title: Association of Erythropoietin Resistance with Fatigue in Hemodialysis Patients: A Cross-Sectional Study.
abstract: OBJECTIVE
  Fatigue is a common symptom in patients receiving hemodialysis (HD) and is generally associated with anemia. However, it can be difficult to resolve, even when anemia has been treated using erythropoiesis-stimulating agents and iron replacement therapy. In the present study, we examined the associations of anemia, the erythropoietin resistance index (ERI) and iron deficiency with fatigue during HD.
  
  
  METHODS
  In this cross-sectional study, fatigue score was calculated on the basis of questionnaire responses in HD patients. Participants were divided into 3 groups according to their hemoglobin (Hb) levels (low, normal and high). Iron deficiency was assessed as a transferrin saturation (TSAT) of <20%.
  
  
  RESULTS
  We included 571 HD patients (men/women 368/203; mean age 62.2 ± 10.8 years). Among the 3 groups, fatigue scores increased significantly with decreasing Hb levels. HD patients with low Hb levels (<90 g/l) had significantly higher fatigue scores than those with higher Hb levels (≥120 g/l). In the multiple regression analysis, we showed that a high ERI (β = 0.208) and a low TSAT (β = -0.155), but not the Hb level, were significantly associated with increased fatigue score. Moreover, this was independent of age, gender and modifiable confounders linked to anemia. Even after restricting patients to those without iron deficiency (TSAT ≥20%), the ERI (β = 0.258) retained a significant and independent association with the fatigue score.
  
  
  CONCLUSIONS
  Iron deficiency and a high ERI despite iron sufficiency may cause fatigue in HD patients.
authors.affiliation: Department of Metabolism, Endocrinology and Molecular Medicine, Osaka City University Graduate School of Medicine, Osaka, Japan.
authors.forename: Akiyo
authors.initials: A
authors.lastname: Yamasaki
authors.forename: Koichiro
authors.initials: K
authors.lastname: Yoda
authors.forename: Hidenori
authors.initials: H
authors.lastname: Koyama
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Yamada
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Tsujimoto
authors.forename: Senji
authors.initials: S
authors.lastname: Okuno
authors.forename: Shigeki
authors.initials: S
authors.lastname: Okada
authors.forename: Masaaki
authors.initials: M
authors.lastname: Inaba
mesh_terms: D000368:Aged; D003430:Cross-Sectional Studies; D004921:Erythropoietin / Q000009:adverse effects*; D005221:Fatigue / Q000139:chemically induced*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D006435:Renal Dialysis
chemical_list: D004921:Erythropoietin