Improvement in Estimated Glomerular Filtration Rate After Bariatric Surgery: A New Application for Bariatric Surgery On the Horizon?

Michael L Hibbard, MD, Andrea R Giovanelli, Megan Palsa, PAC, Teresa Kim, MD, Gregory Broderick-villa, MD, Ajay Upadhyay, MD. First Surgical Consultants, Alta Bates Summit Medical Center, Oakland, California, U.S.A.

Introduction: Bariatric surgery has been shown to improve multiple conditions that are known risk factors for renal disease. Despite this, there remains a paucity of evidence to support the benefits of bariatric surgery on renal function. We hypothesized that a demonstrable improvement in estimated glomerular filtration rate would be seen in our bariatric surgery patients.
Methods and Procedures: A retrospective review of prospectively collected data of 186 patients who underwent minimally invasive bariatric surgery as treatment for morbid obesity from Jan 2009 through Dec 2009. Demographic and laboratory data was collected and used to calculate estimated glomerular filtration rate (eGFR) using the 6 variable modification of diet in renal disease formula. Significance was then determined using the paired t-test.
Results: A laparoscopic adjustable band system was used in 48 patients, 7 patients underwent laparoscopic sleeve gastrectomy, and 131 underwent laparoscopic gastric bypass with roux-en-y reconstruction. The mean eGFR showed significant improvement from 86.89 ml/min/1.73m2 pre-operatively to 98.03 ml/min/1.73m2 by 6 month follow-up (p=0.01) with a mean percent excess body weight (%EBW) loss of 42.98 pounds. At 1 year follow-up, the improvement in mean eGFR remained significant at 95.87 ml/min/1.73m2 (p=0.001) with %EBW loss of 51.76.
Conclusion: Our data suggest a clear improvement in renal function as calculated by eGFR. Though significance in eGFR was apparent by 6 months and held through 1 year follow-up, longer follow-up and prospective analysis is needed. Whether improvement in renal function is due to direct effects of weight loss or by the indirect effects of modification of risk factors has yet to be determined. If progression of renal dysfunction can be slowed or reversed with weight loss surgery, the extensive financial and lifestyle burden of dialysis may be delayed or avoided.
 

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