Purpose: The relationship between the body mass index (BMI) of kidney transplant recipients and outcomes after kidney transplantation (KT) is not fully understood and remains controversial. We studied the influence of BMI on clinically relevant outcomes in kidney transplant recipients.
Methods: In this retrospective single-centre study, all patients who underwent kidney transplantation at our institution between January 2007 and December 2012 were included. Demographic data and BMI were correlated with the clinical course of the disease, rejection rates, delayed graft function rates, and graft and patient survival.
Results: During the study period, 384 single KTs (130 women and 254 men) were performed. Seventeen percent of the transplants were transplanted within the Eurotransplant Senior Programme (ESP). Most of the transplants were performed using organs that were obtained from donors after brain death (DBD), and living donor kidney transplants were performed in 22.4% of all transplants. The median BMI of the recipients was 25.9 kg/m2. Additionally, 13.5% of the recipients had a BMI of 30-34.9 kg/m2 and 3.9% had a BMI >35 kg/m2. A BMI >30 kg/m2 was significantly associated with primary non-function of the kidney (p = 0.047), delayed graft function (p = 0.008), and a higher rate of loss of graft function (p = 0.015). The glomerular filtration rate 12 months after KT was significantly lower in recipients with a BMI >30 kg/m2. Multivariate analysis revealed that recipient BMI, among other factors, was an independent risk factor for delayed graft function and graft survival. Patients with a BMI >30 kg/m2 had an almost four times higher risk for surgical site infection than did recipients with a lower BMI.
Conclusions: Increased BMI at kidney transplantation is a predictor of adverse outcomes, including delayed graft function. These findings demonstrate the importance of the careful selection of patients and pre-transplant weight reduction, although the role of weight reduction for improving graft function is not clear.
Keywords: Body mass index; Graft survival; Kidney function; Kidney transplantation.