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The Role of Bariatric Surgery in Prevention of Kidney Disease Progression in Moderately Obese Patients With Type 2 Diabetes

The Role of Bariatric Surgery in Prevention of Kidney Disease Progression in Moderately Obese... To the Editor We write regarding the article by Cohen et al, “Effect of Gastric Bypass vs Best Medical Treatment on Early-Stage Chronic Kidney Disease in Patients With Type 2 Diabetes and Obesity: A Randomized Clinical Trial.”1 This article was recently discussed at CRAMSURG, an online journal club based in the United Kingdom. We congratulate the authors for their efforts in performing this randomized clinical trial on a relevant and significant problem. We discussed a number of issues that we would like to raise. Although relevant clinical outcomes, such as blood pressure and glycemic control, and patient-centered outcomes, such as quality of life, have been assessed, it is not clear why microalbuminuria has been chosen as the primary outcome. Obesity and weight change have indirect effects on kidney function and microalbuminuria by their impact on diabetes and hypertension. The choice of microalbuminuria as a primary outcome is therefore not clear. This is particularly problematic given that this outcome is subject to misclassification (as acknowledged by the authors) and the randomization process does not address problems associated with the definition of the primary outcome. On this basis, a more appropriate primary outcome would have been a direct clinical outcome such as glycemic control. It appears that 21 of the patients did not meet eligibility criteria but were still included in the trial. Although this is noted in the supplementary documentation, it may not have been clear to all readers. Is it possible that this deviation may have introduced significant selection bias that has significant potential to affect the study results (and increase type I error)? The implications of interim analyses and reporting of outcomes may be significant. If the results are convincing, would the investigators now offer surgery (which appears clearly superior with regards to the primary and several other outcomes) to patients in the “best medical treatment” group? Would this crossover then affect the assessment of outcomes at 5 years? Would the reporting of these results also influence assessment of subjective outcomes, such as quality of life, because the participants will be aware of these results and are not blinded to treatment allocation? Back to top Article Information Corresponding Author: Ben Rees, MBBS, School of Surgery, Yorkshire and the Humber, Yorkshire, Doncaster Hospital, Doncaster DN2 5LT, England (ben.rees@nhs.net). Published Online: November 18, 2020. doi:10.1001/jamasurg.2020.5186 Conflict of Interest Disclosures: None reported. References 1. Cohen RV, Pereira TV, Aboud CM, et al. Effect of gastric bypass vs best medical treatment on early-stage chronic kidney disease in patients with type 2 diabetes and obesity: a randomized clinical trial.  JAMA Surg. Published online June 3, 2020. doi:10.1001/jamasurg.2020.0420PubMedGoogle Scholar http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png JAMA Surgery American Medical Association

The Role of Bariatric Surgery in Prevention of Kidney Disease Progression in Moderately Obese Patients With Type 2 Diabetes

JAMA Surgery , Volume 156 (2) – Feb 18, 2021

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Publisher
American Medical Association
Copyright
Copyright 2020 American Medical Association. All Rights Reserved.
ISSN
2168-6254
eISSN
2168-6262
DOI
10.1001/jamasurg.2020.5186
Publisher site
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Abstract

To the Editor We write regarding the article by Cohen et al, “Effect of Gastric Bypass vs Best Medical Treatment on Early-Stage Chronic Kidney Disease in Patients With Type 2 Diabetes and Obesity: A Randomized Clinical Trial.”1 This article was recently discussed at CRAMSURG, an online journal club based in the United Kingdom. We congratulate the authors for their efforts in performing this randomized clinical trial on a relevant and significant problem. We discussed a number of issues that we would like to raise. Although relevant clinical outcomes, such as blood pressure and glycemic control, and patient-centered outcomes, such as quality of life, have been assessed, it is not clear why microalbuminuria has been chosen as the primary outcome. Obesity and weight change have indirect effects on kidney function and microalbuminuria by their impact on diabetes and hypertension. The choice of microalbuminuria as a primary outcome is therefore not clear. This is particularly problematic given that this outcome is subject to misclassification (as acknowledged by the authors) and the randomization process does not address problems associated with the definition of the primary outcome. On this basis, a more appropriate primary outcome would have been a direct clinical outcome such as glycemic control. It appears that 21 of the patients did not meet eligibility criteria but were still included in the trial. Although this is noted in the supplementary documentation, it may not have been clear to all readers. Is it possible that this deviation may have introduced significant selection bias that has significant potential to affect the study results (and increase type I error)? The implications of interim analyses and reporting of outcomes may be significant. If the results are convincing, would the investigators now offer surgery (which appears clearly superior with regards to the primary and several other outcomes) to patients in the “best medical treatment” group? Would this crossover then affect the assessment of outcomes at 5 years? Would the reporting of these results also influence assessment of subjective outcomes, such as quality of life, because the participants will be aware of these results and are not blinded to treatment allocation? Back to top Article Information Corresponding Author: Ben Rees, MBBS, School of Surgery, Yorkshire and the Humber, Yorkshire, Doncaster Hospital, Doncaster DN2 5LT, England (ben.rees@nhs.net). Published Online: November 18, 2020. doi:10.1001/jamasurg.2020.5186 Conflict of Interest Disclosures: None reported. References 1. Cohen RV, Pereira TV, Aboud CM, et al. Effect of gastric bypass vs best medical treatment on early-stage chronic kidney disease in patients with type 2 diabetes and obesity: a randomized clinical trial.  JAMA Surg. Published online June 3, 2020. doi:10.1001/jamasurg.2020.0420PubMedGoogle Scholar

Journal

JAMA SurgeryAmerican Medical Association

Published: Feb 18, 2021

References