Bariatric surgery and progression of chronic kidney disease

BackgroundObesity 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.MethodsWe 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 m²) 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.ResultsA total of 25 patients with stage 3 CKD were included. Their average body mass index at surgery was 49.8 kg/m², the mean GFR was 47.9 mL/min/1.73 m², and the mean serum creatinine was 1.4 mg/dL. The body mass index had decreased to 38.4 kg/m² (paired t test, P < .001) at the end of 6 months and to 34.5 kg/m² (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 m² (P < .001) and to 61.6 mL/min/1.73 m² (P < .001) at 12 months.ConclusionThe 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.