Obesity complicates kidney transplantation

Jan 14 2013

By Eleanor McDermid, Senior medwireNews Reporter

The risk for delayed graft function (DGF) in patients undergoing kidney transplant rises in line with their body mass index (BMI), say US researchers.

But they stress: "As a whole, our data indicate that while obesity is a significant risk factor for graft failure, the magnitude of the effect is not so large as to preclude patients from transplantation on the basis of BMI alone."

Robert Cannon (University of Louisville, Kentucky) and team analyzed data on 74,983 patients in the United Network for Organ Sharing database. After accounting for confounders, the 20% of patients who were class I obese (BMI 30 to <35) were 1.34-fold more likely than nonobese patients (BMI <30) to have DGF, defined as the need for dialysis within 1 week of transplant.

A further 8% were class II obese (BMI 35 to <40) and 2% were class III obese (BMI ≥40), and these patients had respective 1.68- and 2.68-fold DGF risk increases, relative to nonobese patients.

Patients with class I obesity were no more likely than nonobese patients to experience graft failure (without censoring for death) after adjustment for confounders, but those with class II and III obesity were a significant 24% and 26% more likely to have graft failure, respectively.

"The high degree of statistical significance achieved in this and other studies of its kind, however, is mostly a result of large sample size," comment Cannon et al in the Annals of Surgery. "Whether these differences in survival are clinically significant requires a more subjective assessment."

After adjustment, the 5-year graft survival rates of nonobese and class III obese patients were 81.9% and 78.3%, respectively - just a 3.6% difference. This small difference in graft survival had little impact on overall patient survival, with adjusted 5-year rates of 91.1% and 90.3% for nonobese and class III obese patients, respectively, which was just a 0.8% difference.

"Moreover, considering the high mortality rates for obese patients with renal failure, timely transplantation provides a major survival benefit," say the researchers.

"Thus, we would favor a policy of aggressive risk factor modification and even consideration of bariatric surgery as part of the pretransplant evaluation process for obese patients. Such a strategy strikes an adequate balance between individual patient benefit and the need to maximize the benefits of the scarce organ supply to society as a whole."

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