Impact of bariatric surgery on renal function

Introduction
Bariatric surgery offers superior benefits for weight loss, quality of life and a spectrum of metabolic diseases. Despite these benefits, studies so far have shown varying results on its effect on renal function.

Aim
In this study, we aim to look at bariatric surgery’s effect on renal function at one, two and three year post operation (post-op).

Methods
This is a retrospective cross-sectional single-center study of patients who underwent bariatric surgery between 11/2008 and 06/2018. Renal function was calculated by using Cockroft-Gault equation, expressed as Creatinine Clearance (CrCl). Statistical analysis used was one-way ANOVA (Welch’s) with Games-Howell Post-Hoc Test.

Results
From 307 patients who underwent bariatric surgery within the time period, 145 were studied. 30.3% (n=44) were male. The average age and body mass index (BMI) at referral were 48.1±8.6 years and 47.96±7.9 kgm-2 respectively, while the average age and BMI at surgery were 49.1±8.8 years and 40.62±4.2 kgm-2 respectively. Mean CrCl at surgery, year 1, year 2, and year 3 post-op were 172.35±53.29 mL/min, 179.20±57.87 mL/min, 142.35±46.05 mL/min, and 119.56±42.46 mL/min. Marginal improvement of CrCl at year one post-op (172.35±53.29mL/min to 179.20±57.87mL/min) was statistically insignificant (p=0.731). Meanwhile, there was statistically significant CrCl decline observed from year 1 to year 3 post-op (p<0.001).

Conclusion
Statistically insignificant marginal improvement in CrCl at year one post-op was noted. Beyond this, there was steady CrCl decline, albeit remained higher than the lower limit for respective gender. We recommend for further studies that take into account additional factors affecting renal function.