title: A pilot study evaluating predictors of postoperative outcomes after major abdominal surgery: Physiological capacity compared with the ASA physical status classification system.
abstract: BACKGROUND
  This pilot study compared the risk predictive value of preoperative physiological capacity (PC: defined by gas exchange measured during cardiopulmonary exercise testing) with the ASA physical status classification in the same patients (n=32) undergoing major abdominal cancer surgery.
  
  
  METHODS
  Uni- and multivariate logistic regression models were fitted to measurements of PC and ASA rank data determining their predictive value for postoperative morbidity. Receiver operating characteristic (ROC) curves were used to discriminate between the predictive abilities, exploring trade-offs between sensitivity and specificity.
  
  
  RESULTS
  Individual statistically significant predictors of postoperative morbidity included the ASA rank [P=0.038, area under the curve (AUC)=0.688, sensitivity=0.630, specificity=0.750] and three newly identified measures of PC: PAT (% predicted anaerobic threshold achieved, <75% vs > or =75%), DeltaHR1 (heart rate response from rest to the anaerobic threshold), and HR3 (heart rate at the anaerobic threshold). A two-variable model of PC measurements (DeltaHR1+PAT) was also shown to be statistically significant in the prediction of postoperative morbidity (P=0.023, AUC=0.826, sensitivity=0.813, specificity=0.688).
  
  
  CONCLUSIONS
  Three newly identified PC measures and the ASA rank were significantly associated with postoperative morbidity; none showed a statistically greater association compared with the others. PC appeared to improve predictive sensitivity. The potential for new unidentified measures of PC to predict postoperative outcomes remains unexplored.
authors.affiliation: Department of Anesthesiology and Perioperative Medicine, The University of Texas M.D. Anderson Cancer Center, Houston, USA. chightow@mdanderson.org
authors.forename: C E
authors.initials: CE
authors.lastname: Hightower
authors.forename: B J
authors.initials: BJ
authors.lastname: Riedel
authors.forename: B W
authors.initials: BW
authors.lastname: Feig
authors.forename: G S
authors.initials: GS
authors.lastname: Morris
authors.forename: J E
authors.initials: JE
authors.lastname: Ensor
authors.forename: V D
authors.initials: VD
authors.lastname: Woodruff
authors.forename: M D
authors.initials: MD
authors.lastname: Daley-Norman
authors.forename: X G
authors.initials: XG
authors.lastname: Sun
mesh_terms: D000008:Abdominal Neoplasms / Q000503:physiopathology / Q000601:surgery*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004812:Epidemiologic Methods; D005080:Exercise Test / Q000379:methods; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D011300:Preoperative Care / Q000379:methods; D011379:Prognosis; D011659:Pulmonary Gas Exchange / Q000502:physiology; D016896:Treatment Outcome; D055815:Young Adult