title: Residual renal function at the start of dialysis and clinical outcomes.
abstract: BACKGROUND
  This study evaluates the association between estimated GFR (eGFR) at the start of dialysis and mortality within Europe.
  
  
  METHODS
  Renal registries participating in the ERA-EDTA Registry were asked to provide data on serum creatinine recorded 0-4 weeks before the start of dialysis in incident dialysis patients in 1999 and 2003. Within this cohort study, data were available in 11 472 patients from nine national or regional European renal registries. Cox regression analyses were performed to examine the association between GFR estimated by the four-variable MDRD equation (eGFR) and all-cause mortality, using a follow-up through 31 December 2005.
  
  
  RESULTS
  In the 2003 data, the mean eGFR was 8.6 ml/min/1.73 m(2). The unadjusted survival analyses showed that an increase in eGFR of 1 ml/min/1.73 m(2) was associated with a higher mortality risk (HR = 1.03; 95% CI: 1.03-1.04) that remained similar after adjustment for age, gender, primary renal disease, treatment modality, country and comorbidity. The findings were consistent across gender, treatment modalities, geographical regions and time periods (2003 versus 1999), but the association between a higher eGFR at the start of dialysis and mortality was the strongest in the youngest age groups and in patients with glomerulonephritis. Analyses at centre level showed that a 10% increase in the percentage of patients starting dialysis at high eGFR levels (>or=10.5 ml/min) was associated with a 22% higher mortality risk (HR = 1.22; 95% CI: 1.18-1.26).
  
  
  CONCLUSIONS
  This European study showed that a higher eGFR at the start of dialysis was associated with a higher mortality risk. However, an answer to the question when to start dialysis needs to come from randomized controlled trials.
authors.affiliation: Department of Medical Informatics, ERA-EDTA Registry, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands. v.s.stel@amc.uva.nl
authors.forename: Vianda S
authors.initials: VS
authors.lastname: Stel
authors.forename: Friedo W
authors.initials: FW
authors.lastname: Dekker
authors.forename: David
authors.initials: D
authors.lastname: Ansell
authors.forename: Hans
authors.initials: H
authors.lastname: Augustijn
authors.forename: Francesco G
authors.initials: FG
authors.lastname: Casino
authors.forename: Frederic
authors.initials: F
authors.lastname: Collart
authors.forename: Patrik
authors.initials: P
authors.lastname: Finne
authors.forename: George A
authors.initials: GA
authors.lastname: Ioannidis
authors.forename: Mario
authors.initials: M
authors.lastname: Salomone
authors.forename: Jamie P
authors.initials: JP
authors.lastname: Traynor
authors.forename: Oscar
authors.initials: O
authors.lastname: Zurriaga
authors.forename: Enrico
authors.initials: E
authors.lastname: Verrina
authors.forename: Kitty J
authors.initials: KJ
authors.lastname: Jager
mesh_terms: D000328:Adult; D000368:Aged; D005060:Europe; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007668:Kidney / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis / Q000401:mortality*; D012189:Retrospective Studies; D055815:Young Adult