Bariatric surgery and progression of chronic kidney disease

Background: Obesity is an independent predictor for the development and progression of chronic kidney disease (CKD). The effect of weight reduction on the progression of kidney disease in patients with pre-existing CKD is unclear. Methods: We conducted a retrospective study at a U.S. university hospital of patients with stage 3 CKD (glomerular filtration rate [GFR] 30-59 mL/min/1.73 m(2)) who had undergone bariatric surgery. The renal function of the included patients was recorded for a 2-year period after surgery to analyze the rate of loss or improvement in renal function. The estimated GFR was calculated using the Modification of Diet in Renal Disease 4-variable formula. Patients who developed acute renal failure in the postoperative period were excluded. Results: A total of 25 patients with stage 3 CKD were included. Their average body mass index at surgery was 49.8 kg/m(2), the mean GFR was 47.9 mL/min/1.73 m(2), and the mean serum creatinine was 1.4 mg/dL. The body mass index had decreased to 38.4 kg/m(2) (paired t test, P <.001) at the end of 6 months and to 34.5 kg/m(2) (P <.001) at the end of 12 months. The mean systolic blood pressure had decreased from 133 +/- 13 to 128 +/- 17 mm Hg at the end of 12 months. The mean GFR at 6 months of follow-up had improved to 56.6 mL/min/1.73 m(2) (P <.001) and to 61.6 mL/min/1.73 m(2) (P <.001) at 12 months. Conclusion: The renal function of patients with CKD might improve after bariatric surgery. Larger and long-term studies are warranted to further analyze the effect of bariatric surgery on proteinuria and hard end-points such as the development of end-stage renal disease. (C) 2009 American Society for Metabolic and Bariatric Surgery. All rights reserved.