Importance of ultrapure dialysis liquid in response to the treatment of renal anaemia with darbepoetin in patients receiving haemodialysis

Chronic inflammatory diseases and infections are a major cause of hyporesponse to erythropoiesis-stimulating factors. We conducted this prospective study in 107 patients in haemodialysis with dialysis liquid that was potentially contaminated from a bacteriological perspective in order to test the hypothesis that ultrapure dialysis liquid can improve the response to treatment with darbepoetin and reduce inflammatory markers. These patients had to have been stable in the last 8 weeks in relation to haemoglobin level and the administered dose of darbepoetin. Two filters (one of hydrophilic nylon and another of polysulfone) were added to the water treatment process, the first one prior to distribution ring output and the second before the dialyser. The patients were evaluated for 12 months. The dosage of darbepoetin was varied to maintain haemoglobin levels ranging from 11 to 14 g/dl. We measured resistance to the erythropoiesis-stimulating factor, defined as the quotient between weekly dose of darbepoetin and haemoglobin levels, baseline and every two months, the baseline and monthly endotoxin count and reactive protein C at baseline and every 6 months. 94 patients completed the study. The resistance index fell significantly during follow-up (p<0.001) and was measurable from the second month on. Haemoglobin levels remained within the established margins with a 34% reduction in the weekly dose of darbepoetin at the end of the follow-up period. Both reactive protein C and the endotoxin count were significantly reduced (p<0.001) compared to baseline after 6 and 12 months. To conclude, the bacteriological purity of the dialysis liquid reduces inflammatory markers in patients receiving haemodialysis, improving the response to treatment with darbepoetin in renal anaemia.