Prospective randomized cross-over long-term comparison of online haemodiafiltration and ultrapure high-flux haemodialysis.

BACKGROUND The residual uraemic syndrome that is inadequately cleared by diffusion is thought to contribute to the poor outcome of maintenance dialysis patients. Haemodiafiltration combines diffusion and convection in a single therapy, conferring theoretical benefits over haemodialysis. However, only few randomised comparisons have been carried out. METHODS The prospective crossover clinical evaluation of high-flux ultrapure haemodialysis and online haemodiafiltration included 76 clinically stable patients on low-flux conventional bicarbonate buffered haemodialysis. They were randomized to high-flux haemodialysis or online haemodiafiltration (24 months) and switched to the alternative treatment (24 months). RESULTS Removal of urea (Kt/V) and phosphate was significantly greater for online haemodiafiltration than for haemodialysis. Both high-flux haemodialysis and haemodiafiltration were associated with sustained reductions of pretreatment beta 2 microglobulin levels, however, the decrease was greater with haemodiafiltration. Both modes of renal replacement therapy significantly improved nutritional status and the haematopoietic response to rHu EPO. Under unmatched conditions (sodium and energy balance) haemodiafiltration was associated with a lower number of hypotensive episodes and partial improvement of quality of life. The incidence of death was low in both groups and did not differ among the two modes of renal replacement therapy. CONCLUSION Online haemodiafiltration is a safe, effective and well tolerated therapy for end-stage renal disease patients even in the long run. Whether the dismal mortality rates of unselected end-stage renal disease patients can be changed by online haemodiafiltration remains to be shown in large scale long-term trials.