Prevalence, clinical correlates and therapy cost of mineral abnormalities among haemodialysis patients: a cross-sectional multicentre study

Background. This study evaluated the proportion of patients who met National Kidney Foundation Kidney Disease Outcomes Quality Initiative (NKF-K/DOQI) guidelines for mineral status, and assessed the cost of therapy for mineral management of patients under haemodialysis treatment in Spain. Methods. Demographic and biochemical data were collected for 1312 patients undergoing standard three-times weekly maintenance haemodialysis at six Spanish centres during December 2003. Age, gender, diabetic nephropathy, haemodialysis duration, serum calcium, phosphorus, calcium-phosphorus product (Ca x P), and intact parathyroid hormone (iPTH) levels were monitored. Exploratory analyses of associations between demographic and biochemical parameters, were undertaken using bivariate and multivariate regression techniques. Results. Mean age of patients was 62 years. 97% were Caucasian, 23% were diabetic. In total, 51% of patients received calcium binders, 21% sevelamer, 16% aluminium hydroxide, and 29% received no binders; 33% of patients received calcitriol. Prevalence of patients outside K/DOQI targets was: calcium 50%, phosphorus 46%; Ca x P 33%; iPTH 77%. Elevated phosphorus (> 5.5 mg/dl) was independently associated with younger age [OR 0.972 (95% CI 0.963-0.980), P < 0.001] and higher iPTH [OR 1.0005 (95% CI 1.0002-1.0008), P < 0.001]. Elevated Ca x P (>= 55 mg(2) x dl(2)) showed a similar relationship. High iPTH levels (> 300 pmol/l) were associated with female gender [OR 1.574 (95% CI 1.213-2.041), P < 0.001], high serum phosphorus [OR 1.230 (95% CI 1.130-1.338), P < 0.001], and longer duration of dialysis [OR 1.003 (95% CI 1.001-1.005), P < 0.01]. Poorly controlled serum phosphorus, Ca x P and iPTH were associated with more expensive therapy for mineral management. Conclusions. One in three haemodialysis patients in Spain remains above the upper target range defined in current mineral metabolism guidelines. This abnormal profile is more common in younger patients and females and therapy is more expensive in younger patients.