The effect of dialysis modality on phosphate control : haemodialysis compared to haemodiafiltration. The Pan Thames Renal Audit.

BACKGROUND AND OBJECTIVES Hyperphosphataemia is a primary risk factor for patients with end-stage kidney failure. Phosphate clearance by traditional thrice-weekly standard haemodialysis is inadequate for patients achieving recommended dietary protein goals. We investigated whether phosphate control was improved by adding convective clearance with haemodiafiltration. METHODS We audited pre-midweek session calcium and phosphate levels in 5366 adult patients, 4515 treated by haemodialysis and 851 by on-line haemodiafiltration. RESULTS The cohorts were similar for age, sex and dialysis vintage. Serum phosphate was lower in the haemodiafiltration cohort (1.42 +/- 0.61 mmol/l) compared to the haemodialysis cohort (1.53 +/- 0.53 mmol/l; P < 0.001), as was the calcium-phosphate product (3.31 +/- 1.53 vs 3.5 +/- 1.33 mmol(2)/l(2), respectively; P < 0.001) despite a shorter treatment session time (3.68 +/- 0.44 vs 3.92 +/- 0.49 h; P < 0.001). Parathyroid hormone levels were similar. CONCLUSIONS The results of this audit suggest that haemodiafiltration offers improved phosphate control compared to standard intermittent haemodialysis.