FRIDAY, Oct. 26, 2018 -- Obese patients in need of a kidney transplant may find themselves denied because of their weight, but a new study says that shouldn't happen in all cases.
Researchers have found that kidneys given to obese patients fared as well as those transplanted into normal-weight patients. In addition, no difference was seen in patient survival, regardless of weight.
Boosting access to transplant "will have a significant impact on quality of life and longevity for these patients, compared to staying on long-term dialysis," said lead researcher Dr. Bhavna Chopra, a nephrologist at Allegheny General Hospital in Pittsburgh.
Many transplant centers have arbitrary cutoffs that prevent obese patients from consideration for a kidney transplant, Chopra said. The bottom line, she said, is that a patient's weight shouldn't be the sole determinant of whether he or she is eligible for a transplant.
Obesity is an issue when it comes to kidney transplants because, Chopra said, the odds of complications during surgery are higher for obese patients, as are possible complications with the organ itself. But the decision should be made on a case-by-case basis, not on weight alone, she added.
For the study, Chopra and her colleagues used information from the United Network for Organ Sharing database from 2006 to 2016 on patients with various levels of body mass index. BMI is a measure of body fat that takes into account a person's weight and height.
A BMI of 18.5 to 24.9 is considered normal, 25 to 29.9 is overweight and above 30 is obese, according to the U.S. Centers for Disease Control and Prevention.
To minimize the effect of different transplanted kidneys as a variable, the researchers paired kidneys from the same deceased donor with recipients who had different BMIs.
They found that although patients with BMIs of 19 to 25 were the ideal for a kidney transplant, there was no difference in overall patient survival across all BMIs.
"Our data support a more favorable consideration of obese patients for kidney transplantation and suggest that the use of a BMI cutoff between 30 and 40 for wait-listing, while common, is arbitrary and unfounded," Chopra said.
Dr. David Klassen, chief medical officer for the United Network for Organ Sharing, said the long-term effects of transplants for obese patients aren't known.
Specifically, it's not clear if overall survival is the same as for normal-weight patients, or whether the transplanted kidney remains functional. Studies have shown that obesity has an effect on the viability of the transplanted organ, he said.
"Still, having an absolute cutoff for obesity probably is not the best way to do it, and a more individualized approach is probably appropriate," Klassen said.
The average wait for a kidney transplant is three to five years, Klassen said. That gives patients time to get into the best shape they can, including losing weight, he noted.
Dr. Sumit Mohan is a nephrologist and associate professor of epidemiology and medicine at Columbia University Medical Center in New York City. He said many transplant centers have increased their BMI cutoff from 35 to 40, which is the difference between obesity and morbid obesity.
Another option for obese patients awaiting a transplant is weight-loss surgery, Mohan said. "There are a number of centers that are debating coupling bariatric surgery and transplant surgery," he said.
"At Columbia, we don't have a BMI cutoff," Mohan said. "If we find that a patient is morbidly obese and that's going to affect their ability to have a transplant, we would then recommend weight loss or bariatric surgery -- we do that quite often."
The results of the study are scheduled for presentation at the annual meeting of the American Society of Nephrology, which runs through Sunday, in San Diego. Research presented at meetings should be viewed as preliminary until it's been published in a peer-reviewed journal.
To learn more about kidney transplants, visit the National Kidney Foundation.
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