The Impact of Early-Stage Chronic Kidney Disease on Weight Loss Outcomes After Gastric Bypass

Purpose Weight loss achieved through bariatric metabolic surgery was demonstrated to be effective at reversing chronic kidney dysfunction associated with obesity-related glomerulopathy. However, robust data on how pre-operative kidney status impacts on bariatric metabolic surgery weight loss outcomes is still lacking. The aim of this study was to evaluate the impact of kidney dysfunction on weight loss outcomes after bariatric metabolic surgery. Methods Patients with obesity to be submitted to gastric bypass surgery underwent a pre-operative evaluation of creatinine clearance, estimated glomerular filtration rate (eGFR), proteinuria, and albuminuria in 24-hour urine. Body mass index (BMI), % total weight loss (%TWL), and % excess BMI loss (%EBMIL) were assessed at 6 and 12 months after surgery. Results Before surgery, patients ( N =127) had a mean BMI of 39.6 ± 3.0 kg/m 2 , and 56.7% ( n =72) had a creatinine clearance > 130 mL/min, 23.6% ( n = 30) presented proteinuria > 150 mg/24h, and 15.0% ( n = 19) presented albuminuria > 30 mg/24h. After surgery, the mean BMI was 27.7 kg/m 2 and 25.0 kg/m 2 at 6 and 12 months, respectively ( p <0.0001). The %TWL was lower in patients with pre-operative eGFR < percentile 25 (34.4 ± 5.8% vs 39.4 ± 4.9%, p =0.0007, at 12 months). There were no significant correlations between weight loss metrics and pre-operative creatinine clearance rate, proteinuria, or albuminuria. Conclusion Early-stage chronic kidney disease (G2) has a negative impact on short-term weight loss outcomes after bariatric metabolic surgery, albeit in a magnitude inferior to the clinically relevant threshold. Graphical abstract