title: Waiting time on dialysis as the strongest modifiable risk factor for renal transplant outcomes: a paired donor kidney analysis.
abstract: BACKGROUND
  Waiting time on dialysis has been shown to be associated with worse outcomes after living and cadaveric transplantation. To validate and quantify end-stage renal disease (ESRD) time as an independent risk factor for kidney transplantation, we compared the outcome of paired donor kidneys, destined to patients who had ESRD more than 2 years compared to patients who had ESRD less than 6 months.
  
  
  METHODS
  We analyzed data available from the U.S. Renal Data System database between 1988 and 1998 by Kaplan-Meier estimates and Cox proportional hazards models to quantify the effect of ESRD time on paired cadaveric kidneys and on all cadaveric kidneys compared to living-donated kidneys.
  
  
  RESULTS
  Five- and 10-year unadjusted graft survival rates were significantly worse in paired kidney recipients who had undergone more than 24 months of dialysis (58% and 29%, respectively) compared to paired kidney recipients who had undergone less than 6 months of dialysis (78% and 63%, respectively; P<0.001 each). Ten-year overall adjusted graft survival for cadaveric transplants was 69% for preemptive transplants versus 39% for transplants after 24 months on dialysis. For living transplants, 10-year overall adjusted graft survival was 75% for preemptive transplants versus 49% for transplants after 24 month on dialysis.
  
  
  CONCLUSIONS
  ESRD time is arguably the strongest independent modifiable risk factor for renal transplant outcomes. Part of the advantage of living-donor versus cadaveric-donor transplantation may be explained by waiting time. This effect is dominant enough that a cadaveric renal transplant recipient with an ESRD time less than 6 months has the equivalent graft survival of living donor transplant recipients who wait on dialysis for more than 2 years.
authors.affiliation: Division of Nephrology, Hypertension and Transplantation, University of Florida, Gainesville, USA. meierhu@medicine.ufl.edu.
authors.forename: Herwig-Ulf
authors.initials: HU
authors.lastname: Meier-Kriesche
authors.forename: Bruce
authors.initials: B
authors.lastname: Kaplan
mesh_terms: D000328:Adult; D002102:Cadaver; D005260:Female; D006085:Graft Survival; D006801:Humans; D007676:Kidney Failure, Chronic / Q000628:therapy*; D016030:Kidney Transplantation; D019520:Living Donors; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D006435:Renal Dialysis; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D009927:Tissue and Organ Procurement; D016896:Treatment Outcome