title: The mortality risk of overhydration in haemodialysis patients.
abstract: BACKGROUND
  While cardiovascular events remain the primary form of mortality in haemodialysis (HD) patients, few centres are aware of the impact of the hydration status (HS). The aim of this study was to investigate how the magnitude of the prevailing overhydration influences long-term survival.
  
  
  METHODS
  We measured the hydration status in 269 prevalent HD patients (28% diabetics, dialysis vintage = 41.2 +/- 70 months) in three European centres with a body composition monitor (BCM) that enables quantitative assessment of hydration status and body composition. The survival of these patients was ascertained after a follow-up period of 3.5 years. The cut off threshold for the definition of hyperhydration was set to 15% relative to the extracellular water (ECW), which represents an excess of ECW of approximately 2.5 l. Cox-proportional hazard models were used to compare survival according to the baseline hydration status for a set of demographic data, comorbid conditions and other predictors.
  
  
  RESULTS
  The median hydration state (HS) before the HD treatment (DeltaHSpre) for all patients was 8.6 +/- 8.9%. The unadjusted gross annual mortality of all patients was 8.5%. The hyperhydrated subgroup (n = 58) presented DeltaHSpre = 19.9 +/- 5.3% and a gross mortality of 14.7%. The Cox adjusted hazard ratios (HRs) revealed that age (HRage = 1.05, 1/year; P < 0.001), systolic blood pressure (BPsys) (HRBPsys = 0.986 1/mmHg; P = 0.014), diabetes (HRDia = 2.766; P < 0.001), peripheral vascular disease (PVD) (HRPVD = 1.68; P = 0.045) and relative hydration status (DeltaHSpre) (HRDeltaHSpre = 2.102 P = 0.003) were the only significant predictors of mortality in our patient population.
  
  
  CONCLUSIONS
  The results of our study indicate that the hydration state is an important and independent predictor of mortality in chronic HD patients secondary only to the presence of diabetes. We believe that it is essential to measure the hydration status objectively and quantitatively in order to obtain a more clearly defined assessment of the prognosis of haemodialysis patients.
authors.affiliation: Georg-Haas Dialysezentrum Giessen, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Wizemann
authors.forename: Peter
authors.initials: P
authors.lastname: Wabel
authors.forename: Paul
authors.initials: P
authors.lastname: Chamney
authors.forename: Wojciech
authors.initials: W
authors.lastname: Zaluska
authors.forename: Ulrich
authors.initials: U
authors.lastname: Moissl
authors.forename: Christiane
authors.initials: C
authors.lastname: Rode
authors.forename: Teresa
authors.initials: T
authors.lastname: Malecka-Masalska
authors.forename: Daniele
authors.initials: D
authors.lastname: Marcelli
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001823:Body Composition / Q000502:physiology; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D007674:Kidney Diseases / Q000503:physiopathology / Q000628:therapy*; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D006435:Renal Dialysis; D012189:Retrospective Studies; D012307:Risk Factors; D014883:Water-Electrolyte Imbalance / Q000175:diagnosis / Q000453:epidemiology* / Q000401:mortality*