Bariatric surgery before and after kidney transplantation: long-term weight loss and allograft outcomes.

BACKGROUND: Severe obesity is frequently a barrier to kidney transplantation, and kidney transplant recipients often have significant weight gain following transplantation. OBJECTIVES: The goals of this study were to evaluate the long-term risks and benefits of bariatric surgery before and after kidney transplantation. SETTING: University Hospital, United States. METHODS: We performed a retrospective cohort study of 43 patients who had pretransplantation bariatric surgery and 21 patients who had posttransplantation bariatric surgery from 1994 to 2017 with propensity-score matching to identify matched controls using national registry data. RESULTS: Body mass index at the time of transplantation was similar in patients who underwent bariatric surgery before versus after transplantation (32 versus 34 kg/m2, P = .172). There was no significant difference in body mass index in the 5 years after bariatric surgery among patients who underwent bariatric surgery before versus after kidney transplantation (36 versus 32 kg/m2, P = 0.814). Compared with matched controls, bariatric surgery before (n = 38) and after (n = 18) kidney transplantation was associated with a decreased risk of allograft failure (hazard ratio .31 [95% confidence interval .29-0.33] and .85 [95% confidence interval .85-.86] for pre- and posttransplant, respectively) and mortality (hazard ratio .57 [95% confidence interval .53-.61] and .80 [95% confidence interval .79-.82] for pre- and posttransplant, respectively). CONCLUSIONS: Bariatric surgery before and after kidney transplantation results in similar maintenance of weight loss and improved long-term allograft survival compared with matched controls. Bariatric surgery appears to be a safe and reasonable approach to weight loss both before and after transplantation.