; 54 studies compared convective haemodialysis with standard haemodialysis (6525 adults). We compared the results across these studies to see which treatment was better.
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Compared to standard haemodialysis, convective dialysis probably reduces the risk of death from any cause as well as from heart or blood vessel disease.
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Convective dialysis probably results in little to no difference in nonfatal heart problems.
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Convective dialysis may result in little to no difference in severe tiredness, problems with the dialysis access point, hospital stays, or the overall quality of life.
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Direct comparisons between the different types of convective therapies were too small to show any meaningful differences.
What are the limitations of the evidence?
We are moderately confident in the results for the risk of death, risk of death from heart or blood vessel disease, and nonfatal heart problems. We are less confident in the results for severe tiredness, problems with the dialysis access point, hospital stays, and the overall quality of life. This is because some studies enrolled only a small number of adults or did not report these outcomes. The studies also used different treatment setups, making direct comparisons difficult. Future studies should focus on how these treatments affect the daily lives of adults living with kidney failure.
How up to date is this evidence?
The evidence is current to April 2025.
Read the full abstract
Background
Convective dialysis modalities (haemofiltration (HF), haemodiafiltration (HDF), and acetate-free biofiltration (AFB)) removed excess body fluid across the dialysis membrane with positive pressure and accumulated middle- and larger-size accumulated solutes more efficiently than haemodialysis (HD). This increased larger solute removal combined with use of ultra-pure dialysis fluid in convective dialysis is hypothesised to reduce the frequency and severity of symptoms during dialysis as well as improve clinical outcomes. Convective dialysis therapies (HDF and HF) are associated with lower mortality compared to diffusive therapy (HD) in observational studies. This is an update of a review first published in 2006.
Objectives
To determine the benefits and harms of convective (HF, HDF, or AFB) versus diffusive (HD) dialysis modalities, or expanded HD (HDx), in preventing all-cause and cardiovascular death, cardiovascular morbidity, fatigue, and vascular access problems in adults with kidney failure.
Search strategy
We searched the Cochrane Kidney and Transplant Specialised Register, CENTRAL, MEDLINE, Embase and two trial registers up to 3 April 2025. Additionally, handsearching of journals and conference abstract books was performed, and the references of the included studies were reviewed.
Selection criteria
We included randomised controlled trials comparing convective therapy (HF, HDF, AFB) with another convective therapy or diffusive therapy (HD) for treatment of ESKD.
Data collection and analysis
Two independent authors identified studies, extracted data and assessed study risk of bias. We summarised treatment effects using the random effects model. We reported results as a risk ratio (RR) for dichotomous outcomes and mean difference (MD) for continuous data together with 95% confidence intervals (CI). We assessed for heterogeneity using the Chi2 test and explored the amount of variation in treatment estimates beyond that expected by chance using the I2 statistic.
Main results
Twenty studies comprising 667 participants were included in the 2006 review. In that review, there was insufficient evidence of treatment effects on major clinical outcomes to draw clinically meaningful conclusions. Searching to February 2015 identified 40 eligible studies comprising 3483 participants overall. In total, 35 studies (4039 participants) compared HF, HDF or AFB with HD, three studies (54 participants) compared AFB with HDF, and three studies (129 participants) compared HDF with HF.
Risks of bias in all studies were generally high resulting in low confidence in estimated treatment effects. Convective dialysis had no significant effect on all-cause mortality (11 studies, 3396 participants: RR 0.87, 95% CI 0.72 to 1.05; I2 = 34%), but significantly reduced cardiovascular mortality (6 studies, 2889 participants: RR 0.75, 95% CI 0.61 to 0.92; I2 = 0%). One study reported no significant effect on rates of nonfatal cardiovascular events (714 participants: RR 1.14, 95% CI 0.86 to 1.50) and two studies showed no significant difference in hospitalisation (2 studies, 1688 participants: RR 1.23, 95% CI 0.93 to 1.63; I2 = 0%). One study reported rates of hypotension during dialysis were significantly reduced with convective therapy (906 participants: RR 0.72, 95% CI 0.66 to 0.80). Adverse events were not systematically evaluated in most studies and data for health-related quality of life were sparse. Convective therapies significantly reduced predialysis levels of B2 microglobulin (12 studies, 1813 participants: MD -5.55 mg/dL, 95% CI -9.11 to -1.98; I2 = 94%) and increased dialysis dose (Kt/V urea) (14 studies, 2022 participants: MD 0.07, 95% CI -0.00 to 0.14; I2 = 90%) compared to diffusive therapy, but results across studies were very heterogeneous. Sensitivity analyses limited to studies comparing HDF with HD showed very similar results. Directly comparative data for differing types of convective dialysis were insufficient to draw conclusions.
Studies had important risks of bias leading to low confidence in the summary estimates and were generally limited to patients who had adequate dialysis vascular access.
Authors' conclusions
Convective dialysis likely reduces all-cause and cardiovascular death. Effects on nonfatal cardiovascular events, fatigue, vascular access failure, and hospitalisation are inconclusive.
Future RCTs should prioritise methodological rigour and could focus on unresolved questions, including the impact of convective therapies on patient-centred outcomes such as symptom burden, HRQoL, functional status, and intradialytic tolerance, as well as investigating barriers to uptake, evaluating health system readiness, assessing cost-effectiveness, and identifying strategies to promote equitable access.
Funding
No specific funding.
Registration
Previous versions available via DOI: 10.1002/14651858.CD006258 and DOI: 10.1002/14651858.CD006258.pub2.
