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, according to a population-based study in Denmark.
Writing in BMC Nephrology, researchers reported patients with bariatric surgery had an increased 1-year risk for AKI and 10-year risk for nephrolithiasis, alongside a decreased 10-year risk for CKD (stages G3-5) and KFRT, compared with matched patients diagnosed with overweight/obesity who did not undergo surgery.
A Closer Look
Using national registry data, the team identified all adults who underwent Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG) between January 1, 2006, and December 31, 2018. Each patient was age- and sex-matched (1:5) to patients with hospital-diagnosed overweight/obesity without bariatric surgery. Researchers also compared results against a population cohort matched solely by age and sex. Outcomes included cumulative risks for AKI, nephrolithiasis, CKD (G3-G5), and KFRT.
The cohort comprised 18,827 surgical patients (17,200 RYGB and 1627 SG) and 94,135 matched comparators. Median age was 41 years, 76% were women, and the median follow-up was 8.1 years. At baseline, the median estimated glomerular filtration rate (eGFR) was comparable (103 mL/min/1.73 m2) between both surgery and overweight/obesity control groups, as were A1c levels. There were fewer comorbidities in the population cohort matched only by age and sex than in the overweight/obesity comparison cohort.
Using multivariable Cox regression analyses, the researchers found the 1-year risk for AKI following bariatric surgery was 2.7%. At 10 years, risks were 3.5% for nephrolithiasis, 0.4% for CKD, and 0.2% for KFRT.
Adjusted hazard ratios (HRs) after bariatric surgery vs without bariatric surgery were higher for AKI (HR, 1.63) and nephrolithiasis (HR, 1.73) and lower for CKD (HR, 0.41) and KFRT (HR, 0.63). Results were consistent when compared against the population cohort.
By procedure, the 1-year AKI risk was 2.7% after RYGB and 2.4% after SG vs 2.5% in the overweight/obesity cohort and 1.1% in the population cohort. At 10 years, the risk for incident nephrolithiasis was 3.6% after RYGB and 1.2% after SG vs 2.4% and 1.3% in the overweight/obese and population cohorts, respectively. KFRT risk at 10 years was 0.2% after RYGB and 1.6% after SG vs 0.4% and 0.1% in the overweight/obesity and population cohorts, respectively.
“The increased short-term risk of AKI and nephrolithiasis was expected, given the physiological changes after bariatric surgery, but the long-term reduction in CKD and KFRT was both encouraging and clinically important,” said study investigator Christian Goul Sørensen, MD, Department of Clinical Epidemiology, Department of Clinical Medicine, Aarhus University and Aarhus University Hospital, Aarhus, Denmark. “It was also noteworthy that the results were consistent not only in the obesity-matched comparison cohort but also in the cohort matched solely on age and sex, which further strengthens the validity of our findings.”
RYGB and SG are known to help mitigate obesity-associated complications, such as hypertension, hyperlipidemia, and type 2 diabetes. Studies have suggested that there are improvements in eGFR after bariatric surgery. However, long-term evidence from routine clinical care has not been well studied. Furthermore, RYGB may lead to AKI due to a combination of preoperative, intraoperative, and postoperative factors.
“Obesity is a major driver of kidney disease, often in combination with comorbidities such as diabetes and hypertension,” Sorensen told GI & Hepatology News. “Patients and clinicians face complex decisions about surgery, and understanding both the short-term surgical risks and the long-term kidney benefits is crucial for informed counseling. As bariatric surgery becomes increasingly common worldwide, population-based evidence like this helps guide clinical practice and supports shared decision-making with patients.”
Consistent With Clinical Experience
Panduranga S. Rao, MD, professor of nephrology at the University of Michigan, Ann Arbor, Michigan, who was not involved in the study, called the results consistent with prior clinical experience. He highlighted the strong follow-up and detailed lab and comorbidity data, while noting that the decreasing use of RYGB may limit applicability going forward.
“However, one has to remain vigilant to the risk of nephrolithiasis in the patients who have undergone Roux-en-Y in the past,” he said.
The observation of decreasing risk for CKD with weight loss is particularly relevant, given the growing use of GLP-1s for weight loss, Rao added.
