title: Acute kidney injury is associated with increased long-term mortality after cardiothoracic surgery.
abstract: BACKGROUND
  Long-term survival after acute kidney injury (AKI) is poorly studied. We report the relationship between long-term mortality and AKI with small changes in serum creatinine during hospitalization after various cardiothoracic surgery procedures.
  
  
  RESULTS
  This was a retrospective study of 2973 patients with no history of chronic kidney disease who were discharged from the hospital after cardiothoracic surgery between 1992 and 2002. AKI was defined by the RIFLE classification (Risk, Injury, Failure, Loss, and End stage), which requires at least a 50% increase in serum creatinine and stratifies patients into 3 grades of AKI: Risk, injury, and failure. Patient survival was determined through the National Social Security Death Index. Long-term survival was analyzed with a risk-adjusted Cox proportional hazards regression model. Survival was worse among patients with AKI and was proportional to its severity, with an adjusted hazard ratio of 1.23 (95% CI 1.06 to 1.42) for the least severe RIFLE risk class and 2.14 (95% CI 1.73 to 2.66) for the RIFLE failure class compared with patients without AKI. Survival was worse among all subgroups of cardiothoracic surgery with AKI except for valve surgery. Patients with complete renal recovery after AKI still had an increased adjusted hazard ratio for death of 1.28 (95% CI 1.11 to 1.48) compared with patients without AKI.
  
  
  CONCLUSIONS
  The risk of death associated with AKI after cardiothoracic surgery remains high for 10 years regardless of other risk factors, even for those patients with complete renal recovery. Improved renal protection and closer postdischarge follow-up of renal function may be warranted.
authors.affiliation: Department of Medicine, Division of Thoracic and Cardiovascular Surgery, University of Florida College of Medicine, Gainesville, Fla 32610-0286, USA.
authors.forename: Charles E
authors.initials: CE
authors.lastname: Hobson
authors.forename: Sinan
authors.initials: S
authors.lastname: Yavas
authors.forename: Mark S
authors.initials: MS
authors.lastname: Segal
authors.forename: Jesse D
authors.initials: JD
authors.lastname: Schold
authors.forename: Curtis G
authors.initials: CG
authors.lastname: Tribble
authors.forename: A Joseph
authors.initials: AJ
authors.lastname: Layon
authors.forename: Azra
authors.initials: A
authors.lastname: Bihorac
mesh_terms: D058186:Acute Kidney Injury / Q000401:mortality* / Q000628:therapy; D000368:Aged; D006348:Cardiac Surgical Procedures / Q000401:mortality*; D002423:Cause of Death; D015897:Comorbidity; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000401:mortality*; D016016:Proportional Hazards Models; D020127:Recovery of Function; D006435:Renal Dialysis / Q000706:statistics & numerical data; D012189:Retrospective Studies; D012307:Risk Factors