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Kidney Week

Abstract: TH-OR121

Impact of Obesity on Kidney Transplant Outcomes: A Paired-Kidney Analysis

Session Information

Category: Transplantation

  • 1802 Transplantation: Clinical

Authors

  • Chopra, Bhavna, Allegheny General Hospital, Pittsburgh, Pennsylvania, United States
  • McGill, Rita L., University of Chicago, Chicago, Illinois, United States
  • Josephson, Michelle A., University of Chicago, Chicago, Illinois, United States
  • Shah, Pratik B., University of Chicago, Chicago, Illinois, United States
  • Sureshkumar, Kalathil K., Allegheny General Hospital, Pittsburgh, Pennsylvania, United States
Background

The prevalence of obesity is increasing in prospective kidney transplant recipients (KTRs). The impact of recipient obesity on long term outcomes is not clear. We sought to evaluate the associations of recipient body mass index (BMI) with transplant outcomes using a paired-kidney model.

Methods

UNOS data were used to identify all deceased donors between 1/2006 and 12/2016 in which each kidney was used for kidney-alone transplant. Recipient BMIs were classified as: 18-25, >25-30, >30-35, and >35 (reference category). Hazard ratios (HR) for graft failure (GF), death-censored GF (dcGF), and patient death were obtained by marginal survival models adjusted for pairing by donor. Odds ratios (OR) for delayed graft function (DGF) were obtained by conditional logistic regression models. Models were adjusted for recipient and transplant factors.

Results

39,334 paired recipients were evaluated, of whom 4,949 (12.6%) had BMI>35. Median follow up was 43.9 (IQR=22.3-71.8) months, with graft failure in 11.9% and death in 11.0%. Results for adjusted models are shown in table. Compared to patients with BMI>35, patients with BMI 18-25 had lower hazards for both GF and dcGF, but not for death. Patients with BMI >25-30 had lower dcGF. No significant differences seen between BMI >30-35 and BMI>35 for GF, dcGF or death. The odds of DGF were significantly decreased in all BMI groups, compared to BMI>35.

Conclusion

Our paired kidney analysis among a large national transplantation dataset found similar long-term graft and patient outcomes among KTRs with BMI >35 compared to those with BMI 30-35, despite increased DGF. Higher rates of dcGF among all patients with BMI>30 may reflect hyperfiltration, inflammation, subtherapeutic immunosuppression, or increased post-operative complications. Non-inferior patient outcomes among patients with BMI>35 could reflect careful pre-transplant selection among very obese candidates or a survival advantage similar to that of obese dialysis patients.
These data support a more favorable consideration of obese patients for kidney transplantation and suggest that the use of a BMI cut off between 35 and 40, while common, is arbitrary and unfounded.