Pre-dilution on-line haemofiltration vs low-flux haemodialysis: a randomized prospective study.

BACKGROUND Accumulation of larger molecular weight uraemic toxins molecules may have a negative effect on the cardiovascular and nutritional state of dialysis patients and influence uraemic symptomatology. Their clearance can be enhanced by the use of haemofiltration (HF). METHODS The effects of low-flux haemodialysis (HD) (ultrapure dialysate; polyamide membranes) and pre-dilution on-line HF (1:1 blood/substitution ratio; target filtration volume: 1.2 times body weight) on cardiovascular and nutritional parameters, interdialytic levels of uraemic toxins and quality of life (QOL; Laupacis questionnaire) were assessed during 1 year follow-up. Forty patients were randomized. RESULTS After 1 year, 27 patients were eligible for analysis (HF: 13 patients; HD: 14 patients). Left ventricular mass index did not change in the HF patients (127+/-33 --> 131+/-36 g/m(2) after 12 months) or in the HD group (135+/-34 --> 138+/-32 g/m(2)). Also, there were no changes in pulse wave velocity, and 48 h systolic and diastolic blood pressures. Lean body mass, assessed by dual-energy X-ray absorptiometry, increased in the HF group (44.8+/-8.9 --> 46.2+/-9.6 kg; P<0.05), but not in the HD group (49.4+/-9.2 --> 50.6+/-8.8 kg), although differences between groups were not significant. Insulin-like growth factor-1 levels remained stable in the HF patients, but decreased in the HD group (P<0.05 between groups). QOL for physical symptoms improved in the HF group (4.2+/-1.2 --> 5.0+/-1.1; P<0.05 within the HF group and P = 0.06 between groups), but not in the HD group (4.0+/-1.0 --> 4.4+/-1.4). beta2-microglobulin, complement factor D and homocysteine decreased significantly in the HF but not in the HD group, whereas l-ADMA, leptin and advanced glycation end-products-related fluorescence did not change. CONCLUSIONS No changes in cardiovascular parameters were observed during pre-dilution on-line HF compared with low-flux HD. Treatment with on-line HF resulted in marked changes in the uraemic toxicity profile, an improvement in physical well-being and a small improvement in nutritional state.