Effect of body mass index on the survival benefit of liver transplantation.

Obese patients are at higher risk for morbidity and mortality after liver transplantation (LT) than nonobese recipients. However, there are no reports assessing the survival benefit of LT according to recipient body mass index (BMI). A retrospective cohort of liver transplant candidates who were initially wait-listed between September 2001 and December 2004 was identified in the Scientific Registry of Transplant Recipients database. Adjusted Cox regression models were fitted to assess the association between BMI and liver transplant survival benefit (posttransplantation vs. waiting list mortality). During the study period, 25,647 patients were placed on the waiting list. Of these, 4,488 (17%) underwent LT by December 31, 2004. At wait-listing and transplantation, similar proportions were morbidly obese (BMI>or=40; 3.8% vs. 3.4%, respectively) and underweight (BMI<20; 4.5% vs. 4.0%, respectively). Underweight patients experienced a significantly higher covariate-adjusted risk of death on the waiting list (hazard ratio HR]=1.61; P<0.0001) compared to normal weight candidates (BMI 20 to <25), but underweight recipients had a similar risk of posttransplantation death (HR=1.28; P=0.15) compared to recipients of normal weight. In conclusion, compared to patients on the waiting list with a similar BMI, all subgroups of liver transplant recipients demonstrated a significant (P<0.0001) survival benefit, including morbidly obese and underweight recipients. Our results suggest that high or low recipient BMI should not be a contraindication for LT.