A study by Drexel University researchers indicates the risk of more hospitalizations and death for kidney transplant patients increases for patients asked to lose 10% or more of their weight prior to the transplant.
“Obese adults with advanced kidney disease are often told that they have to lose weight in order to be eligible for a kidney transplant. However, we don’t really have any guidance on the safest way for them to lose the weight,” Meera Harhay, MD, an associate professor in Drexel’s College of Medicine and Dornsife School of Public Health and lead author of the study, said in a press release. “You have to remember, these are patients with organ failure, so losing weight in a healthy way is not necessarily an easy thing to do."
Researchers from Drexel and Johns Hopkins used the Organ Procurement and Transplantation Network database to examine the records of 94,000 deceased donor kidney transplant (DDKT) recipients during a 10-year period. They found patients who lost 10% or more of their body weight prior to a kidney transplant had an 18% greater risk of death after the transplant.
“We found weight loss to signal higher risk across-the-board,” Harhay said. Regardless of whether the patients were underweight or obese before they lost weight (with a BMI above 30 kg/m2 or even 40 kg/m2), the study found significant pre-transplant weight loss was strongly associated with longer stays in the hospital following the procedure, other complications and death.
“There was a non-linear unadjusted association between relative pre-DDKT weight change and transplant hospitalization (length of stay; LOS), with a steep increase in LOS among recipients with > 20% relative pre-DDKT weight loss compared with those with no pre-DDKT weight change,” the authors wrote.
Obesity is common among kidney transplant candidates, the researchers noted. Nearly 35% of patients analyzed in the study were obese when they were listed for transplantation. In many cases, transplant surgeons advise obese patients to lose abdominal belly fat before the transplant surgery because it can complicate the healing process of the surgical incision.
However, Harlay told Healio/Nephrology that finding a measurement tool that could define ideal weight pre-transplant is not well established.
“BMI, and even body weight, are poor proxies for body composition in end-stage kidney disease. A person with a BMI of 35 kg/m2 could be frail with limited mobility, or more muscular and resilient. It would be hard to justify using BMI or body weight alone to deny a person access to kidney transplantation. The whole picture of that person should be considered more than any single number."
The researchers found patients whose weight did not vary as much, losing 5% or less of their total weight, were less likely to have an extended length of stay following the surgery, have a failed transplant or die. This held true even for patients with higher BMIs who would be considered obese or morbidly obese — “a finding that may indicate that even morbidly obese kidney [transplant] recipients with substantial pre-transplant weight loss are at higher risk of death than morbidly obese patients with stable weight,” researchers wrote in the study.
“Without closely monitoring changes in body composition, ‘successful’ weight loss in an obese patient could cause a physician to overlook what would otherwise be a warning sign,” Harhay said. “Our work suggests that we need to be cautious when our patients are losing weight, regardless of BMI and if we know they’re losing muscle mass rather than fat, we can try to intervene.”
Disclosure: This research was supported by grants from the NIH.