Convective versus diffusive dialysis therapies for chronic kidney failure: An updated systematic review of randomized controlled trials

Background Convective dialysis therapies (hemofiltration or hemodiafiltration) are associated with lower mortality compared to hemodialysis in observational studies. A previous meta-analysis of randomized trials comparing convective modalities with hemodialysis in 2006 was inconclusive due to insufficient data. Additional randomized trials recently have reported conflicting results. Study Design Systematic review and meta-analysis of randomized trials to February 27, 2013. Setting & Population Patients with chronic kidney failure treated by hemodialysis, hemodiafiltration, hemofiltration, or biofiltration. Selection Criteria for Studies Randomized controlled trials. Intervention Convective therapies (hemodiafiltration, hemofiltration, and acetate-free biofiltration) compared with hemodialysis. Outcomes All-cause and cardiovascular mortality, nonfatal cardiovascular events, hospitalization, change in dialysis modality, health-related quality of life, adverse events, blood pressure, and clearances of urea and β₂- microglobulin. Results 35 trials (4,039 participants) were included. In low-quality evidence, convective dialysis had little or no effect on all-cause mortality (relative risk [RR], 0.87; 95% CI, 0.70-1.07) and may reduce cardiovascular mortality (RR, 0.75; 95% CI, 0.58-0.97) and hypotension (RR, 0.72; 95% CI, 0.66-0.80) during dialysis, but had uncertain effects on nonfatal cardiovascular events (RR, 1.14; 95% CI, 0.85-1.52) and hospitalization (RR, 1.21; 95% CI, 0.12-12.05). Adverse events were not reported systematically and health-related quality-of-life outcomes were sparse. Convective therapies reduced predialysis levels of β₂-microglobulin (mean difference, -5.77 [95% CI, -10.97 to -0.56] mg/dL) and increased dialysis dose (Kt/V _urea mean difference, 0.10; 95% CI, 0.02-0.19), but these effects were very heterogeneous. Sensitivity analyses limited to trials comparing hemodiafiltration with hemodialysis showed similar results. Limitations Studies had important risks of bias leading to low confidence in the summary estimates and generally were limited to patients who had adequate dialysis vascular access. Conclusions Treatment effects of convective dialysis are unreliable due to limitations in trial methods and reporting. Convective dialysis may reduce cardiovascular but not all-cause mortality, and effects on nonfatal cardiovascular events and hospitalization are inconclusive.