Kidney Transplant

Study: Reconsider BMI Cutoff for Kidney Transplants

A new study presented at the American Society of Nephrology’s Kidney Week 2018 suggested that it may be beneficial to consider patients with obesity more favorably for kidney transplantation.

These findings could have important implications in the future for kidney transplantation, as the prevalence of obesity is on the rise among prospective kidney transplant recipients.

Researchers arrived at their conclusion after analyzing 39,334 paired kidney recipients, of whom 4949 (12.6%) had a body mass index (BMI) of more than 35 kg/m2. Median follow-up lasted 43.9 months.

United Network for Organ Sharing data from deceased kidney donors were collected for kidney-alone transplants occurring between January 2006 to December 2016.

Participants were classified by body mass index (BMI), with categories including:

  • 18 kg/m2 to 25 kg/m2
  • Over 25 kg/m2 to 30 kg/m2
  • Over 30 kg/m2 to 35 kg/m2
  • Over 35 kg/m2 (reference category)


Marginal survival models, adjusted for pairing by donor, were used to calculate hazard ratios for graft failure (GF), death-censored GF (dcGF), and patient death. Conditional logistic regression models were used to determine odds ratios (OR) for delayed graft function (DGF). Each model accounted for recipient and transplant factors.

Over the course of follow-up, GF and death occurred in 11.9% and 11.0%, respectively. Results of the study showed that patients with a BMI of 18 kg/m2 to 25 kg/m2 had lower hazards for GF and dcGF, but not for death. Lower hazards for dcGF were observed in patients with a BMI of more than 25 kg/m2 to 30 kg/m2.

Notably, no significant differences were observed for GF, dcGF, or death for patients with a BMI of more than 30 kg/m2 to 35 kg/m2 vs those with a BMI of more than 35 kg/m2.

The odds of DGF were found to be lower for all BMI groups compared with patients with a BMI of more than 35 kg/m2.

“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 [kg/m2] and 40 [kg/m2], while common, is arbitrary and unfounded,” the researchers concluded.

—Christina Vogt


Chopra B, McGill RL, Josephson MA, Shah PB, Sureshkumar KK. Impact of obesity on kidney transplant outcomes: A paired kidney analysis. Paper presented at: American Society of Nephrology Kidney Week 2018; October 23-28, 2018; San Diego, CA.