Biocompatibility in haemodialysis: fact and fiction.

Several of the pro-inflammatory pathways that are activated in patients during dialysis have the potential of producing many side effects. These occur three times a week, accompanying dialysis, and are particularly intense in patients dialysed with so-called 'bioincompatible' membranes. Despite the proven biological superiority of biocompatible membranes, we lack definitive evidence that complement and cell activation three times a week over a period of years is detrimental to patients, because the results of prospective randomized studies are conflicting. Although they do not lead to a decrease in acute clinical symptoms, epidemiological studies suggest that semi-synthetic and synthetic membranes may reduce morbidity and mortality in dialysis patients. Further large scale, prospective and randomized trials with a long follow-up are needed in order to clarify the clinical effects of biocompatibility per se, the increasingly recognized clinical importance of high-flux treatments and the possible interaction between biocompatibility and membrane flux.