Increased recipient body mass index is associated with acute rejection and other adverse outcomes after kidney transplantation.
BACKGROUND
Outcomes of kidney transplant recipients with increased body mass index (BMI) remain controversial. We studied the relationship between BMI and clinically relevant outcomes among kidney transplant recipients at a large center.


METHODS
We performed an observational cohort study of all recipients of kidney transplants at our center from January 1, 2000 to December 31, 2010 to determine if increased BMI at transplantation is associated with adverse outcomes, including delayed graft function and biopsy-proven acute rejection (BPAR). Recipient BMI was categorized as <20, 20 to 24.9 (reference), 25 to 29.9, 30 to 34.9, and ≥35 kg/m. Potential confounders were included in logistic and Cox proportional hazards models.


RESULTS
A total of 1151 patients were studied. Recipient BMI of 30 to 34.9 and ≥35 kg/m were associated with an increased risk of delayed graft function (odds ratio [95% confidence interval [CI], 1.92 [1.16-3.19] and 4.49 [2.24-9.00], respectively). BMI≥35 kg/m was also associated with an increased risk of BPAR (hazard ratio [HR; 95% CI], 2.43 [1.48-3.99]), all-cause graft failure (HR [95% CI], 1.97 [1.09-3.56]), and death-censored graft failure (HR [95% CI], 2.43 [1.07-5.51]). Adjustment for acute rejection as a time-varying covariate significantly attenuated the association with graft failure endpoints. There was no significant relation between BMI and death with graft function.


CONCLUSIONS
Increased BMI at kidney transplantation is a predictor of adverse outcomes, including BPAR. The role of pretransplantation weight reduction in improving graft and patient outcomes requires further study.
1 Division of Nephrology and the Kidney Transplant Program, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada. 2 Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Ontario, Canada. 3 Address correspondence to: S. Joseph Kim, M.D., Ph.D., M.H.S., F.R.C.P.C., Division of Nephrology and the Kidney Transplant Program, Toronto General Hospital, University Health Network, 585 University Avenue, 11C-1183, Toronto, Ontario, Canada M5G 2N2.
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D000208:Acute Disease; D000328:Adult; D000368:Aged; D001706:Biopsy; D015992:Body Mass Index; D051799:Delayed Graft Function / Q000209:etiology; D005260:Female; D006084:Graft Rejection / Q000209:etiology* / Q000473:pathology; D006085:Graft Survival; D006801:Humans; D053208:Kaplan-Meier Estimate; D016030:Kidney Transplantation / Q000009:adverse effects*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009765:Obesity / Q000150:complications* / Q000175:diagnosis; D016017:Odds Ratio; D009864:Ontario; D016016:Proportional Hazards Models; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome