title: Association between age and graft failure rates in young kidney transplant recipients.
abstract: BACKGROUND
  Age at transplant and graft failure risk are associated in young kidney transplant recipients. The risk of graft failure may also vary by current age, irrespective of age at transplant. We sought to estimate age-specific graft failure rates in young kidney transplant recipients and to estimate the relative hazards of graft failure at different ages, compared with at the age of 25 to 29 years.
  
  
  METHODS
  We evaluated 90,689 patients recorded in the United States Renal Data System database who received a first transplant when younger than 40 years (1988-2009); 18,310 were younger than 21 years at transplant. Time-dependent Cox models with time-varying covariates were used to estimate the association between age (time-dependent) and death-censored graft failure risk, adjusted for time since transplant and other potential confounders.
  
  
  RESULTS
  There were 31,857 graft failures over a median follow-up of 5.9 years (interquartile range, 2.5-10.5 years; maximum, 21.8 years). Crude age-specific graft failure rates were highest in 19 year olds (6.6 per 100 person-years). Compared with individuals with the same time since transplant observed at 25 to 29 years of age, death-censored graft failure rates were highest in 17 to 24 year olds (hazard ratio, 1.20; [95% confidence interval 1.13, 1.27] for 17-20 year olds and 1.20 [1.13, 1.26] for 21-24 year olds; both P<0.0001) and lowest in 5 to 12 year olds (hazard ratio, 0.60; [0.53, 0.68] for 5-9 year olds and 0.56 [0.49, 0.64] for 10-12 year olds; both P<0.0001).
  
  
  CONCLUSIONS
  Among first kidney transplant recipients younger than 40 years, older adolescents and young adults (17-24 years) have the highest risk of graft failure, irrespective of age at transplant.
authors: Division of Nephrology, Department of Pediatrics, McGill University Faculty of Medicine, Montreal, QC, Canada. beth.foster@muhc.mcgill.ca
authors: Bethany J
authors: BJ
authors: Foster
authors: Mourad
authors: M
authors: Dahhou
authors: Xun
authors: X
authors: Zhang
authors: Robert W
authors: RW
authors: Platt
authors: Susan M
authors: SM
authors: Samuel
authors: James A
authors: JA
authors: Hanley
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000375:Aging / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006084:Graft Rejection / Q000453:epidemiology* / Q000503:physiopathology*; D006085:Graft Survival / Q000502:physiology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D016030:Kidney Transplantation / Q000502:physiology* / Q000706:statistics & numerical data; D008297:Male; D015999:Multivariate Analysis; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D014180:Transplantation / Q000502:physiology*; D014481:United States; D055815:Young Adult