Morbid obesity with one or more other serious comorbidities should be a contraindication for liver transplantation

The prevalence of obesity is increasing in the United States and the rest of the world. The World Health Organization reported last year that over a billion people in the world are obese, surpassing 600 million malnourished people. In some ways, this is a reassuring sign that we are combating poverty in the world, but the impact of obesity on long-term morbidity, mortality, and utilization of health resources is similar or higher. The reports from the Centers for Disease Control and the National Health and Nutrition Examination Surveys suggest that 20% of the U.S. population is obese as defined by a body mass index (BMI) 30 kg/ m. Whereas infections are the most common causes of death in the malnourished, degenerative and vascular diseases are the common causes of death in obese people. The Centers for Disease Control estimates that approximately 100 billion dollars are spent every year in the United States on obesity-related type 2 diabetes mellitus and 22 billion on obesity-related osteoarthritis. The United Network for Organ Sharing database from 1988 to 1996 showed that 16.8% of liver transplant recipients had BMI 30 kg/m and of these 5.3% were severely obese (BMI 35 kg/m) and 2.1% were morbidly obese (BMI 40 kg/m). The study reported in this issue of Liver Transplantation by Pelletier et al. shows that the prevalence of obesity has increased significantly in more recent years. Of those who underwent transplantation between 2001 and 2004, 32.5% were obese, and among them, 8.4% were severely obese and 3.2% were morbidly obese. Within a decade, it appears that the prevalence of obesity (BMI 30 kg/m) has increased by 93% among liver transplant recipients, and moreover, there was 58% increase in severe obesity and 52% increase in morbid obesity. This increase is mostly a reflection of the changes in the general population. Fluid overload and inactivity, probably related to the advanced liver disease, may have contributed to the increased prevalence of obesity in this population, but it is difficult to assume that these factors have changed in the past decade. Nevertheless, these data indicate that we need to continue to monitor the outcomes of obese patients on a continuous basis as the epidemiology is rapidly shifting in the wrong direction. The impact of obesity on renal transplantation has been studied more extensively than liver transplantation. An analysis of 51,927 renal transplant recipients showed that extremes of BMI ( 18 and 36) were associated with worse graft and patient survival. In addition, higher BMI was associated with delayed graft function and chronic graft failure. Registry data (from 1987 to 2002) on 6,658 children aged 2 to 17 yr who received renal transplantation showed that BMI 95 percentile (9.7% of the study population) for age was associated with a higher risk of death (relative risk 2.9 for cadaver and 3.7 for living donor) and graft loss (19% vs. 10% for nonobese) due to thrombosis. Obesity has also been described as a negative predictor of morbidity and mortality after combined kidney/pancreas, pancreas alone, lung and heart transplantation. Single center studies on liver transplantation have shown inconsistent results mainly because of the differences in the definition of obesity, sample size, reporting, and