title: Association of fluid retention with anemia and clinical outcomes among patients with chronic kidney disease.
abstract: BACKGROUND
  Observational studies have demonstrated an association between anemia and adverse outcomes in patients with chronic kidney disease (CKD). However, randomized trials failed to identify a benefit of higher hemoglobin concentrations, suggesting that the anemia-outcome association may be confounded by unknown factors.
  
  
  RESULTS
  We evaluated the influence of fluid status on hemoglobin concentrations and the cardiovascular and renal outcomes in a prospective cohort of 326 patients with stage 3 to 5 CKD. Fluid status, as defined by overhydration (OH) level measured with bioimpedance, was negatively correlated with hemoglobin concentrations at baseline (r=-0.438, P<0.001). In multivariate regression analysis, OH remained an independent predictor of hemoglobin, second only to estimated glomerular filtration rate. Patients were stratified into 3 groups: no anemia (n=105), true anemia (n=82), and anemia with excess OH (n=139) (relative OH level ≥7%, the 90th percentile for the healthy population). During a median follow-up of 2.2 years, there was no difference in cardiovascular and renal risks between patients with true anemia and those with no anemia in the adjusted Cox proportional hazards models. However, patients with anemia with excess OH had a significantly increased risk of cardiovascular morbidity and mortality and CKD progression relative to those with true anemia and those with no anemia, respectively.
  
  
  CONCLUSIONS
  Fluid retention is associated with the severity of anemia and adverse cardiovascular and renal outcomes in patients with CKD. Further research is warranted to clarify whether the correction of fluid retention, instead of increasing erythropoiesis, would improve outcomes of CKD-associated anemia.
authors.affiliation: Division of Nephrology, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei City, Taiwan (S.C.H., K.L.K., C.H.P., C.H.W., Y.C.W.) School of Medicine, Tzu Chi University, Hualien, Taiwan (S.C.H., K.L.K., C.H.P., C.H.W., Y.C.W.).
authors.forename: Szu-Chun
authors.initials: SC
authors.lastname: Hung
authors.affiliation: Division of Nephrology, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei City, Taiwan (S.C.H., K.L.K., C.H.P., C.H.W., Y.C.W.) School of Medicine, Tzu Chi University, Hualien, Taiwan (S.C.H., K.L.K., C.H.P., C.H.W., Y.C.W.).
authors.forename: Ko-Lin
authors.initials: KL
authors.lastname: Kuo
authors.affiliation: Division of Nephrology, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei City, Taiwan (S.C.H., K.L.K., C.H.P., C.H.W., Y.C.W.) School of Medicine, Tzu Chi University, Hualien, Taiwan (S.C.H., K.L.K., C.H.P., C.H.W., Y.C.W.).
authors.forename: Ching-Hsiu
authors.initials: CH
authors.lastname: Peng
authors.affiliation: Division of Nephrology, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei City, Taiwan (S.C.H., K.L.K., C.H.P., C.H.W., Y.C.W.) School of Medicine, Tzu Chi University, Hualien, Taiwan (S.C.H., K.L.K., C.H.P., C.H.W., Y.C.W.).
authors.forename: Che-Hsiung
authors.initials: CH
authors.lastname: Wu
authors.affiliation: Division of Nephrology, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei City, Taiwan (S.C.H., K.L.K., C.H.P., C.H.W., Y.C.W.) School of Medicine, Tzu Chi University, Hualien, Taiwan (S.C.H., K.L.K., C.H.P., C.H.W., Y.C.W.).
authors.forename: Yi-Chun
authors.initials: YC
authors.lastname: Wang
authors.affiliation: Institutes of Physiology and Clinical Medicine, National Yang-Ming University, Taipei, Taiwan (D.C.T.) Division of Nephrology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan (D.C.T.).
authors.forename: Der-Cherng
authors.initials: DC
authors.lastname: Tarng
mesh_terms: D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D000740:Anemia / Q000175:diagnosis / Q000453:epidemiology* / Q000628:therapy; D015331:Cohort Studies; D015897:Comorbidity; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate / Q000502:physiology; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D015994:Incidence; D007676:Kidney Failure, Chronic / Q000175:diagnosis / Q000453:epidemiology* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016016:Proportional Hazards Models; D011446:Prospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D017678:Sex Distribution; D016896:Treatment Outcome; D014883:Water-Electrolyte Imbalance / Q000175:diagnosis / Q000453:epidemiology* / Q000628:therapy
chemical_list: D006454:Hemoglobins
keywords: anemia; bioimpedance; cardiovascular; kidney; overhydration