Haemodiafiltration vs Conventional Haemodialysis in Children (3H)

Background: Children on conventional haemodialysis (HD) have a 1000-fold higher mortality than their healthy peers and can have malnutrition and growth retardation. Haemodiafiltration (HDF) achieves better clearance of uraemic solutes across a wide molecular-weight range and performs greater ultrafiltration than conventional HD. Randomised controlled trials in adults have shown 35-45% improved survival and reduced cardiovascular mortality on HDF with high convection volumes. Excellent catch-up growth has been demonstrated in children on HDF, but mechanisms are poorly understood.

Hypothesis: HDF improves the cardiovascular risk profile, growth and quality of life (QoL) compared to conventional HD. Primary outcome measures are carotid intima-media thickness (cIMT) and height standard deviation score (SDS).

Plan of investigation: Incident and prevalent patients on HDF or HD who are expected to remain on dialysis for >6-months and who have a single pool Kt/v>1.2 will be compared in a 1:1 study design. Anthropometric measures (height SDS, body mass index SDS) and QoL questionnaires will be monitored at baseline and 6-monthly. Cardiovascular measures (cIMT, pulse wave velocity, left ventricular mass index and 24-hour BP) will be measured annually. 6-monthly blood tests will measure nutritional biomarkers, mineral dysregulation, inflammation and middle-molecule clearance. Outcome measures will be standardised to the convective clearance dose per m2 body surface area. Recruitment will continue for 2½ years with minimum follow-up of 6-months.

Children will be recruited from all UK dialysis units, but small patient numbers (10-12/year) necessitate collaborations with European centres. HDF and HD patients across Europe who are part of the Cardiovascular Comorbidity in Childhood CKD (4C) study will be included and vascular scans will be captured from this study. From ESPN/ERA-EDTA registry data we estimate ~100 children on HDF over the study period.

Outcomes: If the 3H (HDF-Hearts-Height) study shows that HDF reduces cardiovascular morbidity and improves growth it may lead to HDF being adopted as the standard for in-centre dialysis.