Should Kidney Transplantation be Offered to Patients with Body Mass Index >40?: Commentary

Abstract

Obesity continues to rise as a global health concern and significantly affects access to kidney transplantation. Exclusion of high-body mass index (BMI) candidates for transplantation emerged from observational studies in the 1990s and early 2000s, which associated severe obesity with increased perioperative risks, wound dehiscence, surgical site infections, incisional hernias, and graft rejection.1 Additional immunosuppression required to prevent graft rejection increases infection risks, thereby often necessitating reductions in immunosuppression, subsequently elevating the risk of graft loss.1 A recent national survey highlighted that approximately 73% of US transplant programs uphold BMI thresholds of 40 kg/m2 at referral or waitlisting, despite a paucity of evidence to support practice.1Figure 1: Decision algorithm for evaluating and managing kidney transplant candidates with a BMI>40 kg/m 2 . The flow chart integrates multidisciplinary cardiometabolic profiling, comprehensive body composition analysis, surgical feasibility (favoring RAKT), and strategic consideration of bariatric or metabolic interventions when appropriate. BMI, body mass index; RAKT, robotic-assisted kidney transplantation; SG, sleeve gastrectomy.The CON argument for transplantation of high-BMI candidates, presented in this issue by Rita McGill, emphasizes increased risks associated with kidney transplantation in severely obese patients, including surgical complications, delayed graft function, graft failure, and mortality.2 McGill underscores that risks persist despite advances in transplantation methods and are particularly pronounced for patients with class-3 obesity (BMI >40 kg/m2). Additionally, McGill notes ethical considerations related to fair and optimal allocation of scarce donor organs, suggesting that transplantation in this high-risk group compromises both individual patient outcomes and broader organ distribution fairness. Thus, the CON perspective advocates caution and prioritization of resources toward patients likely to derive maximum benefit with minimal risk. Conversely, the PRO argument, presented by Amanda Vinson in this issue, emphasizes the substantial survival advantage kidney transplantation provides to patients with BMI >40 kg/m2 compared with dialysis.3 Vinson highlights significant limitations of BMI for risk assessment, noting insufficient differentiation between muscle, bone, and fat mass nor accounting for body fat distribution, crucial for accurately assessing metabolic risk. Moreover, Vinson stresses that BMI thresholds exacerbate health inequities, arguing for individualized assessments rather than uniform BMI-based eligibility cutoffs. Thus, from the PRO perspective, restricting transplantation based on BMI thresholds is not only clinically counterproductive but also ethically questionable. Current evidence differentiates between modifiable and nonmodifiable risk factors.2 For instance, obese patients undergoing dialysis frequently demonstrate paradoxically better survival rates compared with their leaner counterparts because of enhanced metabolic reserves, an observation termed reverse epidemiology.4 Additionally, the association of BMI with post-kidney transplant outcomes is significantly modified by factors including patient age, race/ethnicity, sex, and primary diagnosis.5 Although subcutaneous fat contributes to higher incidence of wound infections because of poor vascularization, surgical variables such as incision size, meticulous tissue handling, and ischemia time remain modifiable and controllable factors. Importantly, significant advances in minimally invasive surgical techniques, particularly robotic-assisted kidney transplantation (RAKT), have altered this risk-benefit evaluation. Initially introduced for donor nephrectomies, robotic techniques have expanded to recipient procedures, significantly reducing perioperative morbidity. Tzvetanov et al. demonstrated that among 239 RAKT recipients with median BMI=4