title: Prediction of bleeding after cardiac surgery: comparison of model performances: a prospective observational study.
abstract: OBJECTIVE
  Primary aims were to (1) perform external validation of the Papworth Bleeding Risk Score, and (2) compare the usefulness of the Dyke et al universal definition of perioperative bleeding with that used in the Papworth Bleeding Risk Score. A secondary aim was to use a locally developed logistic prediction model for severe postoperative bleeding to investigate whether prediction could be improved with inclusion of the variable "surgeon" or selected intraoperative variables.
  
  
  METHODS
  Single-center prospective observational study.
  
  
  METHODS
  University hospital.
  
  
  METHODS
  7,030 adults undergoing cardiac surgery.
  
  
  METHODS
  None.
  
  
  RESULTS
  Papworth Bleeding Risk Score could identify the group of patients with low risk of postoperative bleeding, with negative predictive value of 0.98, when applying the Papworth Score on this population. The positive predictive value was low; only 15% of the patients who were rated high risk actually suffered from increased postoperative bleeding when using the Papworth Score on this population. Using the universal definition of perioperative bleeding proposed by Dyke et al, 28% of patients in the Papworth high-risk group exceeded the threshold of excessive bleeding in this population. The local models showed low ability for discrimination (area under the receiver operating characteristics curve<0.75). Addition of the factor "surgeon" or selected intraoperative variables did not substantially improve the models.
  
  
  CONCLUSIONS
  Prediction of risk for excessive bleeding after cardiac surgery was not possible using clinical variables only, independent of endpoint definition and inclusion of the variable "surgeon" or of selected intraoperative variables. These findings may be due to incomplete understanding of the causative factors underlying excessive bleeding.
authors.affiliation: Departments of *Circulation and Medical Imaging; Department of Cardiothoracic Anaesthesia and Intensive Care. Electronic address: guri.greiff@gmail.com.
authors.forename: Guri
authors.initials: G
authors.lastname: Greiff
authors.affiliation: Departments of *Circulation and Medical Imaging; Clinic of Anaesthesia and Intensive Care.
authors.forename: Hilde
authors.initials: H
authors.lastname: Pleym
authors.affiliation: Departments of *Circulation and Medical Imaging; Department of Cardiothoracic Anaesthesia and Intensive Care.
authors.forename: Roar
authors.initials: R
authors.lastname: Stenseth
authors.affiliation: Laboratory Medicine, Children's and Women's Health, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Kristin S
authors.initials: KS
authors.lastname: Berg
authors.affiliation: Departments of *Circulation and Medical Imaging; Department of Immunology and Transfusion Medicine, St. Olav University Hospital, Trondheim, Norway.
authors.forename: Alexander
authors.initials: A
authors.lastname: Wahba
authors.affiliation: Laboratory Medicine, Children's and Women's Health, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway; Department of Cardiothoracic Surgery.
authors.forename: Vibeke
authors.initials: V
authors.lastname: Videm
mesh_terms: D000368:Aged; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D008962:Models, Theoretical; D019106:Postoperative Hemorrhage / Q000175:diagnosis* / Q000209:etiology*; D011446:Prospective Studies; D012372:ROC Curve; D015203:Reproducibility of Results; D012307:Risk Factors
keywords: bleeding endpoint; cardiac surgery; hemorrhage; risk prediction; risk score