Are some patients too heavy for a new kidney?

January 14, 2013, Saint Louis University

In a research review article published in the American Journal of Nephrology, Saint Louis University investigators examined data from multiple studies to better understand how obesity, an epidemic in the U.S., impacts kidney transplant patients. The authors report that, even as some connections between weight and health outcomes are unknown or contradictory, there is evidence that obese kidney transplant patients don't do as well after surgery, experiencing more adverse outcomes, including wound infections, delayed graft function, graft failure, cardiac disease and increased costs.

Led by Krista Lentine, M.D., associate professor of internal medicine in nephrology and Betsy Tuttle-Newhall, M.D., director of abdominal transplant at SLU, the authors examined multiple studies and concluded that the health outcomes of with higher body mass indices (BMI) are not as good. In addition, they found several areas where more study is needed in order to make clear and consistent recommendations about kidney transplants for heavier patients.

"Lifestyle alterations that seem reasonable to improve health outcomes should be encouraged," Tuttle Newhall said. "Just as we require patients with to stop drinking prior to transplant, it is reasonable to ask kidney transplant candidates to lose excess body fat and attempt to increase lean muscle mass by becoming more physically active and modifying their diet."

Lentine, who also holds an appointment in the Saint Louis University Center for Outcomes Research (SLUCOR), says the study points the way for future research to fill in gaps in our knowledge about how weight affects kidney transplant patients.

"Current guidelines from the American Society of Transplantation recommend a supervised weight loss regimen including a , behavioral therapy, and a physical activity plan to achieve a (BMI) of less than 30 prior to ," Lentine said. "But, these guidelines also note that we don't have enough data to determine if some obese patients aren't appropriate candidates to receive kidney transplants at all.

"For this reason, current acceptable BMI limits for kidney vary across transplant centers."

The authors say future investigations should seek to determine the upper BMI limit at which point kidney transplantation should not be recommended for obese patients. In addition researchers note the limitations of BMI alone as a measure of body fat, and suggest further research using more refined measures.

While obese transplant recipients appear to have worse outcomes compared to normal weight recipients, the authors also note that many obese dialysis patients have better long-term survival after a transplant compared with remaining on dialysis.

In addition, doctors are aware of an "obesity paradox" when it comes to dialysis patients. Kidney patients on dialysis appear to benefit from extra fat, living longer than normal weight patients. Researchers do not know how extra weight provides a protective benefit, but believe that this relative benefit does not occur in transplant scenarios.

The benefit of losing weight prior to a kidney transplant also is unproven. More study is needed to determine whether intentional weight loss before surgery, including diet, exercise and bariatric surgery, does, in fact, improve outcomes. The current understanding is murky because the available data does not distinguish between weight lost deliberately, through healthy diet, exercise or bariatric surgery, and spontaneous weight loss due to illness.

Bariatric surgery, in particular, needs to be studied further. Dialysis patients face bigger risks from surgery and it is unknown if it serves to offset the apparent risks of obesity when performed prior to a kidney transplant.

"This review showed us where there are gaps in the existing research and where current data is too light to be able to draw solid conclusions," said Lentine. "These gaps are what 'outcomes research' is designed to remedy.

"We've figured out some key questions to ask so that we can help our patients have successful transplants and healthy lives."

BOTTOM LINE

  • Obesity appears to affect in a negative way, leading to complications during their recovery.
  • Kidney patients should know that their weight may affect the success of a transplant and should work with their doctor to manage it in a healthy way.
  • Doctors need future studies to examine the upper BMI limit at which kidney transplantation should not be recommended for obese patients, to refine ways of measuring obesity, and to define the benefits of losing prior to a .

Explore further: Race, insurance status related to likelihood of being assessed for kidney transplantation

Related Stories

Race, insurance status related to likelihood of being assessed for kidney transplantation

July 26, 2012
Young black patients and patients without private health insurance are less likely to be assessed for a kidney transplant when they start dialysis, according to a study appearing in an upcoming issue of the Clinical Journal ...

First simultaneous robotic kidney transplant, sleeve gastrectomy performed

August 31, 2012
Surgeons at the University of Illinois Hospital & Health Sciences System are developing new treatment options for obese kidney patients.

Weight-loss surgery seems safe for kidney disease patients

March 1, 2012
(HealthDay) -- Obese chronic kidney disease patients who undergo surgery to achieve weight loss do not face a particularly dangerous rate of complications as a result, a new study suggests.

Recommended for you

Study shows how MERS coronavirus evolves to infect different species

August 14, 2018
In the past 15 years, two outbreaks of severe respiratory disease were caused by coronaviruses transmitted from animals to humans. In 2003, SARS-CoV (severe acute respiratory syndrome coronavirus) spread from civets to infect ...

Inching closer to a soft spot in isoniazid-resistant tuberculosis

August 14, 2018
Antibiotic-resistant tuberculosis is a public health threat. TB and other bacteria become resistant to antibiotics by evolving genetic changes over time, which they can do quite quickly because bacterial lifecycles are short. ...

How long is an Ebola survivor contagious? One case is causing scientists to rethink the answer.

August 14, 2018
Surviving Ebola isn't like getting over the flu.

Why do women get more migraines?

August 14, 2018
Research published today reveals a potential mechanism for migraine causation which could explain why women get more migraines than men. The study, in Frontiers in Molecular Biosciences, suggests that sex hormones affect ...

Link between common 'harmless' virus and cardiovascular damage

August 13, 2018
Researchers from Brighton and Sussex Medical School (BSMS) have found an unexpectedly close link between a herpes virus and the occurrence of immune cells damaging cardiovascular tissue.

Rotavirus vaccine cuts infant diarrhoea deaths by a third in Malawi

August 11, 2018
A major new study has shown that rotavirus vaccination reduced infant diarrhoea deaths by 34% in rural Malawi, a region with high levels of child deaths.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.