The global epidemic of obesity is reflected in the end-stage renal disease (ESRD) population where the proportion of recipients with a body mass index (BMI) of ≥30 kg/m2 is doubled every 15 yr [1], [2]. According to the 2022 US epidemiological data [3], 16.5% of chronic kidney disease (CKD) patients were obese, and obesity increases the risk of progression to ESRD [4].

Kidney transplantation (KT) is the best renal replacement therapy and provides better quality of life than long-term dialysis [5], [6]. Unfortunately, obesity may be an obstacle to transplantation access, due to a higher risk of surgical and medical complications, including wound healing, delayed graft function (DGF), hospital readmissions, or new-onset diabetes [7], [8]. Obese recipients show shorter transplant survival than nonobese recipients after transplantation from a deceased donor [9]; together with the medical and surgical challenge, in the context of organ shortage, this may create some unconscious bias from transplant teams and discriminate obese patients by reducing their access to transplantation [10]. Therefore, KT in obese patients is still discussed controversially [11]. Obesity may be detrimental to recipient survival via its association with these early postoperative complications as well as with other medical conditions such as type 2 diabetes mellitus, cardiovascular disease, and chronic respiratory disorders [12], [13], [14]. Moreover, KT surgery presents several challenges in obese patients, related to the depth of the iliac vessels. However, compared with remaining on a waiting list, KT in obese recipients improves long-term survival [15] and enhances quality of life [16], even though morbid obesity is strongly associated with reduced long-term patient and graft survival [17], [18]. Several meta-analyses investigated KT in obese recipients [19], [20], [21], [22], with controversial outcomes, especially concerning patient and graft survival. These previous analyses, which are now >5 yr old, often included studies with abstracts only and lacked the incorporation of sensitivity analyses.

The aim of this study was to perform a systematic review and meta-analysis to appraise all available evidence about the outcomes of KT in obese (BMI ≥30 kg/m2) versus nonobese (BMI <30 kg/m2) patients.