title: Occult renal dysfunction: a mortality and morbidity risk factor in coronary artery bypass grafting surgery.
abstract: OBJECTIVE
  Elevated preoperative serum creatinine is considered an independent risk factor for postoperative mortality and morbidity in patients undergoing coronary artery bypass grafting. However, the impact of occult renal dysfunction, defined as an impairment of glomerular filtration rate with normal serum creatinine, is still unknown. The aim of this study was to analyze the effects of occult renal dysfunction on early outcomes after coronary artery bypass grafting.
  
  
  METHODS
  This was a retrospective, observational, cohort study of prospectively collected data on 9159 consecutive patients with normal serum creatinine levels undergoing coronary artery bypass grafting between April 1996 and February 2009. Patients were divided into two groups based on preoperative creatinine clearance estimated with the Cockcroft-Gault equation: 5484 patients with a creatinine clearance ≥ 60 mL/min and 3675 patients with a creatinine clearance < 60 mL/min (occult renal dysfunction group).
  
  
  RESULTS
  Overall in-hospital mortality was 1%. Occult renal dysfunction was associated with a doubling in the risk of operative mortality (1.4% vs 0.7%; P = .001), postoperative renal dysfunction (5.1% vs 2.5%; P < .0001), and need for dialysis (0.8% vs 0.4%; P = .014). Moreover, occult renal dysfunction increased the risk of stroke (1% vs 0.3%; P < .0001), arrhythmia (28.5% vs 21.2%; P < .0001), and hospital stay > 7 days (36.45 vs 24.5%; P < .0001). In a multivariable analysis adjusting for preoperative risk factors, occult renal dysfunction was confirmed to be an independent predictor of mortality (odds ratio, 1.72), postoperative renal dysfunction (odds ratio, 1.9), dialysis (odds ratio, 1.82), stroke (odds ratio, 2.6) arrhythmia (odds ratio, 1.42), and hospital stay > 7 days (odds ratio, 1.65).
  
  
  CONCLUSIONS
  Occult renal dysfunction is an independent risk factor for early mortality and morbidity in patients undergoing coronary artery bypass grafting.
authors.affiliation: Bristol Heart Institute, University of Bristol, Bristol, United Kingdom.
authors.forename: Antonio
authors.initials: A
authors.lastname: Miceli
authors.forename: Vito D
authors.initials: VD
authors.lastname: Bruno
authors.forename: Radek
authors.initials: R
authors.lastname: Capoun
authors.forename: Francesco
authors.initials: F
authors.lastname: Romeo
authors.forename: Gianni D
authors.initials: GD
authors.lastname: Angelini
authors.forename: Massimo
authors.initials: M
authors.lastname: Caputo
mesh_terms: D000368:Aged; D001145:Arrhythmias, Cardiac / Q000209:etiology; D015415:Biomarkers / Q000097:blood; D016009:Chi-Square Distribution; D001026:Coronary Artery Bypass / Q000009:adverse effects* / Q000401:mortality; D003324:Coronary Artery Disease / Q000150:complications / Q000401:mortality / Q000601:surgery*; D003404:Creatinine / Q000097:blood; D004739:England; D005260:Female; D005919:Glomerular Filtration Rate; D017052:Hospital Mortality; D006801:Humans; D007668:Kidney / Q000503:physiopathology*; D007674:Kidney Diseases / Q000150:complications* / Q000401:mortality / Q000503:physiopathology / Q000628:therapy; D007902:Length of Stay; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D057216:Propensity Score; D006435:Renal Dialysis; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D020521:Stroke / Q000209:etiology; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; D003404:Creatinine