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Long-term effects of bariatric surgery on acute kidney injury: a propensity-matched cohort in the UK Clinical Practice Research Datalink
  1. Uwe Koppe1,2,
  2. Dorothea Nitsch1,3,
  3. Kathryn E Mansfield1,
  4. Rohini Mathur1,
  5. Krishnan Bhaskaran1,
  6. Rachel L Batterham4,5,6,
  7. Liam Smeeth1,
  8. Ian J Douglas1
  1. 1 Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK
  2. 2 Department of Infectious Disease Epidemiology, Robert Koch Institute, Berlin, Germany
  3. 3 Royal Free London NHS Trust, London, UK
  4. 4 Centre for Obesity Research, Rayne Institute, Department of Medicine, University College London, London, UK
  5. 5 University College London Hospital Bariatric Centre for Weight Management and Metabolic Surgery, London, UK
  6. 6 National Institute of Health Research, University College London Hospital Biomedical Research Centre, London, UK
  1. Correspondence to Dr Uwe Koppe; koppeu{at}


Objective Bariatric surgery is an effective method of weight reduction and has been associated with acute kidney injury (AKI) as a perioperative event. However, the long-term effects of the weight reduction after surgery on AKI are unknown. The objective of this study is to quantify the association of bariatric surgery with later risk of AKI.

Design This study uses a propensity score-matched cohort of patients from the UK Clinical Practice Research Datalink database with and without bariatric surgery to compare rates of AKI episodes derived from linkage to the Hospital Episode Statistics.

Setting England, UK.

Participants We included 2643 patients with bariatric surgery and 2595 patients without.

Results Results were compatible with an increased risk of AKI in the first 30 days following surgery compared with patients without surgery, but AKI incidence was substantially decreased in patients with bariatric surgery during long-term follow-up (rate ratio 0.37, 95% CI 0.23 to 0.61) even after accounting for chronic kidney disease status at baseline. Over the whole period of follow-up, bariatric surgery had a net protective effect on risk of AKI (rate ratio 0.45, 95% CI 0.28 to 0.72).

Conclusions Bariatric surgery was associated with protective effects on AKI incidence during long-term follow-up. While the risk of AKI may be increased within the first 30 days, the net effect seen was beneficial.

  • clinical practice research datalink
  • acute kidney injury
  • obesity
  • bariatric surgery

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  • Contributors UK, DN, RLB, IJD and LS were responsible for conceptualisation of the study and formulate the research goals and aims. UK, DN, KEM, RM, KB, RLB, LS and IJD developed the methodology and models. UK, KEM, KB, IJD and RM worked on the data curation. UK performed the statistical analysis and wrote the original draft. UK, DN, KEM, RM, KB, RLB, LS and IJD reviewed and commented the draft and gave input on editing.

  • Funding RM is supported by a Sir Henry Wellcome Postdoctoral Fellowship from the Wellcome Trust (201375/Z/16/Z). KB holds a Sir Henry Dale fellowship jointly funded by the Wellcome Trust and the Royal Society (107731/Z/15/Z). RLB is an NIHR Research Professor and supported by funding from the Rosetrees Trust and the Sir Jules Thorn Charitable Trust. LS is supported by a senior clinical fellowship from the Wellcome Trust (098504/Z/12/Z). IJD is funded by an unrestricted grant from GlaxoSmithKline.

  • Disclaimer None of the funders had any involvement in the design of the study, the data collection and analysis, the writing of the report or the decision to submit the paper for publication.

  • Competing interests None declared.

  • Patient consent Not required.

  • Ethics approval This study was approved by the London School of Hygiene & Tropical Medicine Ethics Committee (LSHTM MSc Ethics Ref: 11065) and the Independent Scientific Advisory Committee on Medicines and Healthcare Products Regulatory Agency database research (approval number: 16_106R).

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement The data were obtained from the Clinical Practice Research Datalink (CPRD). CPRD data governance does not allow us to distribute patient data to other parties. Researchers may apply for data access at The codes used to produce the data for this study are provided in the supporting information.

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