Do differences in dialysis prescription impact on KDOQI bone mineral targets? The Pan Thames Renal Audit

Background and Objectives: Patients achieving the Kidney Disease Outcomes Quality Initiative (KDOQI) bone mineral clinical practice guidelines have been reported to have improved survival. Many factors affecting calcium and phosphate control are not modifiable; however, we wished to determine whether differences in dialysis treatment could affect achievement of KDOQI clinical guideline targets. Methods: We audited pre-mid-week session calcium and phosphate levels in 5,324 adult patients receiving thrice weekly dialysis in the 14 Pan Thames centres: 60% male, mean age 62 ± 16 years, median dialysis vintage 29 months (14–58), 84% treated by haemodialysis, 16% by online haemodiafiltration, median session time 4.0 h (3.5–4.0). Results: Patients achieving the KDOQI guidelines varied between the centres: 23.4–60% for calcium, 31.7–56.7% for phosphate, 60–87.3% for calcium-phosphate product, 17.1–46.8% for parathyroid hormone (PTH) and 1.8–10.8% for all 4 targets. Those centres which used the highest dialysate calcium concentrations (1.5 mmol/l, 3 mEq/l) had more patients above the KDOQI serum calcium and more below the PTH target, than those centres using the lowest calcium dialysates (1 mmol/l, 2 mEq/l), with χ2 = 85.1 and χ2 = 52.4, p < 0.001, respectively. On logistic regression analysis, serum phosphate was negatively associated with duration of dialysis session time (F = 21.4, p = 0.000) and haemodiafiltration (F = 9.6, p = 0.000), respectively. Conclusions: Although many of the factors determining calcium and phosphate control in haemodialysis patients are unmodifiable, dialysate calcium concentration, the duration of the dialysis session and haemodiafiltration all had an impact on calcium, phosphate and PTH.