Obesity as predictor of postoperative outcomes in liver transplant candidates: Review of the literature and future perspectives

Background Current American and European guidelines consider a pre-transplant BMI ≥40 kg/m2 as a relative contraindication for liver transplantation but this recommendation is graded as uncertain and requires further research. Moreover, conflicting results are reported on the predictive value of BMI 30–39.9 kg/m2 on post-transplant complication and mortality risk. Aim This study analyzed the data of the literature on the effect of all three BMI classes of obesity on postoperative outcomes in liver transplantation. Materials and methods A PubMed and Cochrane Library search was conducted from inception to October 2015. Results Analysis of the literature demonstrates that discrepancies among studies are mainly either due to limitations of BMI per se, the different BMI cut-offs used to select patients with obesity or reference group and the different outcomes considered. Moreover, the evaluation of visceral adipose tissue and the detrimental effect of muscle mass reduction in presence of obesity are never considered. Conclusions BMI assessment should be used as a preliminary method to evaluate obesity. Subsequently, the assessment of visceral adipose tissue and muscle mass should complete the preoperative evaluation of liver transplant candidates. This innovative approach could represent a new field of research in liver transplantation.