title: Full loss of residual renal function causes higher mortality in dialysis patients; findings from a marginal structural model.
abstract: BACKGROUND
  Declining residual renal function, as indicated by the glomerular filtration rate (GFR), is associated with an increased mortality risk in patients with end-stage renal disease (ESRD) on dialysis.
  
  
  METHODS
  We monitored GFR and mortality in 1800 haemodialysis (HD) and peritoneal dialysis (PD) patients in 1996-2006. We used a marginal structural model to estimate the causal effects both of GFR when it was not completely lost and of the subsequent full loss of GFR on mortality, avoiding the drawbacks of standard regression models that include covariates to adjust for confounding. Instead, effect estimates were adjusted for possible baseline and time-varying confounders using inverse probability weighting.
  
  
  RESULTS
  We estimated a hazard ratio (HR) corresponding to the effect of the full loss of GFR on mortality, as compared to not having fully lost GFR, of 1.50 [95% confidence interval (CI) 1.09-2.07]. The HR corresponding to the effect of GFR when GFR is not (yet) fully lost on mortality was 0.97 (95% CI 0.92-1.02) (per mL/min/1.73 m(2)). We found no significant difference in the effect of GFR on mortality between patients starting on PD and HD.
  
  
  CONCLUSIONS
  Preventing or delaying the full loss of GFR can improve survival in dialysis patients. This supports the importance that is given to the effect of treatment options for patients with ESRD on the rate of decline of the residual renal function.
authors.affiliation: Department of Clinical Epidemiology, Biostatistics and Bioinformatics, University of Amsterdam, The Netherlands. w.m.vanderwal-2@umcutrecht.nl
authors.forename: Willem M
authors.initials: WM
authors.lastname: van der Wal
authors.forename: Marlies
authors.initials: M
authors.lastname: Noordzij
authors.forename: Friedo W
authors.initials: FW
authors.lastname: Dekker
authors.forename: Elisabeth W
authors.initials: EW
authors.lastname: Boeschoten
authors.forename: Raymond T
authors.initials: RT
authors.lastname: Krediet
authors.forename: Johanna C
authors.initials: JC
authors.lastname: Korevaar
authors.forename: Ronald B
authors.initials: RB
authors.lastname: Geskus
mesh_terms: D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate; D006801:Humans; D007676:Kidney Failure, Chronic / Q000401:mortality* / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D010530:Peritoneal Dialysis / Q000401:mortality*; D011379:Prognosis; D011446:Prospective Studies; D006435:Renal Dialysis / Q000401:mortality*; D015996:Survival Rate