Srinivasan Beddhu, MD, professor of internal medicine and the scientific director of the Cardio-Renal & Metabolism Center at the University of Utah Health in Salt Lake City, said the large national cohort design and outcomes data offer further reassurance about the long-term kidney health effects of bariatric surgery.
“The message that the risks of AKI and nephrolithiasis are outweighed by the long-term kidney protective effects of bariatric surgery is important,” said Beddhu.
Alexander Chang, MD, associate professor and a practicing nephrologist at the Geisinger Health System in Danville, Pennsylvania, noted that the study provided more evidence about RYGB-associated kidney stone risk via fat malabsorption, which raises the levels of fatty acids that bind dietary calcium.
“Calcium normally precipitates with dietary oxalate, and thus, there can be an increase in urinary oxalate,” Chang explained. “There did not appear to be increased risk of nephrolithiasis with sleeve gastrectomy, consistent with other studies.
“This study emphasizes the importance of multidisciplinary care post-bariatric surgery to try to prevent complications such as kidney stones,” Chang added. “This can be tricky but requires trying different strategies to increase fluid intake and calcium citrate supplements with meals.”
The study was partly funded by a grant from the Novo Nordisk Foundation and the Independent Research Fund Denmark. One author reported receiving a speaking fee support from Novo Nordisk for conference attendance. The other authors declared no competing interests. Sørensen, Rao, Beddhu, and Chang had no financial disclosures.
A version of this article appeared on Medscape.com.
, according to a population-based study in Denmark.
Writing in BMC Nephrology, researchers reported patients with bariatric surgery had an increased 1-year risk for AKI and 10-year risk for nephrolithiasis, alongside a decreased 10-year risk for CKD (stages G3-5) and KFRT, compared with matched patients diagnosed with overweight/obesity who did not undergo surgery.
A Closer Look
Using national registry data, the team identified all adults who underwent Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG) between January 1, 2006, and December 31, 2018. Each patient was age- and sex-matched (1:5) to patients with hospital-diagnosed overweight/obesity without bariatric surgery. Researchers also compared results against a population cohort matched solely by age and sex. Outcomes included cumulative risks for AKI, nephrolithiasis, CKD (G3-G5), and KFRT.
The cohort comprised 18,827 surgical patients (17,200 RYGB and 1627 SG) and 94,135 matched comparators. Median age was 41 years, 76% were women, and the median follow-up was 8.1 years. At baseline, the median estimated glomerular filtration rate (eGFR) was comparable (103 mL/min/1.73 m2) between both surgery and overweight/obesity control groups, as were A1c levels. There were fewer comorbidities in the population cohort matched only by age and sex than in the overweight/obesity comparison cohort.
Using multivariable Cox regression analyses, the researchers found the 1-year risk for AKI following bariatric surgery was 2.7%. At 10 years, risks were 3.5% for nephrolithiasis, 0.4% for CKD, and 0.2% for KFRT.
Adjusted hazard ratios (HRs) after bariatric surgery vs without bariatric surgery were higher for AKI (HR, 1.63) and nephrolithiasis (HR, 1.73) and lower for CKD (HR, 0.41) and KFRT (HR, 0.63). Results were consistent when compared against the population cohort.
By procedure, the 1-year AKI risk was 2.7% after RYGB and 2.4% after SG vs 2.5% in the overweight/obesity cohort and 1.1% in the population cohort. At 10 years, the risk for incident nephrolithiasis was 3.6% after RYGB and 1.2% after SG vs 2.4% and 1.3% in the overweight/obese and population cohorts, respectively. KFRT risk at 10 years was 0.2% after RYGB and 1.6% after SG vs 0.4% and 0.1% in the overweight/obesity and population cohorts, respectively.
“The increased short-term risk of AKI and nephrolithiasis was expected, given the physiological changes after bariatric surgery, but the long-term reduction in CKD and KFRT was both encouraging and clinically important,” said study investigator Christian Goul Sørensen, MD, Department of Clinical Epidemiology, Department of Clinical Medicine, Aarhus University and Aarhus University Hospital, Aarhus, Denmark. “It was also noteworthy that the results were consistent not only in the obesity-matched comparison cohort but also in the cohort matched solely on age and sex, which further strengthens the validity of our findings.”
