In this 12-week crossover study, patients (n=182) were randomized to receive either Fosrenol or sevelamer for four weeks, and then switched to the alternative phosphate binder for the same period. Product doses were pre-defined to allow a direct efficacy comparison. Doses were based on those used in previous clinical trials and established clinical practice.
The study's primary endpoint, change in serum phosphorus from baseline to end of treatment, was evaluated using several statistical analyses; the primary analysis used last observation carried forward (LOCF) for the intention to treat (ITT) population (n=174), meaning that if a patient dropped out of the study during treatment, their last post baseline serum phosphorus measurement was used as the end of treatment value. The pre-determined key secondary analysis assessed the completer population; defined as those patients who had completed four weeks' treatment with both phosphate binders and had a serum phosphorus value at the end of treatment.
The analysis of LOCF for the ITT population showed a numerically greater reduction in serum phosphorus with Fosrenol (1.7mg/dL) versus sevelamer (1.4mg/dL), although this did not reach statistical significance (p=0.113). In the completer population (n=119), considered to be the most clinically relevant population, Fosrenol reduced serum phosphorus by 1.8mg/dL, compared with 1.3mg/dL for sevelamer, a statistically significant difference (p=0.007). A statistically significant difference was also observed between the treatments at week 1 (p=0.024).
Study investigators concluded that the statistically larger reduction within the completer group suggested that Fosrenol may offer greater serum phosphorus reduction in CKD patients on hemodialysis.
"This study is important, because up until now, there was no data comparing the relative efficacies of lanthanum carbonate and sevelamer," said lead investigator Professor Stuart Sprague of Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA.
"The findings suggest that over four weeks of treatment, Fosrenol may be a more effective binder of phosphate. Further research is now required to evaluate whether the trends observed in this crossover study are continued in the long term," he added.
Current clinical guidelines recommend targets for phosphorus and other biochemical values including calcium and parathyroid hormone (PTH) in patients with CKD undergoing dialysis.