Key messages
- 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.
- 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.
- 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.
- Compared to standard haemodialysis, convective dialysis probably reduces the risk of death from any cause as well as from heart or blood vessel disease.
- Convective dialysis probably results in little to no difference in nonfatal heart problems.
- 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.
- 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 extracorporeal dialysis modalities, haemofiltration (HF), haemodiafiltration (HDF), and acetate‐free biofiltration (AFB), remove excess body fluid across the dialysis membrane through an interplay of positive and negative pressures and accumulated middle‐ and larger‐sized solutes more efficiently than haemodialysis (HD). This increased removal of larger solutes, combined with the use of ultrapure dialysis fluid in convective dialysis, is hypothesised to reduce the frequency and severity of symptoms during HD and improve long‐term clinical outcomes. This is an update of a review first published in 2006 and updated in 2015.
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 (RCTs) comparing convective therapy (HF, HDF, AFB) with another convective therapy or with diffusive therapy (HD or HDx) for treating adults with kidney failure.
Data collection and analysis
Two authors independently assessed the risk of bias using the Cochrane RoB 1 tool.
Main results
We summarised treatment effects using the random‐effects model and reported risk ratios (RR) for dichotomous outcomes and mean differences (MD) for continuous data with 95% confidence intervals (CI). We assessed the confidence of the evidence using the GRADE approach.
We identified 62 eligible studies (6897 participants). In total, 54 studies (6525 participants) compared HF, HDF or AFB with HD (both high‐flux and low‐flux); two studies (24 participants) compared AFB with HDF; three studies (62 participants) compared HDF with HF; and four studies (163 participants) compared HDx with HDF/HD.
Convective dialysis, compared with diffusive therapy, likely reduces the risk of death (any cause) (RR 0.88, 95% CI 0.80 to 0.96; I² = 0%; 15 studies, 5463 participantss; moderate‐certainty evidence due to indirectness) and cardiovascular death (RR 0.78, 95% CI 0.66 to 0.92; I² = 0%; 9 studies, 4761 participants; moderate‐certainty evidence due to indirectness). Cardiovascular morbidity was likely not different between convective and diffusive dialysis (RR 1.05, 95% CI 0.90 to 1.22; I² = 0%; 2 studies, 2074 participants; moderate‐certainty evidence due to indirectness). Little to no differences were found between convective and diffusive dialysis on fatigue (MD −0.95, 95% CI −2.50 to 0.60; 1 study, 543 participants; low‐certainty evidence due to imprecision), problems with vascular access (RR 0.87, 95% CI 0.50 to 1.50; 1 study, 124 participants; low‐certainty evidence due to imprecision), hospitalisation (RR 1.14, 95% CI 0.96 to 1.37; I² = 0%; 3 studies, 600 participants; low‐certainty evidence due to indirectness and imprecision), or physical quality of life (MD 0.66, 95% CI −1.08 to 2.40; 1 study, 538 participants; low‐certainty evidence due to imprecision).
Direct comparisons between different convective modalities were limited and underpowered to detect meaningful differences.
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.