RYGB and SG are known to help mitigate obesity-associated complications, such as hypertension, hyperlipidemia, and type 2 diabetes. Studies have suggested that there are improvements in eGFR after bariatric surgery. However, long-term evidence from routine clinical care has not been well studied. Furthermore, RYGB may lead to AKI due to a combination of preoperative, intraoperative, and postoperative factors.
“Obesity is a major driver of kidney disease, often in combination with comorbidities such as diabetes and hypertension,” Sorensen told GI & Hepatology News. “Patients and clinicians face complex decisions about surgery, and understanding both the short-term surgical risks and the long-term kidney benefits is crucial for informed counseling. As bariatric surgery becomes increasingly common worldwide, population-based evidence like this helps guide clinical practice and supports shared decision-making with patients.”
Consistent With Clinical Experience
Panduranga S. Rao, MD, professor of nephrology at the University of Michigan, Ann Arbor, Michigan, who was not involved in the study, called the results consistent with prior clinical experience. He highlighted the strong follow-up and detailed lab and comorbidity data, while noting that the decreasing use of RYGB may limit applicability going forward.
“However, one has to remain vigilant to the risk of nephrolithiasis in the patients who have undergone Roux-en-Y in the past,” he said.
The observation of decreasing risk for CKD with weight loss is particularly relevant, given the growing use of GLP-1s for weight loss, Rao added.
Srinivasan Beddhu, MD, professor of internal medicine and the scientific director of the Cardio-Renal & Metabolism Center at the University of Utah Health in Salt Lake City, said the large national cohort design and outcomes data offer further reassurance about the long-term kidney health effects of bariatric surgery.
“The message that the risks of AKI and nephrolithiasis are outweighed by the long-term kidney protective effects of bariatric surgery is important,” said Beddhu.
Alexander Chang, MD, associate professor and a practicing nephrologist at the Geisinger Health System in Danville, Pennsylvania, noted that the study provided more evidence about RYGB-associated kidney stone risk via fat malabsorption, which raises the levels of fatty acids that bind dietary calcium.
“Calcium normally precipitates with dietary oxalate, and thus, there can be an increase in urinary oxalate,” Chang explained. “There did not appear to be increased risk of nephrolithiasis with sleeve gastrectomy, consistent with other studies.
“This study emphasizes the importance of multidisciplinary care post-bariatric surgery to try to prevent complications such as kidney stones,” Chang added. “This can be tricky but requires trying different strategies to increase fluid intake and calcium citrate supplements with meals.”
The study was partly funded by a grant from the Novo Nordisk Foundation and the Independent Research Fund Denmark. One author reported receiving a speaking fee support from Novo Nordisk for conference attendance. The other authors declared no competing interests. Sørensen, Rao, Beddhu, and Chang had no financial disclosures.
A version of this article appeared on Medscape.com.
, according to a population-based study in Denmark.
Writing in BMC Nephrology, researchers reported patients with bariatric surgery had an increased 1-year risk for AKI and 10-year risk for nephrolithiasis, alongside a decreased 10-year risk for CKD (stages G3-5) and KFRT, compared with matched patients diagnosed with overweight/obesity who did not undergo surgery.
A Closer Look
Using national registry data, the team identified all adults who underwent Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG) between January 1, 2006, and December 31, 2018. Each patient was age- and sex-matched (1:5) to patients with hospital-diagnosed overweight/obesity without bariatric surgery. Researchers also compared results against a population cohort matched solely by age and sex. Outcomes included cumulative risks for AKI, nephrolithiasis, CKD (G3-G5), and KFRT.
The cohort comprised 18,827 surgical patients (17,200 RYGB and 1627 SG) and 94,135 matched comparators. Median age was 41 years, 76% were women, and the median follow-up was 8.1 years. At baseline, the median estimated glomerular filtration rate (eGFR) was comparable (103 mL/min/1.73 m2) between both surgery and overweight/obesity control groups, as were A1c levels. There were fewer comorbidities in the population cohort matched only by age and sex than in the overweight/obesity comparison cohort.
Using multivariable Cox regression analyses, the researchers found the 1-year risk for AKI following bariatric surgery was 2.7%. At 10 years, risks were 3.5% for nephrolithiasis, 0.4% for CKD, and 0.2% for KFRT.
