Does Bariatric Surgery Improve Kidney Function in obese Patients? A Cohort Study

Introduction: Obesity is a global epidemic that may cause renal dysfunction. Weight loss in the postoperative follow-up of bariatric surgery may improve renal function in these patients. Thus, the purpose of this study was to give insight on the subject using a sensible biomarker: cystatin C. Materials and methods: This cohort was performed in the Obesity Department from Campina Grande – Paraiba, Brazil. It was recruited 35 obese (25 women and 10 men) who underwent bariatric surgery with follow-up of at least one year. The ages ranged from 24 and 57 years. Those with thyroid disease and with microalbuminuria ≥ 30mg/g were excluded. Serum levels of creatinine and cystatin C were measured, and the glomerular filtration rate (GFR) was estimated using the CKD Epi (Chronic Kidney Disease Epidemiology Collaboration) equation creatinine- cystatin C. The investigation was approved by the Ethics Committee. The sample was of convenience. Quantitative variables were expressed by the mean and standard deviation. Paired tests were used for assessing difference between means. Chi square test and exact Fisher were used for difference among frequencies. p ≤ 0.05 was used for rejecting the null hypothesis. Results:The most frequent associated morbidities were: sexual dysfunction (n = 17 – 48.5%); hypertension (n =15 – 42.8%); type II diabetes (n =13 – 37.1%); anxiety (n = 14 – 40.0%); and depression (n = 12 – 34.2%). Twenty-three (65.7%) patients underwent sleeve technique and 12 (34.2%) bypass surgery. It was observed a significant reduction in the mean of body mass index (BMI) in the post-operative follow-up – p < 0.0001. The mean concentrations of cystatin C were similar, regarding to pre- and post-operative periods – p = 0.1614. There was a significant improvement of glomerular filtration rates - p= 0.0091. The improvement of renal function was more significant among those who underwent sleeve surgery as compared to bypass - p = 0.0008. Conclusion: It was observed improvement of the majority of morbidities after bariatric surgery, as well as renal function, in obese individuals. Despite these results, larger and longer-term outcome cohorts are required for better answer of the main purpose of this health issue.