K. Chawla1, A. Vij1, S. Ajmeri1, A. L. Rodriguez1, G. Gilot1, F. De Souza3, G. Ortega3, C. O. Callender2, T. Fullum2 1Howard University,College Of Medicine,Washington, DC, USA 2Howard University College Of Medicine,Division Of Minimally Invasive And Bariatric Surgery, Department Of Surgery,Washington, DC, USA 3Howard University College Of Medicine,Outcomes Research Center, Department Of Surgery,Washington, DC, USA
Introduction: Obesity is associated with a number of comorbidities including chronic kidney disease (CKD). Bariatric surgery results in significant weight loss and post-operative improvements in estimated glomerular filtration rate (eGFR). There is a paucity of data on the effectiveness of bariatric surgery in improving eGFR among African American patients. We hypothesize that bariatric surgery is associated with improved post-operative kidney function among African Americans.
Methods: We conducted a retrospective analysis of patients who underwent bariatric surgery (roux-en-y gastric bypass and sleeve gastrectomy) between 2008 and 2013. We measured pre- and post-operative BMI and eGFR. Post-operative values were recorded 6 months following surgery. The eGFR was estimated by calculating creatinine clearance (CKD-EPI equation used), and a range of 90-125 ml/min/1.73m2 was considered normal. We categorized patients into three BMI categories – ‘35 ≥ BMI < 40′, ‘40 ≥ BMI < 50′ and ‘BMI ≥ 50′. We compared pre-operative eGFR to the post-operative values for patients with glomerular hyperfiltration (stage I CKD) and patients at CKD stages II-IV. We also analyzed the proportion of patients whose CKD condition improved to a less severe stage post-operatively.
Results: The results include 160 patients whose mean age at the time of surgery was 43.0 years. The overall mean eGFR was 104.6 ml/min/1.73m2 prior to surgery and rose to 110.0 post-operatively (p > 0.05). The mean BMI reduced from 49.1 kg/m2 pre-operatively to 38.3 kg/m2 post-operatively (p < 0.0001). Of the 160 patients, 28 had glomerular hyperfiltration (eGFR > 125) and 40 had stages II-IV CKD (eGFR 15-90) prior to surgery. The patients with stage I CKD had a mean pre-operative eGFR of 133.3, which reduced to 125.3 post-operatively (p = 0.0036). Among CKD stage I patients only those in the ‘40 ≥ BMI < 50′ BMI category encountered significant reduction in eGFR from 135.3 to 125 (p = 0.0258). Patients with stages II-IV CKD had a lower than normal mean pre-operative eGFR of 74.8, which rose to 82.6 post-operatively (p > 0.05). None of the BMI categories for patients with stages II-IV CKD showed significant improvement in kidney function. A stage I CKD resolution rate of 43.8% was seen following bariatric surgery, while 57.1% of patients at stages II-IV CKD improved to less severe stages following surgery.
Conclusion: African American patients experienced an improvement in their renal function following bariatric surgery. Further follow up is necessary to determine the effects of bariatric surgery on long-term renal function among African Americans.