The impact of obesity on long-term outcomes in liver transplant recipients - Results of the NIDDK Liver Transplant Database

The impact of obesity on outcomes following liver transplantation has been difficult to determine, in part due to the confounding effects of ascites on BMI. We evaluated the impact of pretransplant recipient obesity on outcomes following liver transplantation using the NIDDK Liver Transplantation Database. Pretransplant BMI, corrected for ascites, was categorized as underweight (BMI <18 kg/m²), normal weight (BMI 18-25 kg/m²), overweight (BMI 25.1-30 kg/m²), Class I obese (BMI 30.1-35 kg/m²), Class II obese (BMI 35.1-40 kg/m²) and Class III obese (BMI >40 kg/m²). Primary outcomes were patient and graft survival. Secondary outcomes included days in hospital and days in ICU. Data from 704 adult liver transplant recipients from the NIDDK LTD and a further 609 patients from the Mayo Clinic were analyzed. Early and late patient and graft survival was similar across all BMI categories. Correcting for ascites volume resulted in 11-20% of patients moving into a lower BMI classification. The relative risk for mortality increased by 7% for each liter of ascites removed. We conclude that corrected BMI is not independently predictive of patient or graft survival. Obesity, within the ranges observed in this study, should not be considered to be a contraindication to liver transplantation in the absence of other relative contraindications.