Biochemical comparison of 8-hour haemodialysis and 4-hour haemodiafiltration, and two dialysis membranes.

Abstract

Aim: To compare biochemical clearances with extended-hours haemodialysis (HD) and haemodiafiltration (HDF) and Fresenius FX80 (FX) and Nipro Elisio (NE) dialysers. Background(s): Extended-hours HD has long been regarded as the optimal form of dialysis for solute clearance. With emerging benefits of HDF, it would be prudent to compare these two head-to-head. Method(s): This is a randomized cross-over trial comparing 8-hours HD to 4-hours HDF. 12 NHD patients underwent a baseline 8-hour HD session, and then randomized to either 2 weeks of 8-hour HD or 4-hour HDF with crossover to the alternative treatment after a 2-week washout period. Subjects were additionally randomized to the NE or FX dialyser in a parallel design. Blood and dialysate samples were collected at baseline and at the end of both study periods. Result(s): Mean (SD) age and BMI were 55.1 +/-11.5 years and 36.4 +/-10.8 respectively. Blood flow (Qb) for HD was 250ml/min and dialysate flow (Qd) 300ml/min. For HDF, Qb was 300ml/min and Qd 500ml/min with mean convection rate 86.1ml/min (20.7 L/session). Urea and creatinine reduction ratios were higher with HD compared to HDF (difference 14.0%, 95% CI 10.6,17.3, p<0.001 & 9.1% 95% CI 11.0,7.2, p<0.001). Fibroblast growth factor 23 (FGF23) clearance was superior with HDF (difference 20.1%, 95% CI 8.7,31.6, p=0.001). No difference was seen in reduction ratios for phosphate, retinol binding protein, alpha-1-microglobulin, beta-2-microglobulin (B2M) and fetuin with both modalities. Compared to NE, FX dialyser achieved higher beta-2-microglobulin clearance (Period 1: difference 7.8%, 95% CI 1.3, 14.4, P=0.02, Period 2: 7.5%, 95%CI 1.0, 14.1, p=0.02). Conclusion(s): Small solute clearance was superior with extended-hours HD while HDF enhanced FGF23 clearance. B2M clearance was improved with Fresenius FX80 dialyser.