The study authors said they hope their findings improve obese patients' chances of being selected for a kidney transplant.
For the study, Dr. John Gill, of the University of British Columbia in Vancouver, and colleagues analyzed data from more than 208,000 kidney failure patients who received kidney transplants in the United States between 1995 and 2007. The patients were grouped by body-mass index (BMI), which is a measurement of body fat based on height and weight. People with a BMI of 30 or higher are considered obese, and a BMI of 40 or higher is considered extremely obese.
The researchers found that patients with a BMI of 30 to 39 gained a similar survival advantage from kidney transplantation as non-obese patients, which was a 66 percent lower risk of dying during the first year after the transplant.
Patients with a BMI of 40 or higher had a lower survival advantage after a kidney transplant (a 48 percent reduced risk of dying within one year), and it was unclear whether black patients with a BMI of 40 or higher gained any survival advantage.
Among transplant recipients, obese people were more likely than non-obese people to die early, the investigators found. However, the survival differences between obese and non-obese patients were not as great when transplants involved kidneys from live donors, according to the study, which was published in the current issue of the American Journal of Transplantation.
"Our study shows that obese patients derive a survival advantage from transplantation, and obesity should not exclude patients from consideration of transplantation," study author Gill said in a journal news release.
"Also, improved early post-transplant care may help reduce the early risk of death in obese patients, and living donor transplantation may be a useful strategy to mitigate the risks of transplantation in obese transplant candidates," he added.
The National Kidney Foundation has more about kidney transplantation.