Purpose: This study aims to assess the long-term renal effects of bariatric surgery (BS) in severely obese patients over a follow-up period of up to 11 years.
Materials and methods: In a retrospective cohort study including 102 patients, patients were stratified by eGFR at baseline and divided into three groups: (1) reduced, (2) normal, and (3) increased filtration rate. Adjustments for age- and sex-related decline in eGFR were performed. We used uni- and multivariate regression analysis to identify variables that were thought to determine change in eGFR.
Results: Over a median follow-up of 8.5 years (interquartile range 2.7), eGFR declined from 96.1 ± 20.7 to 84.9 ± 21.0 ml/min (p < 0.001). Among patients with (1), eGFR remained stable (69.1 ± 19.3 ml/min). Among patients with (2), eGFR declined from 99.7 ± 13.3 ml/min to 88.7 ± 19.4 ml/min (p < 0.001). Among patients with (3), eGFR decreased to normal levels (94.2 ± 17.7 ml/min, p < 0.001). Age- and sex-adjusted eGFR increased (6.4 ± 14.4 ml/min; p < 0.05) among patients with reduced filtration rate. Among patients with normal filtration rate, adjusted eGFR remained stable during follow-up (-1.3 ± 15.2 ml/min; n.s.). Among patients with increased filtration rate, adjusted eGFR decreased and remained within the normal range (-13.2 ± 12.2 ml/min; p < 0.001). Change in eGFR showed a negative correlation with eGFR at baseline (B = -0.31; p < 0.001), change in LDL-cholesterol (B = -0.09; p < 0.05), and a negative correlation with treatment requiring hypertension (B = -9.36; p = 0.001).
Conclusion: BS is protective against renal function decline in severely obese patients in the long term.
Keywords: Bariatric surgery; Glomerular filtration rate; Long-term; Obesity; Renal function.