Bariatric Surgery May Increase Risk of Renal Allograft Loss

Possible reasons include malabsorption of immunosuppressive drugs and deposition of oxalate crystals in transplanted kidneys.
Possible reasons include malabsorption of immunosuppressive drugs and deposition of oxalate crystals in transplanted kidneys.

Patients who undergo bariatric surgery prior to kidney transplantation may be more likely to experience graft loss at 1 year than those with a body mass index (BMI) higher than 35 kg/m2 who do not have the surgery, researchers reported at the 2016 American Transplant Congress in Boston.

A team at the Medical University of South Carolina in Charleston led by Titte R. Srinivas, MD, studied 1,167 renal transplant patients, of whom 31 patients underwent bariatric surgery prior to transplantation, 974 had a BMI of 35 kg/m2 or less, and 162 had a BMI above 35 kg/m2. Of the 1,167 patients, 5% experienced 1-year graft loss. The bariatric surgery patients had 3.4 times increased odds of 1-year graft loss compared with patients who had a BMI above 35 kg/m2 who did not undergo the surgery.

Dr Srinivas and colleagues noted that bariatric surgery could lead to decreased absorption of immunosuppressive drugs due to the operation itself or increased oxalate absorption that results in oxalate crystallization in the transplanted kidneys.

Although the increased likelihood of 1-year graft loss did not reach statistical significance, Dr Srinivas said this is because of the relatively small numbers of bariatric surgery patients.  Still, the findings indicate a clinically significant trend that underscores a need for careful patient selection and improved management of immunosuppression, dietary oxalate, and risk factors for oxaluria post-transplant. The study findings confirm the clinical experiences shared by many in the transplant community, he said.

See more coverage from the 2016 American Transplant Congress.

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