title: Outcomes of off-pump versus on-pump coronary artery bypass grafting: Impact of preoperative risk.
abstract: BACKGROUND
  It is unknown whether purported benefits of off-pump coronary artery bypass grafting are patient-specific within the Society of Thoracic Surgeons National Cardiac Database or dependent on center volume or operating surgeon.
  
  
  METHODS
  The Society of Thoracic Surgeons National Cardiac Database was queried for all patients undergoing nonemergency, isolated coronary artery bypass between January 1, 2005, and December 31, 2010, who had Predicted Risk of Mortality scores and participant/surgeon identifiers. Of these 876,081 patients ("all sites"), 210,469 underwent surgery at participant sites that had performed more than 300 off-pump and 300 on-pump coronary artery bypass operations during the 6-year study period ("high-volume sites"). Operative mortality, stroke, acute renal failure, mortality or morbidity, and prolonged postoperative length of stay were analyzed with conditional logistic models for all sites and for high-volume sites, stratified by participant center and surgeon, and adjusted for 30 variables that comprise the Society of Thoracic Surgeons coronary artery bypass grafting risk models.
  
  
  RESULTS
  Off-pump coronary artery bypass was associated with a significant reduction in risk of death, stroke, acute renal failure, mortality or morbidity, and postoperative length of stay compared with on-pump coronary artery bypass after adjustment for 30 patient risk factors in the overall sample. This held true within high-volume centers. In the overall sample, there was a significant (P < .05) interaction between off-pump coronary artery bypass and Predicted Risk of Mortality for death, stroke, acute renal failure, and mortality or morbidity.
  
  
  CONCLUSIONS
  Off-pump coronary artery bypass was associated with reduced adverse events compared with on-pump coronary artery bypass after adjustment for 30 patient risk factors and center and surgeon identity. Patients with higher Predicted Risk of Mortality scores had the largest apparent benefit.
authors.affiliation: Division of Cardiothoracic Surgery, Emory University School of Medicine, Atlanta, GA 30308, USA.
authors.forename: Marek
authors.initials: M
authors.lastname: Polomsky
authors.forename: Xia
authors.initials: X
authors.lastname: He
authors.forename: Sean M
authors.initials: SM
authors.lastname: O'Brien
authors.forename: John D
authors.initials: JD
authors.lastname: Puskas
mesh_terms: D058186:Acute Kidney Injury / Q000209:etiology; D000368:Aged; D002315:Cardiopulmonary Bypass / Q000009:adverse effects / Q000401:mortality; D016009:Chi-Square Distribution; D001026:Coronary Artery Bypass / Q000009:adverse effects / Q000379:methods* / Q000401:mortality; D047549:Coronary Artery Bypass, Off-Pump / Q000009:adverse effects / Q000401:mortality; D005260:Female; D017052:Hospital Mortality; D061847:Hospitals, High-Volume; D061846:Hospitals, Low-Volume; D006801:Humans; D007902:Length of Stay; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D018579:Patient Selection; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D020521:Stroke / Q000209:etiology; D013997:Time Factors; D016896:Treatment Outcome; D014481:United States