title: Long-term survival rate of kidney graft and associated prognostic factors: a retrospective cohort study, 1994-2011.
abstract: BACKGROUND
  Despite several studies conducted to detect predisposing factors of graft rejection, results are inconsistent and limited. This study was performed to estimate long-term survival rate of kidney transplantation and to detect associated prognostic factors.
  
  
  METHODS
  This retrospective cohort study was conducted in Hamadan Province, in western Iran, enrolling 475 patients who had undergone kidney transplantation from 1994 to 2011. Data were extracted from patients' medical records using a checklist. Chronic nonreversible graft rejection was considered as the event of interest. The duration of time between kidney transplantation and rejection was considered as the survival time. Life table, Kaplan-Meier curve, log-rank test and Cox proportional hazard model were used for data analysis.
  
  
  RESULTS
  Out of 475 transplantations, 55 episodes of rejection occurred. One-, 5-, 10-, 15-, and 18-year survival rates of transplantation were 97.1%, 92.3%, 86.2%, 77.6%, and 60.3%, respectively. The hazard ratio of graft rejection per 1-year increase in recipient age was 0.92 (P=0.001). The hazard ratio of graft rejection was 5.47 for grafts from deceased donors compared to grafts from living donors (P=0.025), and 3.54 (P=0.025) and 47.99 (P=0.001) in patients with episode of acute and hyperacute rejection compared to those without rejection episode, respectively.
  
  
  CONCLUSIONS
  Rejection of kidney transplantation is shaped by several prognostic factors, the most important of which are recipient age, type of donor (living vs. deceased), and episode of post-transplantation acute and hyperacute rejection.
authors.affiliation: Department of Epidemiology and Biostatistics, School of Public Health, Hamadan University of Medical Sciences, Hamadan, Iran.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Saatchi
authors.forename: Jalal
authors.initials: J
authors.lastname: Poorolajal
authors.forename: Mohammad Ali
authors.initials: MA
authors.lastname: Amirzargar
authors.forename: Hossein
authors.initials: H
authors.lastname: Mahjub
authors.forename: Nader
authors.initials: N
authors.lastname: Esmailnasab
mesh_terms: D015331:Cohort Studies; D005260:Female; D006084:Graft Rejection / Q000209:etiology; D006085:Graft Survival; D006801:Humans; D007492:Iran / Q000453:epidemiology; D053208:Kaplan-Meier Estimate; D016030:Kidney Transplantation / Q000009:adverse effects / Q000401:mortality; D008297:Male; D011379:Prognosis; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D015996:Survival Rate; D013997:Time Factors