title: Longitudinal Serum Creatinine Levels in Relation to Graft Loss Following Renal Transplantation: Robust Joint Modeling of Longitudinal Measurements and Survival Time Data.
abstract: BACKGROUND
  Chronic kidney disease (CKD) is a major public health problem that may lead to end-stage renal disease (ESRD). Renal transplantation has become the treatment modality of choice for the majority of patients with ESRD. It is therefore necessary to monitor the disease progression of patients who have undergone renal transplantation. In order to monitor the disease progression, the continuous assessment of kidney function over time is considered.
  
  
  OBJECTIVE
  This study aimed to investigate the etiological role of recipient characteristics in serum creatinine changes within the follow-up period and in relation to the graft failure risk, as well as to evaluate whether or not the serum creatinine level represents an indicator of graft failure following renal transplantation.
  
  
  METHODS
  This retrospective cohort study was conducted at the department of nephrology, Baqiyatallah Hospital, Baqiyatallah University of Medical Sciences, between April 2005 and December 2008. The study involved 413 renal transplantation patients. The primary outcomes were the determination of the serum creatinine levels at each attendance and the time to graft failure. Robust joint modeling of the longitudinal measurements (serum creatinine level) and time-to-event data (time to graft failure) were used for the analysis in the presence of outliers in the serum creatinine levels. The data analysis was implemented in WinBUGS 1.4.3.
  
  
  RESULTS
  There was a positive association between the serum creatinine level and graft failure (HR = 5.13, P < 0.001). A one unit increase in the serum creatinine level suggests an increased risk of graft failure of up to 5.13 times. The serum creatinine level significantly decreased over time (95% CI: (-1.58, -1.08)). The recipient's age was negatively associated with the serum creatinine level (95% CI: (-0.02, -0.001)).
  
  
  CONCLUSIONS
  Graft failure is more likely to occur in patients with higher serum creatinine levels.
authors.affiliation: Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, IR Iran.
authors.forename: Shima
authors.initials: S
authors.lastname: Younespour
authors.affiliation: Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, IR Iran.
authors.forename: Abbas
authors.initials: A
authors.lastname: Rahimi Foroushani
authors.affiliation: Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, IR Iran.
authors.forename: Elham
authors.initials: E
authors.lastname: Maraghi
authors.affiliation: Nephrology and Urology Research Center, Baqiyatallah University of Medical Sciences, Tehran, IR Iran.
authors.forename: Zohreh
authors.initials: Z
authors.lastname: Rostami
authors.affiliation: Nephrology and Urology Research Center, Baqiyatallah University of Medical Sciences, Tehran, IR Iran.
authors.forename: Behzad
authors.initials: B
authors.lastname: Einollahi
authors.affiliation: Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, IR Iran.
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Eshraghian
authors.affiliation: Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, IR Iran.
authors.forename: Kazem
authors.initials: K
authors.lastname: Mohammad
keywords: Bayesian Approach; End-Stage Renal Disease (ESRD); Graft Loss; Robust Joint Modeling; Serum Creatinine Level