Eligible patients were then randomly assigned (1:1:1), either to continue on the previous same dose and route of administration of Epoetin alpha or beta (Epoetin group), or to receive Darbepoetin alfa (Aranesp ® Amgen) every week or 2weeks (Darbepoetin group) or methoxy polyethylene glycol-epoetin beta (Mircera ® Roche ,F. Hoffmann-La Roche, Basel, Switzerland) once monthly (C.E.R.A. group).