It decreased mortality by 37% compared with low-flux hemodialysis.
High-flux hemodialysis confers a definite survival advantage in high-risk patients compared with low-flux hemodialysis, according to results from a long-term, prospective trial presented here for the first time.
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The Membrane Permeability on ESRD Patient Outcome (MPO) study was designed to compare all-cause mortality among a total of 738 patients, with a majority with a baseline serum albumin of 4 gm/dL or less randomly assigned to hemodialysis using either a high-flux or a low-flux membrane. To exclude the potential for confounding re-sults by inadequate dialysis dose, Kt/V was regularly controlled and treatment parameters adjusted to achieve a minimum Kt/V of 1.2.
At the end of seven years follow-up, investigators observed a significant 37% relative risk reduction in all-cause mortality among patients undergoing high-flux hemodialysis (7.3%) compared with those in the low-flux group (10.4%).
“Results were even more impressive in the diabetic subgroup,” said principle investigator Francesco Locatelli, MD, FRCP, chief of the department of nephrology and dialysis at A. Manzoni Hospital in Lecco, Italy. He also is professor of nephrology at the University of Brescia and the University of Milan.
Among diabetics, the high-flux membrane group had a significantly greater survival advantage over the low-flux membrane group. In contrast, Prof. Locatelli and his colleagues observed no significant differences between the high and low-flux groups in all-cause hospitalizations or hospitalizations for infection or vascular access complications. Renal function was not significantly better preserved in the high-flux group.
Data from the Dialysis Outcomes Practice Patterns Study database suggest that approximately 60% of hemodialysis patients across Europe have levels of serum albumin of 4 g/dL or less, Prof. Locatelli noted. “Thus, results from MPO should be easily applicable to more than 60% of the general hemodialysis population,” he said, adding that after seven years of follow-up, “we are very happy to have a positive result.”
Investigators noted that diabetes is becoming an increasingly important cause of ESRD also in European patients, and now accounts for ap-proximately 30% of ESRD starting dialysis. Thus, they predicted that the MPO finding in the diabetic subgroup would have an important im-pact on ESRD treatment in diabetic patients as this segment of the population continues to grow.
As to why high-flux membranes might lead to improved survival, Raymond Vanholder, MD, professor of medicine at the University of Ghent in Belgium, explained that both high and low-flux membranes remove smaller molecules such as urea, but many of these toxins are not that biologically active.
Toxins with a larger molecular weight, however, have been implicated in the high CVD risk seen in hemodialysis patients. Therefore, it appears to be “quite logical” that removal of these large molecule toxins “are doing something very positive for these patients,” Prof. Vanholder said.
