Comparison of Pre- vs Post-dilution Haemodiafiltration in Children

Hypothesis: In children with end stage kidney disease pre-dilution HDF (pre-HDF) achieves improved clearances across a wide molecular weight range compared to post-dilution HDF (post-HDF).

Plan of Investigation: Prevalent patients on thrice weekly HD or HDF who have a single pool Kt/v>1.2 will be randomized in to either study arm A (pre-HDF, post-HDF) or B (post-HDF, pre-HDF) after a conditioning period on post-HDF. Dialysis prescription will be kept constant during study periods including blood flow, dialysate flow, dialysate content, filter type and size. Pre-dialysis and post-dialysis bloods will be drawn at baseline and at the end of each treatment with either modality. Reduction ratios of small and middle molecular weight toxins and protein bound toxins as well as markers of inflammation and nutrition will be compared between two modalities. Assessment of blood pressure (ambulatory blood pressure monitoring) and patient wellbeing (questionnaire) will be performed at the end of each period.

Children will be recruited from paediatric dialysis units in London, Istanbul Heidelberg and Lyon with extension to other centres to be confirmed.

Outcomes: If the results of this study demonstrate better clearance with pre-dilution HDF compared to post-dilution HDF, this will inform a future long-term outcome study comparing different HDF modalities and will contribute to define optimum dialysis modality for children.