Data collection
Demographic data, medical history, dialysis prescriptions, and clinical and laboratory data were collected using a case report form. The laboratory data collected included serum levels of phosphorus, calcium, Ca × P product (every 2 weeks), iPTH, FGF23 (every 4 weeks), vitamin D-related parameters (every 8 weeks), sodium, and bicarbonate. Patients collected daily and weekly information on stool frequency and stool characteristics per the BSFS score in a patient diary. Patient-reported outcomes were evaluated every 8 weeks.