title: Performance of the European System for Cardiac Operative Risk Evaluation II: a meta-analysis of 22 studies involving 145,592 cardiac surgery procedures.
abstract: OBJECTIVE
  A systematic review of the European System for Cardiac Operative Risk Evaluation (euroSCORE) II performance for prediction of operative mortality after cardiac surgery has not been performed. We conducted a meta-analysis of studies based on the predictive accuracy of the euroSCORE II.
  
  
  METHODS
  We searched the Embase and PubMed databases for all English-only articles reporting performance characteristics of the euroSCORE II. The area under the receiver operating characteristic curve, the observed/expected mortality ratio, and observed-expected mortality difference with their 95% confidence intervals were analyzed.
  
  
  RESULTS
  Twenty-two articles were selected, including 145,592 procedures. Operative mortality occurred in 4293 (2.95%), whereas the expected events according to euroSCORE II were 4802 (3.30%). Meta-analysis of these studies provided an area under the receiver operating characteristic curve of 0.792 (95% confidence interval, 0.773-0.811), an estimated observed/expected ratio of 1.019 (95% confidence interval, 0.899-1.139), and observed-expected difference of 0.125 (95% confidence interval, -0.269 to 0.519). Statistical heterogeneity was detected among retrospective studies including less recent procedures. Subgroups analysis confirmed the robustness of combined estimates for isolated valve procedures and those combined with revascularization surgery. A significant overestimation of the euroSCORE II with an observed/expected ratio of 0.829 (95% confidence interval, 0.677-0.982) was observed in isolated coronary artery bypass grafting and a slight underestimation of predictions in high-risk patients (observed/expected ratio 1.253 and observed-expected difference 1.859).
  
  
  CONCLUSIONS
  Despite the heterogeneity, the results from this meta-analysis show a good overall performance of the euroSCORE II in terms of discrimination and accuracy of model predictions for operative mortality. Validation of the euroSCORE II in prospective populations needs to be further studied for a continuous improvement of patients' risk stratification before cardiac surgery.
authors.affiliation: Division of Cardiac Surgery, Department of Emergency and Organ Transplant, University of Bari Aldo Moro, Bari, Italy.
authors.forename: Pietro
authors.initials: P
authors.lastname: Guida
authors.affiliation: Division of Cardiac Surgery, Department of Emergency and Organ Transplant, University of Bari Aldo Moro, Bari, Italy.
authors.forename: Florinda
authors.initials: F
authors.lastname: Mastro
authors.affiliation: Division of Cardiac Surgery, Department of Emergency and Organ Transplant, University of Bari Aldo Moro, Bari, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Scrascia
authors.affiliation: Department of Surgery, McMaster University, Hamilton, Canada; Population Health Research Institute, McMaster University and Hamilton Health Sciences, Hamilton, Canada.
authors.forename: Richard
authors.initials: R
authors.lastname: Whitlock
authors.affiliation: Division of Cardiac Surgery, Department of Emergency and Organ Transplant, University of Bari Aldo Moro, Bari, Italy. Electronic address: domenico.paparella@uniba.it.
authors.forename: Domenico
authors.initials: D
authors.lastname: Paparella
mesh_terms: D019540:Area Under Curve; D006348:Cardiac Surgical Procedures / Q000009:adverse effects / Q000401:mortality*; D003661:Decision Support Techniques; D017052:Hospital Mortality; D006801:Humans; D011237:Predictive Value of Tests; D012372:ROC Curve; D018570:Risk Assessment; D012307:Risk Factors; D016896:Treatment Outcome