Analytical methods

In previous 28-week and 52-week studies of FC in Japanese haemodialysis patients with hyperphosphatemia¹², the mean (SD) change in the dose of ESAs from baseline to week 24 was—1045.6 (2579.0) IU/week. The intended sample size was estimated to be 90 patients in total to provide 83.3% power to detect the difference in mean changes in the dose of ESAs from baseline to the EOT between the FC and control groups with a type 1 error of 5% by the Wilcoxon rank sum test. Based on the full analysis set (FAS) data from the ASTRIO study (FC (n = 46), control (n = 45)), we analysed data for drug costs and RDW that were available at both baseline and EOT (FC (n = 40), control (n = 42)) for the cost-effectiveness analysis. Differences in changes in mean drug costs between the two groups were tested using Student’s t tests with a two-sided significance level of 0.05. Differences in changes in mean RDW between the two groups were tested by analysis of covariance with baseline values as covariates at a two-sided significance level of 0.05. We calculated the rate of achievement of an RDW < 15.5% using the FAS data (FC (n = 46), control (n = 45)) and analysed the differences between the groups using Fisher’s exact test at a two-sided significance level of 0.05. Statistical analyses were performed using SAS version 9.3 or version 9.4 (SAS Institute Inc., Cary, NC, USA).