Kidney outcomes after bariatric surgery: a population-based cohort study

Abstract Background Bariatric surgery may mitigate obesity-related chronic kidney disease (CKD) but may concurrently increase the risk of acute kidney injury (AKI) and hyperoxaluria. We examined kidney outcomes after bariatric surgery. Methods Using population-based registries, we included individua...

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Main Authors: Christian Goul Sørensen, Simon Kok Jensen, Reimar Wernich Thomsen, Bente Jespersen, Sigrid Bjerge Gribsholt, Christian Fynbo Christiansen
Format: Article
Language:English
Published: BMC 2025-08-01
Series:BMC Nephrology
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Online Access:https://doi.org/10.1186/s12882-025-04378-8
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author Christian Goul Sørensen
Simon Kok Jensen
Reimar Wernich Thomsen
Bente Jespersen
Sigrid Bjerge Gribsholt
Christian Fynbo Christiansen
author_facet Christian Goul Sørensen
Simon Kok Jensen
Reimar Wernich Thomsen
Bente Jespersen
Sigrid Bjerge Gribsholt
Christian Fynbo Christiansen
author_sort Christian Goul Sørensen
collection DOAJ
description Abstract Background Bariatric surgery may mitigate obesity-related chronic kidney disease (CKD) but may concurrently increase the risk of acute kidney injury (AKI) and hyperoxaluria. We examined kidney outcomes after bariatric surgery. Methods Using population-based registries, we included individuals with Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG) in Denmark between 2006 and 2018. These were age- and sex-matched 1:5 to individuals with hospital-diagnosed overweight/obesity without bariatric surgery. Cumulative incidences (risks) of AKI, nephrolithiasis, CKD (stage G3–G5), and kidney failure with replacement therapy (KFRT) were computed, accounting for the competing risk of death. Cox regression was used to estimate hazard ratios (HR) adjusted for age, sex, and comorbidity. Results We included 18,827 individuals with bariatric surgery (17,200 RYGB and 1,627 SG) and 94,135 individuals in the matched overweight/obesity cohort (median age 41 years, median follow-up 8.1 years). The one-year risk of AKI following bariatric surgery was 2.7%, while the ten-year risks of nephrolithiasis, CKD, and KFRT were 3.5%, 0.4%, and 0.2%, respectively. When comparing individuals with bariatric surgery with those with overweight/obesity, the adjusted HRs were increased at 1.63 (95% CI; 1.38, 1.92) for AKI and 1.73 (95% CI; 1.56, 1.91) for nephrolithiasis. In contrast, adjusted HRs were decreased at 0.41 (95% CI; 0.26, 0.66) for CKD and 0.63 (95% CI; 0.42, 0.95) for KFRT. Similar results were observed versus a population comparison cohort. Conclusions Bariatric surgery was associated with an increased risk of AKI and nephrolithiasis, while long-term risks of CKD and KFRT were lower than in matched individuals with overweight/obesity.
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spelling doaj-art-da9cf59b941b427b95a2cf74c835dbf32025-08-20T03:42:48ZengBMCBMC Nephrology1471-23692025-08-0126111210.1186/s12882-025-04378-8Kidney outcomes after bariatric surgery: a population-based cohort studyChristian Goul Sørensen0Simon Kok Jensen1Reimar Wernich Thomsen2Bente Jespersen3Sigrid Bjerge Gribsholt4Christian Fynbo Christiansen5Department of Clinical Epidemiology, Department of Clinical Medicine, Aarhus University and Aarhus University HospitalDepartment of Clinical Epidemiology, Department of Clinical Medicine, Aarhus University and Aarhus University HospitalDepartment of Clinical Epidemiology, Department of Clinical Medicine, Aarhus University and Aarhus University HospitalDepartment of Renal Medicine, Aarhus University HospitalSteno Diabetes Center Aarhus and Department of Endocrinology and Internal Medicine, Aarhus University HospitalDepartment of Clinical Epidemiology, Department of Clinical Medicine, Aarhus University and Aarhus University HospitalAbstract Background Bariatric surgery may mitigate obesity-related chronic kidney disease (CKD) but may concurrently increase the risk of acute kidney injury (AKI) and hyperoxaluria. We examined kidney outcomes after bariatric surgery. Methods Using population-based registries, we included individuals with Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG) in Denmark between 2006 and 2018. These were age- and sex-matched 1:5 to individuals with hospital-diagnosed overweight/obesity without bariatric surgery. Cumulative incidences (risks) of AKI, nephrolithiasis, CKD (stage G3–G5), and kidney failure with replacement therapy (KFRT) were computed, accounting for the competing risk of death. Cox regression was used to estimate hazard ratios (HR) adjusted for age, sex, and comorbidity. Results We included 18,827 individuals with bariatric surgery (17,200 RYGB and 1,627 SG) and 94,135 individuals in the matched overweight/obesity cohort (median age 41 years, median follow-up 8.1 years). The one-year risk of AKI following bariatric surgery was 2.7%, while the ten-year risks of nephrolithiasis, CKD, and KFRT were 3.5%, 0.4%, and 0.2%, respectively. When comparing individuals with bariatric surgery with those with overweight/obesity, the adjusted HRs were increased at 1.63 (95% CI; 1.38, 1.92) for AKI and 1.73 (95% CI; 1.56, 1.91) for nephrolithiasis. In contrast, adjusted HRs were decreased at 0.41 (95% CI; 0.26, 0.66) for CKD and 0.63 (95% CI; 0.42, 0.95) for KFRT. Similar results were observed versus a population comparison cohort. Conclusions Bariatric surgery was associated with an increased risk of AKI and nephrolithiasis, while long-term risks of CKD and KFRT were lower than in matched individuals with overweight/obesity.https://doi.org/10.1186/s12882-025-04378-8Acute kidney injuryBariatric surgeryChronic kidney diseaseEpidemiologyNephrolithiasisRoux en-Y gastric bypass
spellingShingle Christian Goul Sørensen
Simon Kok Jensen
Reimar Wernich Thomsen
Bente Jespersen
Sigrid Bjerge Gribsholt
Christian Fynbo Christiansen
Kidney outcomes after bariatric surgery: a population-based cohort study
BMC Nephrology
Acute kidney injury
Bariatric surgery
Chronic kidney disease
Epidemiology
Nephrolithiasis
Roux en-Y gastric bypass
title Kidney outcomes after bariatric surgery: a population-based cohort study
title_full Kidney outcomes after bariatric surgery: a population-based cohort study
title_fullStr Kidney outcomes after bariatric surgery: a population-based cohort study
title_full_unstemmed Kidney outcomes after bariatric surgery: a population-based cohort study
title_short Kidney outcomes after bariatric surgery: a population-based cohort study
title_sort kidney outcomes after bariatric surgery a population based cohort study
topic Acute kidney injury
Bariatric surgery
Chronic kidney disease
Epidemiology
Nephrolithiasis
Roux en-Y gastric bypass
url https://doi.org/10.1186/s12882-025-04378-8
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AT bentejespersen kidneyoutcomesafterbariatricsurgeryapopulationbasedcohortstudy
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