title: The effect of obesity on acute kidney injury after cardiac surgery.
abstract: OBJECTIVE
  Postoperative acute kidney injury is a frequent and serious consequence of cardiac surgery. We undertook to investigate the association of obesity and the risk of acute kidney injury development after cardiac surgery.
  
  
  METHODS
  A total of 432 patients who underwent cardiac surgery with cardiopulmonary bypass between October 2009 and August 2010 were included in the final retrospective analysis. Obesity was defined as body mass index 30 kg/m(2) or greater. Acute kidney injury was defined as a creatinine increase of 25% or more from baseline at 48 hours after surgery.
  
  
  RESULTS
  The overall incidence of acute kidney injury was 29.9% (n = 129). There was an increased incidence of postoperative renal impairment in the obese versus nonobese cohort; however, this was not statistically significant (39% vs 25.9%, P = .007). Multivariate logistic regression revealed that body mass index 30 kg/m(2) or greater was independently associated with the development of postoperative acute kidney injury (odds ratio [OR], 2.12; 95% confidence interval [CI], 1.27-3.54; P = .004), as were age (OR, 0.98; 95% CI, 0.96-1.0; P = .04) and cardiopulmonary bypass time (OR, 0.99; 95% CI, 0.98-1.0; P = .048).
  
  
  CONCLUSIONS
  Obesity with body mass index 30 kg/m(2) or greater is independently associated with an increased risk of acute kidney injury after cardiac surgery. Further understanding of the molecular basis of this association is critical to the design of preventative strategies.
authors.affiliation: Department of Cardiothoracic Surgery, Mater Private Hospital, Dublin, Ireland. Electronic address: kaosulli@tcd.ie.
authors.forename: Katie E
authors.initials: KE
authors.lastname: O'Sullivan
authors.affiliation: Division of Vascular Surgery, Toronto General Hospital, University of Toronto, Canada.
authors.forename: John S
authors.initials: JS
authors.lastname: Byrne
authors.affiliation: Department of Nephrology, Mater Private Hospital, Dublin, Ireland.
authors.forename: Amy
authors.initials: A
authors.lastname: Hudson
authors.affiliation: Department of Cardiothoracic Surgery, Mater Private Hospital, Dublin, Ireland.
authors.forename: Anna Marie
authors.initials: AM
authors.lastname: Murphy
authors.affiliation: Department of Nephrology, Mater Private Hospital, Dublin, Ireland.
authors.forename: Denise M
authors.initials: DM
authors.lastname: Sadlier
authors.affiliation: Department of Cardiothoracic Surgery, Mater Private Hospital, Dublin, Ireland.
authors.forename: John P
authors.initials: JP
authors.lastname: Hurley
mesh_terms: D058186:Acute Kidney Injury / Q000209:etiology*; D000368:Aged; D015992:Body Mass Index; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D002315:Cardiopulmonary Bypass; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications*; D012189:Retrospective Studies; D012307:Risk Factors
keywords: acute kidney injury; cardiac surgery; obesity; postoperative