BACKGROUND: Obesity is a significant risk factor for chronic kidney disease (CKD), with metabolic bariatric surgery offering potential renal benefits. However, there is limited comparative data on the impact of Roux-en-Y gastric bypass (RYGB) versus laparoscopic sleeve gastrectomy (LSG) on renal function in individuals with obesity without end-stage renal disease (ESRD). The objective of this study was to compare renal function outcomes following RYGB and LSG in patients with obesity, focusing on estimated glomerular filtration rate (eGFR), serum creatinine, albumin-creatinine ratio (ACR), and serum cystatin C. METHODS: A systematic review and meta-analysis were conducted following Cochrane and PRISMA guidelines. Data from 17 observational studies (n = 3339) were analyzed. Primary outcomes included changes in eGFR, ACR, serum creatinine, and cystatin C. Secondary outcomes included excess weight loss (%EWL) and total weight loss (%TWL). Statistical analysis involved fixed and random-effects models based on heterogeneity levels. RESULTS: RYGB demonstrated significant improvements in eGFR (SMD = - 0.71
95% CI - 0.89 to - 0.52, p <
0.00001) and serum cystatin C (MD = - 0.10
95% CI - 0.17 to - 0.03, p = 0.004) compared to LSG. No significant differences were found for serum creatinine (MD = - 1.06
95% CI - 4.42 to 2.30, p = 0.54) or ACR (MD = 1.95
95% CI - 0.39 to 4.29, p = 0.10). RYGB also showed greater long-term weight loss, particularly at 5 years (%EWL: MD = 22.00
95% CI 6.56 to 37.44, p = 0.005). CONCLUSIONS: RYGB offers similar renal improvements with superior weight loss compared to LSG in individuals with obesity without ESRD. These findings emphasize the need for personalized treatment approaches and further research to validate these outcomes.