Pre-dialysis and post-dialysis hydration status and N-terminal pro-brain natriuretic peptide and survival in haemodialysis patients

Int J Artif Organs. 2016 Aug 19;39(6):282-7. doi: 10.5301/ijao.5000514. Epub 2016 Aug 10.


Purpose: Many dialysis centres have no formal program for assessing and adjusting post-haemodialysis (HD) target weight. Apart from clinical assessment, there are bioimpedance devices and natriuretic peptides that could potentially aid clinical management. We wished to determine whether pre- or post-HD bioimpedance assessment of extracellular water (ECW) or N terminal probrain natriuretic peptide (NT-proBNP) affected patient outcomes.

Methods: Multi-frequency bioimpedance assessments (MFBIA) were made before and after the midweek dialysis session, along with a post-dialysis NT-proBNP measurement.

Results: Data from 362 patients, median age of 63 (50-76) years, 59.7% male, 41.2% Caucasoid, with a median dialysis vintage of 31.4 (13.5-61.7) months were available for review. During a median follow-up of 49.6 (21.9-50.2) months there were 110 (30.4%) deaths. Patients who died had significantly increased ECW, as % over-hydrated both pre-HD 6.6 (5.8-7.6)% vs. survivors 5.1 (4-6.6)%, and post-HD 5.1 (4-6.6)% vs. 0.5 (-1-2.2.0, p<0.001, respectively. They also had higher NT-proBNP 325 (122-791) vs. 102 (48-342) pmol/l, p = 0.002. Using an adjusted Cox model, pre-HD ECW overhydration remained an independent factor associated with mortality (overhydration %: hazard ratio 1.15, 95% limits 1.03-1.28, p = 0.013), with a receiver operator curve (ROC) value of 0.7.

Conclusions: ECW excess is associated with increased mortality for HD patients, with ECW excess pre-dialysis being the strongest association, although these patients also had increased ECW post dialysis. Future trials are required to determine whether achieving euvolaemia as determined by bioimpedance improves patient survival.

MeSH terms

  • Aged
  • Body Composition / physiology
  • Electric Impedance
  • Female
  • Humans
  • Male
  • Middle Aged
  • Natriuretic Peptide, Brain / blood*
  • Peptide Fragments / blood*
  • Proportional Hazards Models
  • Renal Dialysis / mortality*
  • Water-Electrolyte Imbalance / blood
  • Water-Electrolyte Imbalance / mortality*


  • Peptide Fragments
  • pro-brain natriuretic peptide (1-76)
  • Natriuretic Peptide, Brain