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

Abstract

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/Vurea 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.

Keywords: End-stage kidney disease; dialysis; hemodiafiltration; meta-analysis; systematic review.