title: [Evolution of the darbepoetin alpha resistance index in patients on dialysis who change from weekly to fortnightly treatments in clinical practice].
abstract: BACKGROUND
  Darbepoetin alpha (DA) administered every-other-week (Q2W) is efficacious and safe for the treatment of anaemia in patients undergoing dialysis. There are no data available regarding the evolution of erythropoietic resistance index (ERI) after conversion from weekly (QW) to Q2W administration of DA in clinical practice.
  
  
  METHODS
  Multicenter, observational, retrospective, 16-weeks study, which included stable patients undergoing dialysis who were converted from DA QW to DA Q2W in clinical practice. Conversion was done according to product specifications (duplicating QW dose). The ERI to DA was calculated by dividing the weekly DA dose per kilogram of weight (microg/wk.kg)*200 by the Hb level (g/dL). ERI evolution with time was evaluated by multivariate repeated measures ANOVA, adjusting for significant covariates.
  
  
  RESULTS
  A total of 202 patients were included (137 patients undergoing haemodialysis [HD], intravenous (IV) DA, and 65 patients receiving peritoneal dialysis [PD], subcutaneous DA). Mean (SD) age was 66 (17) years; 61% of patients were men. Large intercentre variability was observed for the ERI at conversion time (coefficient of variation of 88%, p < 0.001 for differences between centres). In the univariate analysis, predictor factors for high baseline ERI were low albumin level (r = -0.29; p =0.001), HD (mean ERI of 9.3 [8.4] vs 6.8 [4.6] for PD; p = 0.005), or previous cardiovascular disease (9.9 [8.7] vs 7.4 [6.3] for patients without history; p =0.025). During the follow up, the ERI was slightly increased in HD patients (9.3 [8.4] at conversion vs 11.1 [7.3] at 16 weeks; p < 0.05), and remained stable in PD patients (6.8 [4.6] vs 6.7 [4.0], respectively; NS). In the multivariate analysis, there were no significant differences in ERI during the 16 weeks post-conversion after adjusting for albumin levels and centre (adjusted baseline mean [95% CI] of 10.0 [8.7-11.4] vs 10.5 [9.3-11.8] at 16 weeks, adjusted change of +0.5 [-0.67; 1.67]; NS). After 16 weeks, only 7 patients (3.5%) had discontinued Q2W administration.
  
  
  CONCLUSIONS
  Extension from weekly to once every other-week darbepoetin alpha allows to simplify anaemia treatment without increasing the resistance index, regardless of dialysis type. The multivariate analysis shows that, after adjusting by center and inflammation/nutritional status, there were no changes in the response to darbepoetin alpha during the first 16 weeks after conversion in clinical practice.
authors.affiliation: Servicios de Nefrología, Hospital Gregorio Marañón, Madrid, Spain. juanmlopez@senefro.org
authors.forename: J M
authors.initials: JM
authors.lastname: López-Gómez
authors.forename: A L Martín
authors.initials: AL
authors.lastname: de Francisco
authors.forename: J
authors.initials: J
authors.lastname: Montenegro
authors.forename: C
authors.initials: C
authors.lastname: de Santiago
authors.forename: M
authors.initials: M
authors.lastname: Vera
authors.forename: C
authors.initials: C
authors.lastname: Donapetry
authors.forename: M
authors.initials: M
authors.lastname: Villaverde
mesh_terms: D000368:Aged; D000740:Anemia / Q000188:drug therapy*; D000068256:Darbepoetin alfa; D004334:Drug Administration Schedule; D004351:Drug Resistance; D004921:Erythropoietin / Q000008:administration & dosage / Q000031:analogs & derivatives*; D005260:Female; D006397:Hematinics / Q000008:administration & dosage*; D006801:Humans; D008297:Male; D006435:Renal Dialysis; D012189:Retrospective Studies
chemical_list: D006397:Hematinics; D004921:Erythropoietin; D000068256:Darbepoetin alfa