Effect of weight loss after bariatric surgery on kidney function in a multiethnic Asian population.

BACKGROUND

Current literature reports improvement in kidney function in obese patients after bariatric surgery in non-Asian centers. It is unclear how kidney function is affected by postoperative body composition changes in obese Asian patients.

OBJECTIVES

To evaluate kidney function and its relationship to body composition in a multiethnic Asian population after bariatric surgery.

SETTING

This study was performed in a university hospital.

METHODS

Data of 68 obese patients who were followed for 1 year after surgery were retrieved from our university hospital clinical care database. Body composition was obtained by bioimpedance analysis. Kidney function was calculated as glomerular filtration rate (GFR) using the following formulas: (1) Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) (estimated GFR [eGFR], mL/min/1.73 m(2)); (2) absolute GFR (aGFR, mL/min); and (3) lean weight-adjusted Cockcroft-Gault creatinine clearance (CG-LBW, mL/min). Patients were further examined by 2 subgroups: eGFR<90 and>90 mL/min/1.73 m(2).

RESULTS

One year after surgery, body mass index (BMI) declined from 41.9±5.7 to 29.6±4.2 kg/m(2) (P<.001), body surface area (BSA) decreased from 2.15±0.23 to 1.86±0.18 m(2) (P<.001), and fat mass (FM) reduced from 45.8±9.4 to 25.6±10.5 kg (P<.001). There were significant differences in percentage excess weight loss (%EWL) among Chinese, Malays, Indians, and other ethnicities. Similar results were found with percentage fat mass loss (%FML). Changes in aGFR were associated with reductions in FM (P = .010), BSA (P = .049), and %EWL (P<.001). In the eGFR>90 subgroup, eGFR decreased from 143±22 to 122±19 mL/min/1.73 m(2). Conversely, in the eGFR<90 subgroup, eGFR had a trend of improvement from 69 to 79 mL/min/1.73 m(2).

CONCLUSION

Changes in eGFR after bariatric surgery in the obese Asian patient are strongly associated with reduction in FM, BSA, and %EWL. More work is required to investigate if certain ethnicities have better postoperative renal profiles.