HPM (high-performance membrane or high-flux membrane) has better biocompatibility and higher capacity to remove retention solutes of large molecular weight, which has been proven to be toxic especially to cardiovascular and skeletal organs. To date, several non-randomized observational studies have shown a reduction in morbidity and mortality in HPM-treated patients compared with low-flux conventional membrane. Meanwhile, two randomized controlled trials were unable to reveal the superiority of high-flux membrane in survival of all-cause mortality, but suggested a significant benefit by subgroup analyses or post-hoc analyses in patients with diabetes, hypoalbuminemia and long duration of prior dialysis. Thus, the results of the published studies are conflicting and it still cannot be explained whether the effect is based on the biocompatibility of the membrane or on the differences in the clearance of middle molecules, or on the microbiological purity of dialysate which improved simultaneously with the flux increment. As survival outcome might be determined by additional multiple confounding factors, dialysis-related or non-dialysis-related, investigations to control them are difficult to perform. Although the clinical results are non-conclusive and it is still unanswered how much large molecule removal is required to improve outcomes in routine clinical practice, there is a considerable amount of biological plausibility for high-flux dialysis or middle molecule removal. Further trials will be required to confirm what patient group benefits the most, the magnitude of advantages and how large the molecules are and how much molecule removal is acceptable using advanced high-performance dialyzers. Dispersing hazardous effects by a low-quality therapy should be taken more seriously than practicing a high-quality therapy of uncertain superiority.
Copyright © 2011 S. Karger AG, Basel.