Effect of Dialysis Dose and Membrane Flux in Maintenance Hemodialysis

TLDR

The impact of dialysis dose and dialyzer membrane flux on mortality and morbidity in maintenance hemodialysis patients remains uncertain. This randomized clinical trial aimed to determine whether a higher dialysis dose or high‑flux membranes reduce mortality and morbidity in patients on thrice‑weekly hemodialysis. The study enrolled 1,846 patients in a 2×2 factorial design, assigning them to standard or high dose (mean urea‑reduction ratios 66.3 % vs 75.2 %) and low‑ or high‑flux membranes (beta‑2‑microglobulin clearance 3 mL/min vs 34 mL/min). Higher dialysis dose and high‑flux membranes did not significantly reduce all‑cause mortality or secondary outcomes, with relative risks of 0.96 and 0.92 respectively, indicating no major benefit in the overall cohort.

Abstract

The effects of the dose of dialysis and the level of flux of the dialyzer membrane on mortality and morbidity among patients undergoing maintenance hemodialysis are uncertain.We undertook a randomized clinical trial in 1846 patients undergoing thrice-weekly dialysis, using a two-by-two factorial design to assign patients randomly to a standard or high dose of dialysis and to a low-flux or high-flux dialyzer.In the standard-dose group, the mean (+/-SD) urea-reduction ratio was 66.3+/-2.5 percent, the single-pool Kt/V was 1.32+/-0.09, and the equilibrated Kt/V was 1.16+/-0.08; in the high-dose group, the values were 75.2+/-2.5 percent, 1.71+/-0.11, and 1.53+/-0.09, respectively. Flux, estimated on the basis of beta2-microglobulin clearance, was 3+/-7 ml per minute in the low-flux group and 34+/-11 ml per minute in the high-flux group. The primary outcome, death from any cause, was not significantly influenced by the dose or flux assignment: the relative risk of death in the high-dose group as compared with the standard-dose group was 0.96 (95 percent confidence interval, 0.84 to 1.10; P=0.53), and the relative risk of death in the high-flux group as compared with the low-flux group was 0.92 (95 percent confidence interval, 0.81 to 1.05; P=0.23). The main secondary outcomes (first hospitalization for cardiac causes or death from any cause, first hospitalization for infection or death from any cause, first 15 percent decrease in the serum albumin level or death from any cause, and all hospitalizations not related to vascular access) also did not differ significantly between either the dose groups or the flux groups. Possible benefits of the dose or flux interventions were suggested in two of seven prespecified subgroups of patients.Patients undergoing hemodialysis thrice weekly appear to have no major benefit from a higher dialysis dose than that recommended by current U.S. guidelines or from the use of a high-flux membrane.