CAN BEING OBESE DECREASE SURVIVAL AFTER A KIDNEY TRANSPLANT?

It is estimated that 35 % of adults and 17 % of children are obese in the US. Obesity is related to an increased incidence of a number of serious health issues such as type 2 diabetes, cardiovascular disease, asthma, osteoarthritis, gallbladder disease and certain forms of cancer. Recent data suggests that increasing obesity is an independent risk factor for the development of end stage renal disease (ESRD). Treatment options are limited to dialysis and kidney transplantation after ESRD develops. Each treatment modality has its pros and cons as far the obese patient is concerned.

A study done a few years ago compared survival of obese patients (those with a BMI > 30 kg/m2) on dialysis and after receiving a transplant, which showed a survival benefit of transplantation over dialysis. However, multiple studies have shown increased complications after kidney transplants in obese patients. This has led to increased waiting periods for obese individuals on the transplant list, which itself leads to increasing obesity and more complications. Multiple transplant centers have developed strict protocols and restrictions on how they will mange obese patients on the transplant waiting list. Most centers will not accept patients whose BMI is more than 40 kg/m2 and some even going down to 35 kg/m2 as their upper limit.

Adverse effects due to obesity after a kidney transplant include increased incidence of acute rejection, delayed graft function (defined as the need for dialysis in the first week after a transplant) and eventual failure of the transplant. Increased BMI is associated with a shorter time to graft failure, eventually causing the patient to be put back on dialysis. There is also an increased incidence of wound complications such as wound infections and hernias in obese individuals.

It is estimated that approximately 20 percent of kidney transplant recipients become obese after they receive the transplant. This usually happens in the first two years after the procedure. Most recipients are put on corticosteroids as part of their maintenance immunosuppression to prevent rejection. However, a major side effect of the corticosteroid is weight gain and obesity. Another factor that may contribute to this phenomenon is the hormone leptin. This hormone tapers off after kidney transplantation which contributes to the obesity as well.