title: Interdialytic Weight Gain: Trends, Predictors, and Associated Outcomes in the International Dialysis Outcomes and Practice Patterns Study (DOPPS).
abstract: BACKGROUND
  High interdialytic weight gain (IDWG) is associated with adverse outcomes in hemodialysis (HD) patients. We identified temporal and regional trends in IDWG, predictors of IDWG, and associations of IDWG with clinical outcomes.
  
  
  METHODS
  Analysis 1: sequential cross-sections to identify facility- and patient-level predictors of IDWG and their temporal trends. Analysis 2: prospective cohort study to assess associations between IDWG and mortality and hospitalization risk.
  
  
  METHODS
  21,919 participants on HD therapy for 1 year or longer in the Dialysis Outcomes and Practice Patterns Study (DOPPS) phases 2 to 5 (2002-2014).
  
  
  METHODS
  Analysis 1: study phase, patient demographics and comorbid conditions, HD facility practices. Analysis 2: relative IDWG, expressed as percentage of post-HD weight (<0%, 0%-0.99%, 1%-2.49%, 2.5%-3.99% [reference], 4%-5.69%, and ≥5.7%).
  
  
  RESULTS
  Analysis 1: relative IDWG as a continuous variable using linear mixed models; analysis 2: mortality; all-cause and cause-specific hospitalization using Cox regression, adjusting for potential confounders.
  
  
  RESULTS
  From phase 2 to 5, IDWG declined in the United States (-0.29kg; -0.5% of post-HD weight), Canada (-0.25kg; -0.8%), and Europe (-0.22kg; -0.5%), with more modest declines in Japan and Australia/New Zealand. Among modifiable factors associated with IDWG, the most notable was facility mean dialysate sodium concentration: every 1-mEq/L greater dialysate sodium concentration was associated with 0.13 (95% CI, 0.11-0.16) greater relative IDWG. Compared to relative IDWG of 2.5% to 3.99%, there was elevated risk for mortality with relative IDWG≥5.7% (adjusted HR, 1.23; 95% CI, 1.08-1.40) and elevated risk for fluid-overload hospitalization with relative IDWG≥4% (HRs of 1.28 [95% CI, 1.09-1.49] and 1.64 [95% CI, 1.27-2.13] for relative IDWGs of 4%-5.69% and ≥5.7%, respectively).
  
  
  CONCLUSIONS
  Possible residual confounding. No dietary salt intake data.
  
  
  CONCLUSIONS
  Reductions in IDWG during the past decade were partially explained by reductions in dialysate sodium concentration. Focusing quality improvement strategies on reducing occurrences of high IDWG may improve outcomes in HD patients.
authors.affiliation: Arbor Research Collaborative for Health, Ann Arbor, MI; Department of Medicine, University of British Columbia, Vancouver, BC, Canada. Electronic address: michellemywong@gmail.com.
authors.forename: Michelle M Y
authors.initials: MM
authors.lastname: Wong
authors.affiliation: Arbor Research Collaborative for Health, Ann Arbor, MI.
authors.forename: Keith P
authors.initials: KP
authors.lastname: McCullough
authors.affiliation: Arbor Research Collaborative for Health, Ann Arbor, MI.
authors.forename: Brian A
authors.initials: BA
authors.lastname: Bieber
authors.affiliation: Universität Heidelberg, Heidelberg, Germany.
authors.forename: Juergen
authors.initials: J
authors.lastname: Bommer
authors.affiliation: Department of Internal Medicine III-Nephrology, Medical University of Vienna, Vienna, Austria.
authors.forename: Manfred
authors.initials: M
authors.lastname: Hecking
authors.affiliation: Renal Research Institute, New York, NY.
authors.forename: Nathan W
authors.initials: NW
authors.lastname: Levin
authors.affiliation: Department of Medicine, Emory University, Atlanta, GA; Department of Epidemiology, Emory University, Atlanta, GA.
authors.forename: William M
authors.initials: WM
authors.lastname: McClellan
authors.affiliation: Arbor Research Collaborative for Health, Ann Arbor, MI.
authors.forename: Ronald L
authors.initials: RL
authors.lastname: Pisoni
authors.affiliation: Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI; Kidney Epidemiology and Cost Center, University of Michigan, Ann Arbor, MI.
authors.forename: Rajiv
authors.initials: R
authors.lastname: Saran
authors.affiliation: Arbor Research Collaborative for Health, Ann Arbor, MI.
authors.forename: Francesca
authors.initials: F
authors.lastname: Tentori
authors.affiliation: Department of Nephrology, Faculty of Medicine, Oita University Hospital, Oita, Japan; Department of Internal Medicine II, Faculty of Medicine, Oita University Hospital, Oita, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Tomo
authors.affiliation: Arbor Research Collaborative for Health, Ann Arbor, MI; Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI.
authors.forename: Friedrich K
authors.initials: FK
authors.lastname: Port
authors.affiliation: Arbor Research Collaborative for Health, Ann Arbor, MI; Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI.
authors.forename: Bruce M
authors.initials: BM
authors.lastname: Robinson
mesh_terms: D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D007676:Kidney Failure, Chronic / Q000401:mortality / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D010818:Practice Patterns, Physicians'; D011446:Prospective Studies; D006435:Renal Dialysis; D013997:Time Factors; D015430:Weight Gain
keywords: Interdialytic weight gain (IDWG); dialysate sodium; dialysis facility practice patterns; end-stage renal disease (ESRD); fluid overload; hemodialysis; hospitalizations; modifiable risk factor; mortality; sodium gradient