Renal Function in Patients after Metabolic and Bariatric Surgery.

BACKGROUND

Obesity is not only a risk factor for chronic kidney disease (CKD) but also accelerates its progression. Metabolic bariatric surgery has been shown to improve the course of CKD significantly. This study aims to explore the impact of metabolic bariatric surgery on renal function from various angles, including pre- and post-operative comparisons, differences between surgical techniques, and subgroup analyses based on kidney function.

METHODS

We analyzed the outcomes of patients who underwent Roux-en-Y gastric bypass (RYGB) or laparoscopic Sleeve Gastrectomy (LSG) between January 2020 and May 2023 from the prospectively managed database in our hospital. Patients were grouped based on baseline glomerular filtration rate (GFR): hyperfiltration (GFR > 125 mL/min), normal (GFR 125-90 mL/min), CKD stage 2 (GFR 89-60 mL/min), and CKD stage 3 (GFR 59-30 mL/min). Pre- and post-operative outcomes were compared, and subgroup analyses were conducted.

RESULTS

A total of 278 patients were included in the study, with 74.1% undergoing LSG. The cohort was 59.7% female, with an average BMI of 38.3 ± 8.47 kg/m and a mean age of 32.9 ± 9.54 years. Post-operative GFR slightly increased from 115 ± 14.8 mL/min pre-surgery to 118 ± 15.4 mL/min post-surgery. Significant improvements in weight, blood glucose, lipid levels, and blood pressure were also observed. Both RYGB and LSG groups showed significant improvements in renal function post-operatively, with GFR decreasing from 115 ± 18.8 mL/min to 112 ± 16.6 mL/min in the RYGB group and from 119 ± 13.9 mL/min to 115 ± 18.8 mL/min in the LSG group. However, there was no significant difference between the two groups in renal function improvement (P > 0.05). In subgroup analyses, hyperfiltration was present in 29.1% of patients and CKD in 5%. In the hyperfiltration group, GFR decreased from 134 ± 5.49 mL/min to 127 ± 8.46 mL/min, with 40.7% of patients returning to normal GFR levels. However, 8.7% of patients in the normal group developed hyperfiltration, and 4.9% showed signs of renal impairment. Among patients with CKD stage 2 or 3, renal function improved in 50% of cases. Linear regression analysis showed that age, hypertension status, and serum urea levels were significantly associated with postoperative GFR levels (P < .05).

CONCLUSIONS

Metabolic bariatric surgery positively impacts renal function one year post-operatively. Preoperative attention to age, hypertension status, and serum urea levels may positively influence patient outcomes. In addition, the potential for postoperative renal insufficiency should be considered, and regular follow-up assessments are essential. Early identification and treatment of abnormalities are crucial for optimizing outcomes.