The Effects of Bariatric Surgery on Renal Outcomes: a Systematic Review and Meta-analysis.

ABSTRACT

BACKGROUND/OBJECTIVE: Although promising, data regarding the renal impact and safety of bariatric surgery (BS) are insufficient. We aimed at investigating the benefits and harms of BS for weight loss on kidney function. METHODS: A systematic review and meta-analysis of observational studies reporting data about the impact of BS (any techniques) on serum/plasma creatinine, creatinine clearance, glomerular filtration rate (GFR), proteinuria, nephrolithiasis, and need for renal replacement therapy (RRT)) was performed. Obese adults (non-chronic kidney disease (CKD), CKD or transplanted patients) that underwent BS for weight loss were included. After searching MEDLINE (inception to August 2017), the Cochrane Library (Issue 10-12, October 2017), and the websiteclinicaltrials.gov (August 2017), data were extracted and summarized using a random-effects model. RESULTS: The final analysis included 23 cohort studies, comprising 3015 participants. Compared with renal function before treatment, BS significantly decreased serum creatinine level (mean difference (MD), - 0.08 mg dl-1; 95% confidence interval (CI), - 0.10 to - 0.06); p < 0.001) and proteinuria (MD, - 0.04 g 24 h-1; 95% CI, - 0.06 to - 0.02; p < 0.001) in the overall group. GFR significantly improved 6 months or more after BS both in the hyperfiltration and CKD subgroups. Renal function also tended to improve in renal transplant patients. Data on nephrolithiasis and the need for RRT were scarce or not reported. CONCLUSIONS: BS apparently has positive effects on kidney function and tends to normalize GFR across different categories of renal impairment (hyperfiltration and CKD patients).