title: Interactions between dialysis-related volume exposures, nutritional surrogates and mortality among ESRD patients.
abstract: BACKGROUND
  Interdialytic weight gain is used as a surrogate for volume expansion in haemodialysis patients and as an indicator of non-compliance. Increased weight gain is associated with both a greater mortality risk and better nutrition indices. This analysis characterizes the association between dialysis-related volume expansion and mortality in the context of its interaction with nutritional surrogates.
  
  
  METHODS
  All patients receiving haemodialysis through Fresenius Medical Care-North America during 1998 were included. The percentage reduction in weight or intradialytic weight loss (IDWL%) was defined as the difference between the average of pre- and post-dialysis weights from the last 3 months of 1997 expressed as a percentage of post-dialysis weight. Associations between IDWL% and clinical and demographic variables were estimated using linear regression. The association between mortality risk and IDWL% was estimated using Cox proportional hazards regression.
  
  
  RESULTS
  Younger age, male gender, the presence of diabetes mellitus, decreasing cholesterol, post-dialysis weight and pre-dialysis blood pressure (systolic and pulse pressure) were associated with increased IDWL%. Increasing IDWL% was associated with increasing phosphorus, creatinine, albumin, potassium and urea reduction ratio. Increasing IDWL% was significantly associated with mortality at 1 year [hazard ratio (HR) = 1.07, P = 0.003]. Among patients with diabetes mellitus, increasing IDWL% was associated with a mortality HR of 1.03 (P = 0.02). Among patients without diabetes mellitus, increasing IDWL% was not associated with an increased mortality risk. Increasing IDWL% is associated with a greater mortality risk among patients with creatinine <7.26, which failed to remain significant for patients whose creatinine was >or=7.26 mg/dl. Increasing IDWL% is associated with a greater mortality risk among patients with greater post-dialysis weight, greater body mass index and lower serum sodium measurements.
  
  
  CONCLUSIONS
  This study confirms and extends the findings of the deleterious association between increasing IDWL% and mortality among patients with diabetes mellitus and among subgroups based on serum creatinine and body weight. The putative deleterious effect of dialysis-related volume expansion on mortality must be interpreted in the context of the patient's diabetic and nutritional status.
authors.affiliation: Department of Medicine, Division of Nephrology, Institute for Renal Outcomes Research and Health Policy, Duke University Medical Center, Durham, NC 27705, USA. scze001@mc.duke.edu
authors.forename: Lynda Anne
authors.initials: LA
authors.lastname: Szczech
authors.forename: Donal N
authors.initials: DN
authors.lastname: Reddan
authors.forename: Preston S
authors.initials: PS
authors.lastname: Klassen
authors.forename: Joseph
authors.initials: J
authors.lastname: Coladonato
authors.forename: Benjamin
authors.initials: B
authors.lastname: Chua
authors.forename: Edmund G
authors.initials: EG
authors.lastname: Lowrie
authors.forename: J Michael
authors.initials: JM
authors.lastname: Lazarus
authors.forename: William F
authors.initials: WF
authors.lastname: Owen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003404:Creatinine / Q000097:blood; D005260:Female; D006439:Hemodynamics; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood / Q000401:mortality* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009752:Nutritional Status; D016016:Proportional Hazards Models; D006435:Renal Dialysis; D016019:Survival Analysis; D015430:Weight Gain
chemical_list: D003404:Creatinine