title: Dose conversion ratio in hemodialysis patients switched from darbepoetin alfa to PEG-epoetin beta: AFFIRM study.
abstract: BACKGROUND
  There is limited information published on switching erythropoiesis-stimulating agent (ESA) treatment for anemia associated with chronic kidney disease (CKD) from darbepoetin alfa (DA) to methoxy polyethylene glycol-epoetin beta (PEG-Epo) outside the protocol of interventional clinical studies. AFFIRM (Aranesp Efficiency Relative to Mircera) was a retrospective, multi-site, observational study designed to estimate the population mean maintenance dose conversion ratio [DCR; dose ratio achieving comparable hemoglobin level (Hb) between two evaluation periods] in European hemodialysis patients whose treatment was switched from DA to PEG-Epo.
  
  
  METHODS
  Eligible patients had received hemodialysis for ≥ 12 months and DA for ≥ 7 months. Data were collected from 7 months before until 7 months after switching treatment. DCR was calculated for patients with Hb and ESA data available in both evaluation periods (EP; Months 1 and 2 were defined as the pre-switch EP, and Months 6 and 7 as the post-switch EP). Red blood cell transfusions pre- and post-switch were quantified.
  
  
  RESULTS
  Of 302 patients enrolled, 206 had data available for DCR analysis. The geometric mean DCR was 1.17 (95% CI 1.05, 1.29). Regression analysis indicated a non-linear relationship between pre- and post-switch ESA doses; DCR decreased with increasing pre-switch DA dose. The geometric mean weekly ESA doses were 24.1 μg DA in the pre-switch EP and 28.6 μg PEG-Epo in the post-switch EP. Mean Hb was 11.5 g/dL in the pre-switch EP and 11.4 g/dL in the post-switch EP. There were 16 transfusions and 34 units transfused in the pre-switch period, versus 48 transfusions and 95 units transfused post-switch. Excluding patients receiving a transfusion within 90 days of or during either EP, the DCR was 1.21 (95% CI 1.09, 1.35).
  
  
  CONCLUSIONS
  In these hemodialysis patients switched from DA to PEG-Epo the DCR was 1.17 and 1.21 after accounting for the effect of transfusions. The number of transfusions and units transfused increased approximately threefold from the pre-switch to the post-switch period.
authors.affiliation: Department of Nephrology, John Hunter Hospital, Lookout Road, New Lambton Heights, NSW, 2305, Australia, peter.choi@hnehealth.nsw.gov.au.
authors.forename: Peter
authors.initials: P
authors.lastname: Choi
authors.forename: Mourad
authors.initials: M
authors.lastname: Farouk
authors.forename: Nick
authors.initials: N
authors.lastname: Manamley
authors.forename: Janet
authors.initials: J
authors.lastname: Addison
mesh_terms: D000328:Adult; D000368:Aged; D000740:Anemia / Q000188:drug therapy* / Q000209:etiology; D015331:Cohort Studies; D000068256:Darbepoetin alfa; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D004921:Erythropoietin / Q000031:analogs & derivatives* / Q000627:therapeutic use; D005260:Female; D005500:Follow-Up Studies; D006397:Hematinics / Q000627:therapeutic use*; D006801:Humans; D007676:Kidney Failure, Chronic / Q000175:diagnosis / Q000628:therapy*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011994:Recombinant Proteins / Q000627:therapeutic use; D006435:Renal Dialysis / Q000009:adverse effects* / Q000379:methods; D012189:Retrospective Studies; D018570:Risk Assessment; D016896:Treatment Outcome
chemical_list: D006397:Hematinics; D011994:Recombinant Proteins; C103998:epoetin beta; D004921:Erythropoietin; D000068256:Darbepoetin alfa