title: Comparison of the utility of preoperative versus postoperative B-type natriuretic peptide for predicting hospital length of stay and mortality after primary coronary artery bypass grafting.
abstract: BACKGROUND
  Preoperative B-type natriuretic peptide (BNP) is known to predict adverse outcomes after cardiac surgery. The value of postoperative BNP for predicting adverse outcomes is less well delineated. The authors hypothesized that peak postoperative plasma BNP (measured postoperative days 1-5) predicts hospital length of stay (HLOS) and mortality in patients undergoing primary coronary artery bypass grafting, even after adjusting for preoperative BNP and perioperative clinical risk factors.
  
  
  METHODS
  This study is a prospective longitudinal study of 1,183 patients undergoing primary coronary artery bypass grafting surgery. Mortality was defined as all-cause death within 5 yr after surgery. Cox proportional hazards analyses were conducted to separately evaluate the associations between peak postoperative BNP and HLOS and mortality. Multivariable adjustments were made for patient demographics, preoperative BNP concentration, and clinical risk factors. BNP measurements were log10 transformed before analysis.
  
  
  RESULTS
  One hundred fifteen deaths (9.7%) occurred in the cohort (mean follow-up = 4.3 yr, range = 2.38-5.0 yr). After multivariable adjustment for preoperative BNP and clinical covariates, peak postoperative BNP predicted HLOS (hazard ratio [HR] = 1.28, 95% CI = 1.002-1.64, P = 0.049) but not mortality (HR = 1.62, CI = 0.71-3.68, P = 0.25), whereas preoperative BNP independently predicted HLOS (HR = 1.09, CI = 1.01-1.18, P = 0.03) and approached being an independent predictor of mortality (HR = 1.36, CI = 0.96-1.94, P = 0.08). When preoperative and peak postoperative BNP were separately adjusted for within the clinical multivariable models, each independently predicted HLOS (preoperative BNP HR = 1.13, CI = 1.05-1.21, P = 0.0007; peak postoperative BNP HR = 1.44, CI = 1.15-1.81, P = 0.001) and mortality (preoperative BNP HR = 1.50, CI = 1.09-2.07, P = 0.01; peak postoperative BNP HR = 2.29, CI = 1.11-4.73, P = 0.02).
  
  
  CONCLUSIONS
  Preoperative BNP may be better than peak postoperative BNP for predicting HLOS and longer term mortality after primary coronary artery bypass grafting surgery.
authors.affiliation: Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA. afox@partners.org
authors.forename: Amanda A
authors.initials: AA
authors.lastname: Fox
authors.forename: Jochen D
authors.initials: JD
authors.lastname: Muehlschlegel
authors.forename: Simon C
authors.initials: SC
authors.lastname: Body
authors.forename: Stanton K
authors.initials: SK
authors.lastname: Shernan
authors.forename: Kuang-Yu
authors.initials: KY
authors.lastname: Liu
authors.forename: Tjorvi E
authors.initials: TE
authors.lastname: Perry
authors.forename: Sary F
authors.initials: SF
authors.lastname: Aranki
authors.forename: E Francis
authors.initials: EF
authors.lastname: Cook
authors.forename: Edward R
authors.initials: ER
authors.lastname: Marcantonio
authors.forename: Charles D
authors.initials: CD
authors.lastname: Collard
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001026:Coronary Artery Bypass / Q000401:mortality* / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007902:Length of Stay / Q000706:statistics & numerical data*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D011183:Postoperative Complications / Q000401:mortality; D011184:Postoperative Period; D011237:Predictive Value of Tests; D057234:Preoperative Period; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012307:Risk Factors; D012959:Socioeconomic Factors; D016019:Survival Analysis; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D020097:Natriuretic Peptide, Brain