Obese Kidney Patients Benefit from Transplants

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Nephrology
Obese Kidney Patients Benefit from Transplants
Published: Jul 25, 2013 | Updated: Jul 25, 2013
By Salynn Boyles, Contributing Writer, MedPage Today
Reviewed by Robert Jasmer, MD; Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, BSN, RN, Nurse Planner
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Obese renal failure patients who have BMIs under 40 kg/m2 derive the same overall survival benefit from kidney transplantation as non-obese patients, a study found.
The study findings suggest that obese patients should have the same access to donor kidneys as other patients.
Obese renal failure patients who have a body mass index (BMI) under 40 kg/m2 derive the same overall survival benefit from kidney transplantation as non-obese patients, researchers found.

Standard-criteria donor transplantation was associated with an average 66% reduction in risk of death 1 year after transplant surgery for patients with a BMI under 40, according to John Gill, MD, of the University of British Columbia in Vancouver, and colleagues.

The reduction in risk was 48% for patients with a BMI of 40 or more, compared with continuing on dialysis, they wrote online in the Journal of Transplantation. However, this advantage was uncertain in blacks with BMIs over 40, they noted.

In addition, the death rate among those who had been placed on transplant wait lists was similar for obese and non-obese patients, the investigators found.

The study findings suggest that obese patients should have the same access to donor kidneys as other patients, Gill said.

"We know that obesity is associated with more complications and an overall survival disadvantage following transplant," he told MedPage Today. "But when you look at the relative benefit an obese person gets from transplant compared to staying on dialysis, it is of the same magnitude as what a leaner person would get."

The incidence of obesity is increasing among patients with renal disease, and previous research has found this to be a significant predictor of outcomes.

Obesity appears to convey a survival advantage in kidney failure patients on dialysis, but it is also associated with a higher risk of allograft failure and death following transplant. Given these conflicting outcomes, the survival benefit associated with kidney transplant compared with dialysis in obese patients has been uncertain.

The last major study to address this issue, which included patients transplanted between 1995 and 1999, found a 61% reduction in the risk of death associated with kidney transplant in patients with BMIs of 30 kg/m2 or greater.

Gill said updating the research was important because there are far more renal disease patients who are obese today and these patients often have more comorbidities.

Using data from a national registry of adult end-stage renal disease patients in the U.S., the researchers determined the relative risk of death in transplant recipients grouped by BMI compared with patients on a transplant wait list. The analysis included 208,498 patients. Obesity was defined as a BMI of 30 kg/m2 or more.

In a subanalysis, transplantation was associated with a survival advantage compared to dialysis in most obese patients, including those who were age 50 or over and those who were diabetic.

This advantage did not reach statistical significance for blacks with BMIs of 40 or more, but the researchers noted that point estimates were less than 1 for these patients in all three kidney donor subgroups: standard criteria donors, expanded criteria donors, and living donors.

"It is possible that with a larger sample size, these subgroups could be found to derive a statistically significant but attenuated survival benefit from transplantation," the researchers wrote."Given the observational nature of this study, it is difficult to make definitive recommendations regarding the use of transplantation in black patients with class III obesity."

Among the other findings:

Obesity was associated with an increased risk of early death following transplant, which may largely explain the overall survival disadvantage seen in heavier patients, according to Gill.
All donor sources were associated with a survival advantage over dialysis in most obese patients, but outcomes in live donor kidney recipients were the best. Living donor transplantation was associated with a 66% or more reduction in the risk of death in all weight groups, including the heaviest patients.
"Our analysis suggests that one strategy to minimize the early post-transplant risk of mortality in obese patients is by expanded use of live donor transplantation," the researchers wrote.

One co-author received support from the Kidney Research Scientist Core Education and National Training Program.

The authors reported no conflicts of interest.


Primary source: American Journal of Transplantation
Source reference: Gill JS, et al "The survival benefit of kidney transplantation in obese patients" Am J Tranplant 2013; DOI: 10.1111/ajt.12331.

http://www.medpagetoday.com/Nephrology/ESRD/40679