title: The Impact of Obesity on Allograft Failure After Kidney Transplantation: A Competing Risks Analysis.
abstract: The impact of pretransplant body mass index (BMI) on long-term allograft outcomes after kidney transplantation remains controversial. The conventional approach of using Kaplan-Meier method to calculate the cumulative risk of death-censored allograft failure may overestimate the risk of failure especially when competing failure risks are present.
  
  
  
  A retrospective cohort of adult first-time kidney transplant recipients was drawn from the Organ Procurement and Transplantation Network database (2001 to 2009). Based on World Health Organization obesity classification, BMI was categorized as: less than 18.5, 18.5 to <25, 25 to < 30, 30 to < 35, 35 to <40 and ≥40 kg/m. Both unadjusted and adjusted risk models were used to assess for risk of allograft failure in the presence of death as a competing event.
  
  
  
  A total of 108 654 recipients were studied. In both unadjusted and adjusted models, increasing BMI level was associated with increased risk of long-term allograft failure. In the adjusted model with BMI 18.5 to less than 25 as the reference, the subhazards ratios (SHRs) for BMI were: less than 18.5: SHR, 0.96; P = 0.41; 25 to less than 30: SHR, 1.05; P = 0.01; 30 to less than 35: SHR, 1.15; P = <0.001; 35 to less than 40: SHR, 1.21; P < 0.001; and greater than 40: SHR, 1.13; P = 0.002.
  
  
  
  Handling of death as a competing event demonstrates a graded, detrimental impact of increasing pretransplant BMI on the risk of graft failure after kidney transplantation in both unadjusted and adjusted models. Compared with previous studies, a lower BMI was not associated with an increased risk of graft loss in a competing risk model.
authors.affiliation: 1 Section of Nephrology, University of Michigan, Ann Arbor, MI. 2 Center for Outcomes Research and Division of Abdominal Transplantation, Saint Louis University, St. Louis, MO.
authors.forename: Abhijit S
authors.initials: AS
authors.lastname: Naik
authors.forename: Ankit
authors.initials: A
authors.lastname: Sakhuja
authors.forename: Diane M
authors.initials: DM
authors.lastname: Cibrik
authors.forename: Akinlolu O
authors.initials: AO
authors.lastname: Ojo
authors.forename: Milagros D
authors.initials: MD
authors.lastname: Samaniego-Picota
authors.forename: Krista L
authors.initials: KL
authors.lastname: Lentine
mesh_terms: D000328:Adult; D064591:Allografts; D015992:Body Mass Index; D005260:Female; D006085:Graft Survival; D006801:Humans; D015994:Incidence; D053208:Kaplan-Meier Estimate; D016030:Kidney Transplantation / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009765:Obesity / Q000175:diagnosis / Q000453:epidemiology* / Q000401:mortality; D011183:Postoperative Complications / Q000175:diagnosis / Q000453:epidemiology* / Q000401:mortality; D016016:Proportional Hazards Models; D012042:Registries; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D009927:Tissue and Organ Procurement; D017211:Treatment Failure; D014481:United States