How Does Body Weight Effect Kidney Transplant Outcomes?

Decreasing body weight after a kidney transplantation (KT) does not result in improved short-term allograft outcomes or long-term renal function in patients with obesity, according to the results of a recent study.

The researchers conducted a retrospective cohort study that utilized data from the 1990 to 2011 Catalan Renal Registry including 5607 KT recipients.

All participants were categorized into 1 of 4 groups based on their body mass index (BMI) at baseline:

• Underweight (BMI <18.5), which included 3.5% (n = 194) of participants
• Normal weight (BMI ≥18.5–<25), which included 52.8% (n = 2904) of participants
• Pre-obese (BMI ≥25–<30), which included 33.9% (n = 1900) of participants
• Obese (BMI ≥30), which included 10.9% (n = 609) of participants

Primary outcomes of this study included the delayed graft function (DGF), estimated glomerular filtration rate (eGFR), and patient and graft survival. The researchers also calculated the change in patient’s post-transplantation BMI. Patients were followed up until December 2015, death, or they were lost to follow-up.

At the time of transplantation, 10.9% of patients (n = 609) had obesity. A significant association was observed between patients with obesity at baseline and worse short- and long-term graft survival, as well as worse graft function during follow-up. Specifically, in obese patients the rate of DGF was 40.4%, compared with 28.3%) in patients without obesity.

There was no improvement in eGFR, graft, or patient survival based on variations of BMI in obese patients. However, underweight patients with a functioning graft during follow-up had a better eGFR in comparison to the other BMI groups. Patients who underwent a gastrectomy before KT were found to have less DGF and an improved eGFR when compared with a control group.

“In conclusion, in this large retrospective cohort study with long-term follow-up, we show worse renal function and short-term graft survival outcomes in obese patients,” the authors wrote. “The possible long-term benefits of losing weight for graft survival and graft function may be jeopardized by short-term obesity-related complications, particularly DGF. The implication for practice of these findings is that it is necessary to focus on losing weight before KT and not after."

—Leigh Precopio

Reference:

Montero N, Quero M, Arcos E, et al. Effects of body weight variation in obese kidney recipients: a retrospective cohort study. Clin Kidney J. 2020;13(6):1068-1076. doi: 10.1093/ckj/sfz124