title: Occurrence and determinants of poor response to short-term pre-operative erythropoietin treatment.
abstract: BACKGROUND
  This study aimed to explore the occurrence and determinants of poor response to short-term pre-operative erythropoietin treatment and the effect of such poor response on transfusion in total hip arthroplasty patients.
  
  
  METHODS
  We studied total hip arthroplasty patients who received erythropoietin before surgery. The primary outcome was the pre-operative increase in haemoglobin (delta haemoglobin) as response to erythropoietin therapy. Additionally, patients were classified in tertiles based on this delta haemoglobin: poor responders (cases), responders and good responders (controls) to erythropoietin. Patient characteristics, comedication and co-morbidity were collected as potential determinants of erythropoietin response. Regression techniques were used to estimate the strength of the associations and to assess the effect of poor response on transfusion requirement.
  
  
  RESULTS
  A total of 379 patients receiving erythropoietin were eligible to enter the study. Mean delta haemoglobin was 19.3 g/l (standard deviation 9.4). Factors significantly associated with delta haemoglobin were the use of angiotensin II antagonists [-3.1 g/l; 95% confidence interval (CI) -5.7 to -0.6] and vitamin K antagonists (-6.9 g/l; 95% CI -10.0 to -0.2), together with body mass index (BMI) (-0.3 g/l per unit>; 95% CI -0.5 to -0.2). The additional case-control analysis yielded comparable results. Poor response to erythropoietin was associated with an increased transfusion risk (odds ratio 4.6, 95% CI 2.0-11).
  
  
  CONCLUSIONS
  Use of angiotensin II receptor antagonists and vitamin K antagonists, and having a high BMI were determinants of poor response to short-term pre-operative erythropoietin treatment in total hip arthroplasty patients. Poor responders had a higher risk for perioperative blood transfusion.
authors.affiliation: Department of Clinical Pharmacy, Medical Center Alkmaar, Wilhelminalaan 12, Alkmaar, The Netherlands.
authors.forename: I M M
authors.initials: IM
authors.lastname: van Haelst
authors.forename: A C G
authors.initials: AC
authors.lastname: Egberts
authors.forename: H J
authors.initials: HJ
authors.lastname: Doodeman
authors.forename: W W
authors.initials: WW
authors.lastname: van Solinge
authors.forename: C J
authors.initials: CJ
authors.lastname: Kalkman
authors.forename: M
authors.initials: M
authors.lastname: Bennis
authors.forename: H S
authors.initials: HS
authors.lastname: Traast
authors.forename: W A
authors.initials: WA
authors.lastname: van Klei
mesh_terms: D000368:Aged; D000740:Anemia / Q000097:blood / Q000188:drug therapy*; D019644:Arthroplasty, Replacement, Hip; D001803:Blood Transfusion; D015897:Comorbidity; D003627:Data Interpretation, Statistical; D004921:Erythropoietin / Q000627:therapeutic use*; D005260:Female; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D008297:Male; D011300:Preoperative Care; D011994:Recombinant Proteins / Q000627:therapeutic use; D017211:Treatment Failure; D016896:Treatment Outcome
chemical_list: D006454:Hemoglobins; D011994:Recombinant Proteins; D004921:Erythropoietin