title: The impact of acute kidney injury on midterm outcomes after coronary artery bypass graft surgery: a matched propensity score analysis.
abstract: BACKGROUND
  The development of acute kidney injury (AKI) after coronary artery bypass graft (CABG) surgery is associated with increased short- and long-term mortality. Whether AKI has a causal relationship with subsequent mortality or whether the development of AKI simply occurs in patients with more comorbidity undergoing more complex procedures remains unresolved.
  
  
  RESULTS
  This was an observational cohort study of prospectively collected data from 4694 patients discharged from the hospital after first-time CABG surgery at a tertiary cardiac center between 2003 and 2008. AKI was defined using the Risk, Injury, Failure, Loss, and End stage (RIFLE) criteria, which require at least a 50% increase in serum creatinine. The primary outcome measure was all-cause mortality determined via UK Office of National Statistics. A total of 562 (12.0%) of patients developed AKI after CABG surgery. Patients who developed AKI were older, more likely to be female, and had more comorbidity than patients who did not develop AKI. In a Cox multivariable analysis, the development of AKI was an independent predictor of midterm mortality (hazard ratio, 1.80; 95% confidence interval, 1.50-2.16). Subsequently, a comparison of 562 patients who sustained AKI with 562 propensity score-matched patients who did not sustain AKI was undertaken. After propensity matching, baseline clinical and operative characteristics were similar between both groups. After Cox multivariable analysis of the propensity-matched cohort, AKI remained an independent predictor of midterm mortality (hazard ratio, 1.52; 95% confidence interval, 1.19-1.93).
  
  
  CONCLUSIONS
  The development of AKI after CABG is a serious event associated with worse midterm survival. This excess mortality cannot be explained simply by coexisting comorbidity and surgical complexity.
authors.affiliation: Renal and Cardiac Directorate, Barts and the London National Health Service Trust, London, England; William Harvey Research Institute, Queen Mary and Westfield University, London, England; National Institute for Health Research Cardiovascular Biomedical Research Unit, London Chest Hospital, London, England.
authors.forename: Sean
authors.initials: S
authors.lastname: Gallagher
authors.affiliation: Renal and Cardiac Directorate, Barts and the London National Health Service Trust, London, England; William Harvey Research Institute, Queen Mary and Westfield University, London, England; National Institute for Health Research Cardiovascular Biomedical Research Unit, London Chest Hospital, London, England.
authors.forename: Dan A
authors.initials: DA
authors.lastname: Jones
authors.affiliation: Renal and Cardiac Directorate, Barts and the London National Health Service Trust, London, England; National Institute for Health Research Cardiovascular Biomedical Research Unit, London Chest Hospital, London, England.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Lovell
authors.affiliation: Renal and Cardiac Directorate, Barts and the London National Health Service Trust, London, England.
authors.forename: Sevda
authors.initials: S
authors.lastname: Hassan
authors.affiliation: Renal and Cardiac Directorate, Barts and the London National Health Service Trust, London, England; National Institute for Health Research Cardiovascular Biomedical Research Unit, London Chest Hospital, London, England.
authors.forename: Andrew
authors.initials: A
authors.lastname: Wragg
authors.affiliation: Renal and Cardiac Directorate, Barts and the London National Health Service Trust, London, England; William Harvey Research Institute, Queen Mary and Westfield University, London, England; National Institute for Health Research Cardiovascular Biomedical Research Unit, London Chest Hospital, London, England.
authors.forename: Akhil
authors.initials: A
authors.lastname: Kapur
authors.affiliation: Renal and Cardiac Directorate, Barts and the London National Health Service Trust, London, England; William Harvey Research Institute, Queen Mary and Westfield University, London, England; National Institute for Health Research Cardiovascular Biomedical Research Unit, London Chest Hospital, London, England.
authors.forename: Rakesh
authors.initials: R
authors.lastname: Uppal
authors.affiliation: Renal and Cardiac Directorate, Barts and the London National Health Service Trust, London, England; William Harvey Research Institute, Queen Mary and Westfield University, London, England; National Institute for Health Research Cardiovascular Biomedical Research Unit, London Chest Hospital, London, England. Electronic address: m.m.yaqoob@qmul.ac.uk.
authors.forename: Muhammad M
authors.initials: MM
authors.lastname: Yaqoob
mesh_terms: D058186:Acute Kidney Injury / Q000175:diagnosis / Q000453:epidemiology* / Q000401:mortality; D000367:Age Factors; D000368:Aged; D016009:Chi-Square Distribution; D015897:Comorbidity; D001026:Coronary Artery Bypass / Q000009:adverse effects* / Q000401:mortality; D003324:Coronary Artery Disease / Q000401:mortality / Q000601:surgery*; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008131:London / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010351:Patient Discharge; D057216:Propensity Score; D016016:Proportional Hazards Models; D012307:Risk Factors; D012737:Sex Factors; D062606:Tertiary Care Centers; D013997:Time Factors; D016896:Treatment Outcome