Metabolic bariatric surgery shows lasting benefits

The beneficial effects of metabolic bariatric surgery are long-lasting, with improvements in renal function and reductions in albuminuria still apparent 1 year after the procedure, according to a Singapore study presented at the recently concluded ENDO 2021 virtual conference by the Endocrine Society.

“Obesity increases the risk of incident chronic kidney disease (CKD), being one of the strongest risk factors for new-onset CKD even in the metabolically normal obese,” the researchers said.

“Weight loss has been shown to reduce renal hyperfiltration and proteinuria. Metabolic Bariatric Surgery remains an effective treatment for obesity and its metabolic related complications,” though its long-term impacts have yet to be elucidated in the literature, they added.

The present study aimed to determine the 1-year stability of metabolic bariatric surgery in 557 patients (mean age 41.7±10.1 years, 65.4 percent women) who had undergone the procedure at the Singapore General Hospital from 2008 to 2019. Patient information were retrospectively analysed for the primary outcome measures of estimated glomerular filtration rate (eGFR) and albuminuria. Measurements were collected at baseline and at 1 year after.

Most (52.1 percent) of the participants were nondiabetic; 34.5 percent had diabetes mellitus, while 13.5 percent were prediabetic. In terms of hypertension status, 55.2 percent of patients were hypertensive and 42.9 percent were normotensive. The median eGFR was 110.9 mL/min/1.73 m², and the median urinary albumin-creatinine ratio (uACR) was 1.00 mg/mmol. [ENDO 2021, abstract P02-23]

At the time of surgery, mean body mass index (BMI) was 42.5±7.9 kg/m², which significantly dropped by 11.3±4.2 kg/m² by the 1-year follow-up. Similarly, systolic (–3.24±19.3 mm Hg) and diastolic (–5.23±13.8 mm Hg) were significantly reduced a year after the surgery.

The researchers also detected significantly lowered fasting glucose levels (–1.95±2.89 mmol/L), along with a significant increase in high-density lipoprotein concentrations (0.29±0.26 mmol/L). At follow-up, median eGFR likewise significantly improved by 1.66 mL/min/1.73 m² (p<0.001).

Stratifying patients according to glycaemic status did not alter the main findings, showing that improvements in eGFR were present in both prediabetic and nondiabetic participants. Similarly, there was a decrease in median uACR after 1 year (0.30 mg/mmol; p=0.001), which also remained significant in diabetics and prediabetics.

The proportion of patients on antihypertensive (48.8 percent to 14.4 percent), antidiabetic (34.1 percent to 12.7 percent, and lipid-lowering (37.8 percent to 20.4 percent) medications also decreased significantly 1 year after metabolic bariatric surgery. In particular, the use of angiotensin converting enzyme inhibitors and/or angiotensin receptor blockers dropped to 9.2 percent at follow up from 32.9 percent at baseline (p<0.001).

Overall, 12.9 percent of the patients saw an improvement in their CKD ratings, and the prevalence of albuminuria dropped to 1.89 percent at 1-year post-surgery, down significantly from 24.8 percent at baseline (p<0.001).

“Metabolic bariatric surgery had a positive impact on renal function as shown by the improvement in eGFR in the nondiabetic group, and the reduction in albuminuria in the diabetes and prediabetes group at 1-year post surgery,” the researchers said. “More adequately powered, longer-term data is required to investigate the durability of this impact.”