Sevelamer is an effective calcium-free phosphate binder, but widespread use of this agent is restricted by its considerable expense.OBJETIVE
To ascertain whether there is a more cost-effective way of prescribing sevelamer in patients on peritoneal dialysis than the current 'treat to goal' approach.DESIGN
Adults who were receiving peritoneal dialysis and had a serum calcium -phosphorus product >44.4 mmol2/l2 [>55 mg2/dl2])were recruited for this open-label study at the Prince of Wales Hospital in Hong Kong. Previous use of sevelamer was an exclusion criterion.INTERVENTION
Patients were randomized on a 1:2 basis to receive either 4.0g/day sevelamer (the maximum recommended dose) or a low dose of 1.2g/day, both given in divided doses with food. Use of vitamin D analogs and calcium-based or aluminum-based phosphate binders was not restricted. Follow-up continued for 6 months, with assessments at 4 weeks, 8 weeks and every 8 weeks thereafter.OUTCOME MEASURE
The primary end point was the proportion of patients whose serum calcium-phosphorus product declined to the National Kidney Foundation Kidney Disease Outcomes Quality Initiative (KDOQI) target of <4.4 mmol2/l2(<55 mg2/dl2).RESULTS
A total of 27 patients underwent randomization (9 to the conventional sevelamer dose;18 to the low dose);all were of Chinese ethnicity. The patients' mean age was 54 ± 14 years, and the mean baseline serum calcium-phosphorus product was 5.7 mmol2/l2 (71 mg2/dl2). There were no significant differences in demographic, clinical or laboratory characteristics between the two groups at baseline. The dose of phosphate binders did not change significantly in either group during the study. Adherence to sevelamer treatment was 90% in the conventional-dose group and 89%in the low-dose group. The incidence of adverse events (both overall and serious) was comparable in the two groups. During the 6 months of the study, serum calcium-phosphorus product declined significantly in the 4.0 g/day group, but not in the 1.2 g/day group (−1.9 mmol2/l2 [−23.5 mg2/dl2 ], P=0.003,and −0.3 mmol2/l2 [−3.7 mg2/dl2 ], P =0.28, respectively). Multivariate analysis identified only serum calcium-phosphorus product at 1 month as a predictor of sevelamer response at 6 months (P =0.006). After 6 months of sevelamer treatment, the difference in the primary end point between the patients randomized to the conventional sevelamer dose and those randomized to the low dose was not significant (66.7%vs 33.3%; P =0.10). The number of patients needed to treat to achieve the KDOQI target for serum calcium-phosphorus product in 1 individual would be 1.5 with 4.0 g/day sevelamer and 3 with 1.2 g/day sevelamer. Using a daily sevelamer dose of 1.2 g/day instead of 4.0 g/day would enable an extra 66.7%of patients to attain this target, at a saving of US$201 per patient for 6 months' treatment.CONCLUSION
Low-dose sevelamer treatment might control serum calcium-phosphorus product more cost-effectively than conventional dosing in patients on peritoneal dialysis.