Renal Outcomes 1 Year After Metabolic Bariatric Surgery in a Multi-ethnic Asian Cohort

Obesity increases the risk of incident chronic kidney disease (CKD) and is one of the strongest risk factors for new-onset CKD even in the absence of metabolic risk factors. Weight loss has been shown to reduce renal hyperfiltration and proteinuria. Metabolic bariatric surgery (MBS) remains an effective treatment for obesity and its metabolic-related complications. However, literature on its impact on renal function remains limited.

This was an observational retrospective study in a tertiary centre in Singapore. MBS cases performed at the centre between 2008 and 2019 were included. The primary outcome measures were estimated glomerular filtration rate (eGFR), calculated using the CKD epidemiology collaboration equation, and albuminuria (defined as urine albumin-creatinine ratio (uACR) > 3.5 mg/mmol) at baseline and 1-year post-MBS.

Five hundred fifty-seven patients were included. One-year post-MBS, median eGFR increased from 110.9 mL/min/1.73 m² (IQR 92.4 to 121.5) to 112.6 mL/min/1.73 m² (IQR 97.3 to 122.3), p < 0.001. Median uACR decreased from 1.00 mg/mmol (IQR 0.40 to 3.55) to 0.70 mg/mmol (IQR 0.40 to 1.80) 1-year post-MBS (p = 0.001). 12.9% of patients had improved CKD staging. The proportion of patients with albuminuria decreased from 24.8% at baseline to 1.89% 1-year post-MBS (p < 0.001). One-year post-MBS, the subgroup with reduced eGFR had significant increases in eGFR (p < 0.001), with a trend towards a reduction in uACR.

MBS had a positive impact on renal function with modest but statistically significant improvement in eGFR and reduction in albuminuria at 1-year post-surgery. Longer-term data is required to investigate the durability of this impact.