Obese patients wait longer for kidney transplants, research suggests

December 19, 2007

New research from Johns Hopkins specialists suggests that obese kidney disease patients face not only the usual long odds of a tissue match and organ rejection, but also are significantly less likely than normal-weight people to receive a kidney transplant at all.

The Johns Hopkins study results, to be published online this Wednesday in the Journal of the American Society of Nephrology, reveal that morbidly obese patients (those who on average weigh 100 pounds more than their ideal weight) are on the transplant waiting list for a median of five years - two years more than the median wait time for a patient of normal weight.

Because patients tend to get sicker the longer they wait on dialysis, obese patients are 44 percent less likely than normal-weight patients to ever receive a kidney transplant, the researchers report. Each year, 8 percent of the patients on the list die waiting for a kidney.

Johns Hopkins transplant surgeon Dorry Segev, M.D., who led the study, suggests that obese patients might be turned down, sometimes multiple times, because of the added cost and poorer outcome associated with transplants in overweight patients.

"Being overweight should not be a disqualifying and discriminating factor against these patients," Segev says.

He adds that at Johns Hopkins, the rate at which overweight, severely obese, and morbidly obese patients are listed and receive transplants is much higher than the national average. As a result, the waiting times for obese patients are not significantly different.

"Patients understandably believe that being placed on the transplant waiting list is an implicit promise of fair, unbiased treatment under a transparent allocation scheme," Segev says. "Unfortunately, the system that has been established nationally may not be living up to that promise."

The study's findings may be explained, he says, by economic pressures as well as medical ones. He notes that Medicare - the principal insurer for kidney transplants - pays a set amount for the operation regardless of a patient's overall health, difficulty of the operation, length of stay, postoperative care and complications, all of which may increase substantially with obese patients. Transplant centers, therefore, may be under pressure to avoid operating on these individuals.

In addition, Segev says, centers with lower surgical survival rates overall risk losing Medicare funding.

The researchers analyzed data from 132,353 men and women with kidney disease who were on the United Network for Organ Sharing (UNOS) deceased donor kidney transplantation list from 1995 to 2006 in the United States.

Patients' weight was rated using the body mass index (BMI) scale - weight in kilograms divided by height in meters squared. A normal BMI is 18.5. Overweight is 25 (25 to 30), obese is 30 to 35 severely obese is 35 to 40 and morbidly obese is 40 to 60.

Of the group analyzed, 48,349 were of normal weight, 45,411 were overweight, 25,509 were obese, 9,479 were severely obese and 3,605 were morbidly obese.

After adjusting for additional health factors that might affect a person's eligibility for transplantation (such as blood type, age, type of kidney disease, diabetes and heart disease), the researchers found that the likelihood of receiving a transplant, when compared to patients with a normal weight, decreases by 4 percent for overweight patients, 7 percent for obese patients, 28 percent for severely obese patients and 44 percent for morbidly obese patients.

Segev says the number of overweight patients joining the UNOS waiting list has gone up markedly in the last decade as the rate of obesity has grown in the U.S. population. From 1995 to 2005, the number of severely obese patients added to the list increased by 310 percent, and the number of morbidly obese patients added to the list increased by 247 percent. In contrast, the number of people of normal weight added to the list increased by only 33 percent.

"The transplant community needs to develop appropriate guidelines stipulating which patients are appropriate for transplantation and to do our best to treat them equally," says Segev. "Similarly, both outcomes evaluation and reimbursement need to reflect the varying difficulty of care for these patients in order to remove the disincentives of taking on challenging cases."

A study by Johns Hopkins surgeon Anne Lidor, M.D., is currently examining whether overweight transplants patients should be recommended for gastric bypass surgery at the time they're first listed.

"This would improve survival while the patient is waiting for a kidney and also improve survival after receiving the kidney, which should eliminate any potential bias for receiving a kidney in a timely fashion," says Segev.
Additional Johns Hopkins researchers who contributed to this paper include Robert A. Montgomery, M.D., Ph.D.; Christopher E. Simpkins, M.D.; Jayme E. Locke, M.D.; and Daniel S. Warren, Ph.D., of the Department of Surgery; and Richard E. Thompson, Ph.D., of the Bloomberg School of Public Health.

Johns Hopkins Medicine

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