Haemodiafiltration, haemofiltration and haemodialysis for adults with kidney failure

RATIONALE: 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 METHODS: 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. ELIGIBILITY 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. OUTCOMES: Critical and important outcomes included all-cause and cardiovascular death, nonfatal cardiovascular events, fatigue, problems with vascular access, hospitalisation, and health-related quality of life (HRQoL). RISK OF BIAS: Two authors independently assessed the risk of bias using the Cochrane RoB 1 tool. SYNTHESIS METHODS: 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. INCLUDED STUDIES: 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. SYNTHESIS OF RESULTS: 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.