Renal Function and Remission of Hypertension After Bariatric Surgery: a 5-Year Prospective Cohort Study.

Purpose: This study examines the effect of Roux-en-Y gastric bypass (RYGB) and laparoscopic adjustable gastric banding (LAGB) on renal function for at least 5 years post-operatively in a tertiary referral center for bariatric surgery.
Materials and Methods: This prospective cohort study of patients undergoing RYGB and LAGB measured renal function, blood pressure, and diabetes status pre-operatively and then 1 and 5 years post-operatively. Renal function was assessed using the Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), and Cockcroft-Gault formulae. Hypertension and diabetes were defined by the European Society of Hypertension and European Society of Cardiology joint guidelines and American Diabetes Association guidelines, respectively. A sub-group who had completed 10 years post-operative follow-up was also included.
Results: Estimated glomerular filtration rate (eGFR) increased over 5 years after RYGB (N = 190; 94 ± 2 mL/min/1.73 m ² to 102 ± 22 mL/min/1.73 m ² , p = 0.01) and LAGB (N = 271; 88 ± 1 to 93 ± 22 mL/min/1.73 m ² , p = 0.02). In a sub-group with up to 10 years post-operative date, this trend was maintained. In patients with renal impairment, eGFR improved over 5 years (52 ± 2 to 68 ± 7 mL/min/1.73 m ² , p = 0.01). Remission of hypertension was greater after RYGB than LAGB at 1 year (32 vs. 16 %, p = 0.008) and at 5 years post-operatively (23 vs. 11 %, p = 0.02).
Conclusions: Bariatric surgery stabilizes eGFR post-operatively for at least 5 years. In a sub-group with renal impairment, eGFR is increased in the first post-operative year and this is maintained for up to 5 years. RYGB is an effective procedure in achieving blood pressure control.