Adjusted hazard ratios (HRs) after bariatric surgery vs without bariatric surgery were higher for AKI (HR, 1.63) and nephrolithiasis (HR, 1.73) and lower for CKD (HR, 0.41) and KFRT (HR, 0.63). Results were consistent when compared against the population cohort.
By procedure, the 1-year AKI risk was 2.7% after RYGB and 2.4% after SG vs 2.5% in the overweight/obesity cohort and 1.1% in the population cohort. At 10 years, the risk for incident nephrolithiasis was 3.6% after RYGB and 1.2% after SG vs 2.4% and 1.3% in the overweight/obese and population cohorts, respectively. KFRT risk at 10 years was 0.2% after RYGB and 1.6% after SG vs 0.4% and 0.1% in the overweight/obesity and population cohorts, respectively.
“The increased short-term risk of AKI and nephrolithiasis was expected, given the physiological changes after bariatric surgery, but the long-term reduction in CKD and KFRT was both encouraging and clinically important,” said study investigator Christian Goul Sørensen, MD, Department of Clinical Epidemiology, Department of Clinical Medicine, Aarhus University and Aarhus University Hospital, Aarhus, Denmark. “It was also noteworthy that the results were consistent not only in the obesity-matched comparison cohort but also in the cohort matched solely on age and sex, which further strengthens the validity of our findings.”
RYGB and SG are known to help mitigate obesity-associated complications, such as hypertension, hyperlipidemia, and type 2 diabetes. Studies have suggested that there are improvements in eGFR after bariatric surgery. However, long-term evidence from routine clinical care has not been well studied. Furthermore, RYGB may lead to AKI due to a combination of preoperative, intraoperative, and postoperative factors.
“Obesity is a major driver of kidney disease, often in combination with comorbidities such as diabetes and hypertension,” Sorensen told GI & Hepatology News. “Patients and clinicians face complex decisions about surgery, and understanding both the short-term surgical risks and the long-term kidney benefits is crucial for informed counseling. As bariatric surgery becomes increasingly common worldwide, population-based evidence like this helps guide clinical practice and supports shared decision-making with patients.”
Consistent With Clinical Experience
Panduranga S. Rao, MD, professor of nephrology at the University of Michigan, Ann Arbor, Michigan, who was not involved in the study, called the results consistent with prior clinical experience. He highlighted the strong follow-up and detailed lab and comorbidity data, while noting that the decreasing use of RYGB may limit applicability going forward.
“However, one has to remain vigilant to the risk of nephrolithiasis in the patients who have undergone Roux-en-Y in the past,” he said.
The observation of decreasing risk for CKD with weight loss is particularly relevant, given the growing use of GLP-1s for weight loss, Rao added.
Srinivasan Beddhu, MD, professor of internal medicine and the scientific director of the Cardio-Renal & Metabolism Center at the University of Utah Health in Salt Lake City, said the large national cohort design and outcomes data offer further reassurance about the long-term kidney health effects of bariatric surgery.
“The message that the risks of AKI and nephrolithiasis are outweighed by the long-term kidney protective effects of bariatric surgery is important,” said Beddhu.
Alexander Chang, MD, associate professor and a practicing nephrologist at the Geisinger Health System in Danville, Pennsylvania, noted that the study provided more evidence about RYGB-associated kidney stone risk via fat malabsorption, which raises the levels of fatty acids that bind dietary calcium.
“Calcium normally precipitates with dietary oxalate, and thus, there can be an increase in urinary oxalate,” Chang explained. “There did not appear to be increased risk of nephrolithiasis with sleeve gastrectomy, consistent with other studies.
“This study emphasizes the importance of multidisciplinary care post-bariatric surgery to try to prevent complications such as kidney stones,” Chang added. “This can be tricky but requires trying different strategies to increase fluid intake and calcium citrate supplements with meals.”
The study was partly funded by a grant from the Novo Nordisk Foundation and the Independent Research Fund Denmark. One author reported receiving a speaking fee support from Novo Nordisk for conference attendance. The other authors declared no competing interests. Sørensen, Rao, Beddhu, and Chang had no financial disclosures.
A version of this article appeared on Medscape.com.