Too fat, too thin

One of the dreaded complications of chronic hepatitis B and C viral infection is the development of liver cirrhosis. As the cirrhosis progress, the hardened liver would no longer be able to sustain life, thus, precipitating the need for a liver transplant. Will the fact that one is under-weight or over-weight at the time of liver transplantation influence patient outcome?

Researchers at the University of Washington examined the United Network for Organ Sharing (UNOS) database from 1987 to 2007 in order to determine the morbidity and mortality of patients undergoing liver transplantation at the extremes of the body mass index (BMI). The 73,538 recipients were stratified into 6 BMI categories: underweight (< 18.5 kg/m²), normal weight (18.5 - < 25 kg/m²), overweight (25 - < 30 kg/m²), obese (30 - < 35 kg/m²), severely obese (35 - < 40 kg/m²) and very severely obese (≥ 40 kg/m²). There were 1827 patients in the underweight group, 1447 patients in the very severely obese group and 68,172 patients in the other groups, which became the control (Liver Transpl 2009; 15: 968 – 977). Groups at the extreme ends of BMI (<18.5 and ≥ 40) were compared to control. The analysis showed that underweight patients are more likely to die from haemorrhagic complications and cerebrovascular accidents. The very severely obese patients were more likely to die from infectious complications and cancers. Thus, underweight and very severe obesity were significant predictors of death in those who had liver transplantation.

Is this poorer outcome also evident in other organ transplantation, such as kidney transplantation? Not much information is available for under-weight recipients. What about over-weight recipients? A study from University Hospital of Wales analysed the outcomes of 114 obese kidney recipients, allocated into Group A (BMI 30 – 34.9, moderate obesity) and Group B (BMI ≥ 35, morbid obesity). The 1 year and 5 year patient survival rates in Group A were 98.9% and 95.6% respectively, compared to 87.5% and 79.2% respectively in Group B patients. The degree of obesity also influenced kidney graft survival. The 5 year graft survival rate in Group A was 94.5% compared to only 63% in Group B (Transplant Proc 2008; 40: 3408 – 3412). Morbidly obese kidney recipients have a significantly poorer outcome.

It is easy to become over-weight. It is more difficult to become under-weight. Obesity has become a global health issue and will become a major health problem in the 21^st century. You have a big say in whether you become too fat or just right. Choose wisely!