title: GFR at initiation of dialysis and mortality in CKD: a meta-analysis.
abstract: BACKGROUND
  The proportion of patients with advanced chronic kidney disease (CKD) initiating dialysis therapy at a higher glomerular filtration rate (GFR) has increased during the past decade. Recent data suggest that higher GFR may be associated with increased mortality.
  
  
  METHODS
  A meta-analysis of cohort studies and trials.
  
  
  METHODS
  Patients with advanced CKD.
  
  
  METHODS
  We performed a systematic literature search in MEDLINE, Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, American Society of Nephrology abstracts, and bibliographies of retrieved articles to identify studies reporting on GFR at dialysis therapy initiation and mortality.
  
  
  METHODS
  Estimated or calculated GFR at dialysis therapy initiation.
  
  
  RESULTS
  Pooled adjusted hazard ratio (HR) of continuous GFR for all-cause mortality.
  
  
  RESULTS
  16 cohort studies and 1 randomized controlled trial were identified (n = 1,081,116). By meta-analysis restricted to 15 cohorts (n = 1,079,917), higher GFR at dialysis therapy initiation was associated with a higher pooled adjusted HR for all-cause mortality (1.04; 95% CI, 1.03-1.05; P < 0.001). However, there was significant heterogeneity (I(2) = 97%; P < 0.001). The association persisted among the 9 cohorts that adjusted analytically for nutritional covariates (HR, 1.03; 95% CI, 1.02-1.04; P < 0.001; residual I(2) = 97%). The highest mortality risk was observed in hemodialysis cohorts (HR, 1.05; 95% CI, 1.02-1.08; P < 0.001), whereas there was no association between GFR and mortality in peritoneal dialysis cohorts (HR, 1.04; 95% CI, 0.99-1.08, P = 0.1; residual I(2) = 98%). Finally, higher GFR was associated with a lower mortality risk in cohorts that calculated GFR (HR, 0.80; 95% CI, 0.71-0.91; P = 0.003), contrasting with a higher mortality risk in cohorts that estimated GFR (HR, 1.04; 95% CI, 1.03-1.05; P < 0.001; residual I(2) = 97%).
  
  
  CONCLUSIONS
  Paucity of randomized controlled trials, different methods for determining GFR, and substantial heterogeneity.
  
  
  CONCLUSIONS
  Higher estimated rather than calculated GFR at dialysis therapy initiation is associated with a higher mortality risk in patients with advanced CKD, independent of nutritional status. Although there was substantial heterogeneity of effect size estimates across studies, this observation requires further study.
authors.affiliation: Department of Medicine, Division of Nephrology, Kidney and Dialysis Research Laboratory, St. Elizabeth's Medical Center, Boston, MA 02135, USA.
authors.forename: Paweena
authors.initials: P
authors.lastname: Susantitaphong
authors.forename: Sarah
authors.initials: S
authors.lastname: Altamimi
authors.forename: Motaz
authors.initials: M
authors.lastname: Ashkar
authors.forename: Ethan M
authors.initials: EM
authors.lastname: Balk
authors.forename: Vianda S
authors.initials: VS
authors.lastname: Stel
authors.forename: Seth
authors.initials: S
authors.lastname: Wright
authors.forename: Bertrand L
authors.initials: BL
authors.lastname: Jaber
mesh_terms: D002423:Cause of Death; D015331:Cohort Studies; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D007676:Kidney Failure, Chronic / Q000175:diagnosis / Q000401:mortality / Q000628:therapy; D008297:Male; D010530:Peritoneal Dialysis / Q000379:methods / Q000401:mortality*; D011379:Prognosis; D016032:Randomized Controlled Trials as Topic; D006435:Renal Dialysis / Q000379:methods / Q000401:mortality*; D051436:Renal Insufficiency, Chronic / Q000175:diagnosis / Q000401:mortality* / Q000628:therapy*; D018570:Risk Assessment; D012720:Severity of Illness Index; D016019:Survival Analysis; D014481:United States