title: Postoperative blood urea nitrogen is associated with stroke in cardiac surgical patients.
abstract: BACKGROUND
  This case-control study identified perioperative risk factors associated with postoperative stroke risk after all cardiac surgical procedures.
  
  
  METHODS
  Among 5498 adults 18 to 90 years old who underwent cardiac surgical procedures from 2005 to 2010, we identified 180 patients who suffered a stroke within 10 days postoperatively. Controls were randomly selected and frequency matched for sex and age-band to cases. Univariate and multivariate logistic regression analyses were performed to ascertain risk factors for postoperative stroke.
  
  
  RESULTS
  Emergency surgical procedures (odds ratio [OR], 3.04; 95% confidence interval [CI], 1.80 to 5.10), current smoking (OR, 1.97; 95% CI, 1.29 to 3.00), peripheral vascular disease (OR, 2.80; 95% CI, 1.41 to 5.53), and previous stroke with residual paralysis (OR, 4.27; 95% CI ,1.18 to 15.38) were associated with increased stroke risk. Preoperative blood pressures were higher in patients with cases than in controls (p < 0.0001). Log of immediate postoperative blood urea nitrogen (BUN) was higher in patients with cases than in controls (p < 0.0001). In adjusted multivariable logistic regression, postoperative BUN was associated with increased odds of stroke (OR, 2.37 per 25% increase in BUN, p < 0.0001). Postoperative stroke risk was also predicted by emergency surgical procedures (OR, 2.70, p = 0.014), current smoking (OR, 2.82, p = 0.002), and preoperative diastolic blood pressure (DBP) (OR, 1.77 for every 10-point increase in DBP, p < 0.0001). Receiver operator characteristic curves indicated that postoperative BUN (area under the curve, 0.855) largely explained the increased postoperative stroke risk.
  
  
  CONCLUSIONS
  In these analyses, we identified BUN as a marker of heightened postoperative stroke risk after cardiac surgical procedures. Postoperative risk markers may improve assessment of delayed postoperative strokes.
authors: Department of Neurology, Wake Forest University Health Sciences, Winston-Salem, North Carolina. Electronic address: marnan@wakehealth.edu.
authors: Martinson K
authors: MK
authors: Arnan
authors: Department of Anesthesia, Division of Cardiac Anesthesia, Mills-Peninsula Medical Center, Burlingame, California.
authors: Tyken C
authors: TC
authors: Hsieh
authors: Department of Cardiology, Wake Forest University Health Sciences, Winston-Salem, North Carolina.
authors: Joseph
authors: J
authors: Yeboah
authors: Division of Public Health Sciences, Wake Forest University Health Sciences, Winston-Salem, North Carolina.
authors: Alain G
authors: AG
authors: Bertoni
authors: Division of Public Health Sciences, Wake Forest University Health Sciences, Winston-Salem, North Carolina.
authors: Gregory L
authors: GL
authors: Burke
authors: Department of Neurology, Johns Hopkins University, Baltimore, Maryland.
authors: Zainab
authors: Z
authors: Bahrainwala
authors: Department of Neurology, Johns Hopkins University, Baltimore, Maryland.
authors: Maura A
authors: MA
authors: Grega
authors: Division of Cardiac Surgery, Johns Hopkins University, Baltimore, Maryland.
authors: William A
authors: WA
authors: Baumgartner
authors: Department of Neurology, Johns Hopkins University, Baltimore, Maryland.
authors: Rebecca F
authors: RF
authors: Gottesman
mesh_terms: D000046:Academic Medical Centers; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000704:Analysis of Variance; D015142:Baltimore; D015415:Biomarkers / Q000097:blood; D001806:Blood Urea Nitrogen; D006348:Cardiac Surgical Procedures / Q000009:adverse effects* / Q000379:methods / Q000401:mortality*; D016022:Case-Control Studies; D002423:Cause of Death; D016208:Databases, Factual; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011183:Postoperative Complications / Q000175:diagnosis / Q000401:mortality; D012189:Retrospective Studies; D012737:Sex Factors; D020521:Stroke / Q000097:blood* / Q000209:etiology / Q000401:mortality*; D016019:Survival Analysis; D055815:Young Adult
chemical_list: D015415:Biomarkers